Nazaretski200904 200904 Physical Review
B 79, 132401, 2009, Detection of localized ferromagnetic resonance in a
continuous thin film via magnetic resonance force microscopy, We present
magnetic resonance force microscopy MRFM measurements of ferromagnetic
resonance in a 50 nm thick permalloy film tilted with respect to the
direction of the external magnetic field. At small probe-sample distances
the MRFM spectrum breaks up into multiple modes, which we identify as
local ferromagnetic resonances confined by the magnetic field of the MRFM
tip. Micromagnetic simulations support this identification of the modes
and show they are stabilized in the region where the dipolar tip field has
a component antiparallel to the applied field.
Hammel ferromagnetic thin
film SQUID
Rugar200902 200902 Nanoscale magnetic
resonance imaging, We have combined ultrasensitive magnetic resonance
force mi- croscopy (MRFM) with 3D image reconstruction to achieve magnetic
resonance imaging (MRI) with resolution 10 nm. The image reconstruction
converts measured magnetic force data into a 3D map of nuclear spin
density, taking advantage of the unique characteristics of the ``resonant
slice'' that is projected outward from a nanoscale magnetic tip. The basic
principles are demon- strated by imaging the 1H spin density within
individual tobacco mosaic virus particles sitting on a nanometer-thick
layer of ad- sorbed hydrocarbons. This result, which represents a 100
million- fold improvement in volume resolution over conventional MRI,
demonstrates the potential of MRFM as a tool for 3D, elementally selective
imaging on the nanometer scale. rugar
3D imaging milestone
Sidles200902 200902 Proceedings of the
National Academy of Science, vol 106, no 8, February 24, 2009, Spin
microscopy's heritage, achievements, and prospects, Achieving
3-dimensional, in-depth, atomic-resolution biological microscopy of
undenatured specimens is one of the oldest dreams of science, and for good
reason: it unites the thrilling prospect of opening vast new scientific f
rontiers with cutting-edge technical challenges from every domain of
?mathematics, science, and engineering. Sidles
history future references
Rugar
Malcomb200812 200812 University of
Washington Press (thesis), Active Compensation of Coherent Parasitic
Excitation in Magnetic Resonance Force Microscopy, Active compensation can
mitigate the effects of the primary parasitic signal in magnetic resonance
force microscopy, resulting in an increase in both precision and accuracy
of force measurements. Sidles
control cantilever
dynamics
Jacky200812 200812 Review of
Scientific Instruments, 79, 2008, Digital control of force microscope
cantilevers using a field programmable gate array, This report describes a
cantilever controller for magnetic resonance force microscopy based on a
field programmable gate array, along with the hardware and software used
to integrate the controller into an experiment. The controller is
assembled from a low-cost commercially available software defined radio
device and libraries of open-source software. The controller includes a
digital filter comprising two cascaded second-order sections ``biquads''
which together can implement transfer functions for optimal cantilever
controllers. An appendix in this report shows how to calculate filter
coefficients for an optimal controller from measured cantilever
characteristics. The controller also includes an input multiplexer and
adder used in calibration protocols. Filter coefficients and multiplexer
settings can be set and adjusted by control software while an experiment
is running. The input is sampled at 64 MHz; the sampling frequency in the
filters can be divided down under software control to achieve a good match
with filter characteristics. Data reported here were sampled at 500 kHz,
chosen for acoustic cantilevers with resonant frequencies near 8 kHz.
Inputs are digitized with 12 bit resolution, and outputs are digitized
with 14 bits. The experiment software is organized as a client and server
to make it easy to adapt the controller to different experiments. The
server encapsulates the details of controller hardware organization,
connection technology, filter architecture, and number representation. The
same server could be used in any experiment, while a different client
encodes the particulars of each experiment. sidles
cantilever control FPGA
Klein200810 200810 PHYSICAL REVIEW B
78, 144410 100, 8We review how a magnetic-resonance force microscope LRF
can be applied to perform ferromagnetic resonance spectroscopy of
individual submicron-size samples. We restrict our attention to a thorough
study of the spin-wave eigenmodes excited in Permalloy (Py) disks
patterned out of the same 43.3-nm-thin film. The disks have a diameter of
either 1.0 or 0.5 um and are quasisaturated by a perpendicularly applied
magnetic field. It is shown that quantitative spectroscopic information
can be extracted from the MRFM measurements. In particular, the data are
extensively compared with complementary approximate models of the
dynamical susceptibility: a two-dimensional analytical model, which
assumes a homogeneous magnetization dynamics along the thickness, and i a
full three-dimensional micromagnetic simulation, which assumes a
homogeneous magnetization dynamics below a characteristic length scale c
and approximates the cylindrical sample volume by a discretized
representation with regular cubic mesh of lateral size c=3.9 nm. In our
analysis, the distortions due to a breaking of the axial symmetry are
taken into account; both models incorporating the possibility of a small
misalignment between the applied field and the normal of the disks.
slavin thin films
analytical models references Wigen and
Hammel
Dobigeon200809 200809 arXiv.org,
arXiv:0809.3650v1, Hierarchical Bayesian sparse image reconstruction with
application to MRFM, This paper presents a hierarchical Bayesian model to
reconstruct sparse images when the observations are obtained from linear
transformations and corrupted by an additive white Gaussian noise. Our
hierarchical Bayes model is well suited to such naturally sparse image
applications as it seamlessly accounts for properties such as sparsity and
positivity of the image via appropriate Bayes priors. We propose a prior
that is based on a weighted mixture of a positive exponential distribution
and a mass at zero. The prior has hyperparameters that are tuned
automatically by marginalization over the hierarchical Bayesian model. To
overcome the complexity of the posterior distribution, a Gibbs sampling
strategy is proposed. The Gibbs samples can be used to estimate the image
to be recovered, e.g. by maximizing the estimated posterior distribution.
In our fully Bayesian approach the posteriors of all the parameters are
available. Thus our algorithm provides more information than other
previously proposed sparse reconstruction methods that only give a point
estimate. The performance of our hierarchical Bayesian sparse
reconstruction method is illustrated on synthetic and real data collected
from a tobacco virus sample using a prototype MRFM instrument.
hero image reconstruction
Bayesian
Ren200809200809Physics Letter A 372,
We report a Boltzmann polarization nuclear spins detection of cycle
adiabatic inversion based on resonance slice thickness modulation. The
nano-scale localized spin scanning NMRFM is applied using spins locked and
anti-locked in the cycling frame. We also create a number of polarization
spins among 10^12 observing the spin relaxation and dipole-dipole
interaction at gradient field 1520 T/m. The changes of nuclear spin signal
intensity and relaxation time could be evidence for the nuclear collective
excitation and predictions of nuclear spin collective excitation
energy. ren polarization
relaxation references the usual suspects
Fong200807 200807 Appl Phys Lett 93,
012506 2008, doi.org/10.1063/1.2955826, Manipulating spins by cantilever
synchronized frequency modulation: A variable resolution magnetic
resonance force microscope, We report a new spin manipulation protocol for
periodically reversing the sample magnetization for magnetic resonance
force microscopy LRF. The protocol modulates the microwave excitation
frequency synchronously with the position of the oscillating detection
cantilever, thus allowing manipulation of the spin magnetization
independent of both magnetic field gradient strength and cantilever
response time. This allows continuous variation of the detected sample
volume and is effective regardless of spin relaxation rate. This enhanced
flexibility improves the utility of MRFM as a generally applicable imaging
and characterization tool. hammel
rf modulation COSMO
Degen200806200806 Appl Phys Lett 92,
24311, DOI:10.1063/1.2943282, Scanning magnetic field microscope with a
diamond single-spin sensor, We describe a scanning device where a single
spin is used as an ultrasensitive, nanoscale magnetic field sensor. As
this "probe spin" we consider a single nitrogen-vacancy defect center in a
diamond nanocrystal, attached to the tip of the scanning device. Changes
in the local field seen by the probe spin are detected by optically
monitoring its electron paramagnetic resonance transition. The
room-temperature scanning device may be useful for performing nanoscale
magnetic resonance imaging and spectroscopy, and for the characterization
of magnetic nanostructures down to the single atom level.
rugar, references valuable conversations with Rugar et al
probespin detection
Poggio200806
200806
Nature Physics 15 June 2008, doi:10.1038/nphys992, An off-board
quantum point contact as a sensitive detector of cantilever motion, Recent
advances in the fabrication of microelectromechanical systems and their
evolution into nanoelectromechanical systems have enabled researchers to
measure extremely small forces, masses and displacements. In particular,
researchers have developed position transducers with resolution
approaching the uncertainty limit set by quantum mechanics. The
achievement of such resolution has implications not only for the detection
of quantum behaviour in mechanical systems, but also for a variety of
other precision experiments including the bounding of deviations from
newtonian gravity at short distances6 and the measurement of single
spins. Here, we demonstrate the use of a quantum point contact as a
sensitive displacement detector capable of sensing the low-temperature
thermal motion of a nearby micromechanical cantilever. Advantages of this
approach include versatility due to its off-board design, compatibility
with nanoscale oscillators and, with further development, the potential to
achieve quantum-limited displacement detection.
rugar, with Jura, Degen, Topinka, and Goldhaber-Gordon
quantum
transducer
Nazaretski200805 200805 Appl Phys
Lett, 92, 214104, Spatial characterization of the magnetic field profile
of a probe tip used in magnetic resonance force microscopy, We have
developed the experimental approach to characterize spatial distribution
of the magnetic field produced by cantilever tips used in magnetic
resonance force microscopy LRF. We performed MRFM measurements on a well
characterized diphenylpicrylhydrazyl film and mapped the three-dimensional
field profile produced by a Nd2Fe14B probe tip. Using our technique, field
profiles of arbitrarily shaped probe magnets can be imaged.
hammel tips field
relaxation
Obukhov200803
200803
Phys Rev Lett 100, 197601, Local Ferromagnetic Resonance
Imaging with Magnetic Resonance Force Microscopy, We report
nanoscale scanned probe ferromagnetic resonance force microscopy
(FMRFM) imaging of
individual ferromagnetic microstructures. This reveals the mechanism for
high spatial resolution in FMRFM imaging: the strongly inhomogeneous local magnetic field of the cantilever mounted
micromagnetic probe magnet used in FMRFM enables selective, local
excitation of ferromagnetic resonance (FMR). This approach, demonstrated
here in individual permalloy disks, is straightforwardly extended to
excitation of localized FMR modes, and hence imaging in extended
films. Hammel
FMR magnetoelectronic
volume
Degen200712
200712
Phys Rev Lett 99, 250601, Role of Spin Noise in the Detection of
Nanoscale Ensembles of Nuclear Spins, When probing nuclear spins in
materials on the nanometer scale, random fluctuations of the spin
polarization will exceed the mean Boltzmann polarization for sample
volumes below about (100 nm). In this Letter, we use magnetic
resonance force microscopy to observe nuclear spin fluctuations in
real time. We show how reproducible measurements of the
polarization variance can be obtained by controlling the spin
correlation time and rapidly sampling a large number of independent
spin configurations. This allows significant improvement in the
signal-to-noise ratio for nanometer-scale magnetic resonance
imaging.
rugar
spin
polarization
SNR
Eberhardt200711
200711
Phys Rev Lett, PRL 99, 227603, Direct Observation of Nuclear
Spin Diffusion in Real Space, Images directly visualizing the
spatial spin-diffusion process are reported. The measurements were
performed using a magnetic resonance force microscope. The field
gradient associated with the forcedetection experiment is large enough to
affect the spin dynamics and a modified kinetics of the spindiffusion
process is observed. The effects of the gradient were compensated
for by a pulse scheme and a pure Zeeman diffusion rate constant of D=(6.2
+/- 0.7) * 10^-12cm^2/s in CaF2 was observed. 10 12 cm2=s in CaF2
was observed.Meier spin
diffusion
ETH Zurich, EPFL Lausanne
Gozzini196309 196309 Proc XIIth
Colloque Ampere, Bordeaux 17-21 September, 1963, Electronic Magnetic
Resonance and Solid Dielectrics, report on the theory and the experimental
results obtained in the study of the polarimetric phenomena in the
radiofrequency region. Several effect related to the magnetic resonance,
in which the polarisation of the electromagnetic field plays an essential
role, are examined, and their interest for the study and the detection of
the resonance is stressed ascoli
resonance dielectrics Universita di
Pisa
Alzetta196401 196401
Proc XIIth Colloque Ampere Bordeaux, 17-21 September, 1963, Eds. R.
Servant and A. Charru, Electronic Magnetic Resonance and Solid
Dielectrics, sent by Ascoli with the note that the first experiment was
done, ``by Gozzini and Gerardo Alzetta, an exceptional experimentalist
still active in Pisa, Un Effett Mecanique Lie a la Resonance
Paramagnetique alzetta, with Gozzini
fnmr history Universita de Pisa
Schmidt196609 196609
J Appl Phys, High-sensitivity magnetic resonance by bolometer
detection schmidt resonance
bolometer Ecole Polytechnique
Schmidt196609 196609 J Appl
Phys, vol 37, no 10, High-Sensitivity Magnetic Resonance by Bolometer
Detection schmidt esr
bolometer Ecole Polytechnique
Alzetta196712 196712 Il Nuovo Cimento, Serie
X, Vol 52, p392-402, Ascoli sent me a .pdf after I saw it cited in, Nestle
- The idea of mechanically detected magnetic resonance was first suggested
by a group in Pisa and demonstrated with a macro torsion setup similar to
the one used in the detection of the Einstein-de Haas effect. Ascoli
writes that, ``Ennio Arimondo, the younger of us, made the line shape
theory/calculation vs. power and for many photon transitions.''
Paramagnetic Resonance Experiments at Low Fields with Angular-Momentum
Detection alzetta, with Ascoli, Arimondo, and Gozzini
fnmr history
Universita de Pisa
Alzetta196803a
196803 Il Nuovo Cimento, Serie X, Vol 54, p107-115 Ascoli
sent this with the note that, ``My contribution has been essentially in
the set-up improvement (differential photodetector, lock-in detection)''}
alzetta, with Arimondo, and Ascoli fnmr
history Universita de Pisa
Alzetta196803b 196804 Il
Nuovo Cimento, Serie X, Vol. 54, p163-164, Observation of Paramagnetic
Resonance by Thermal Noise, Ascoli sent this with the note that, ``My
contribution has been essentially in the set-up improvement (differential
photodetector, lock-in detection)'' alzetta, with
Arimondo, and Ascoli fnmr history
Universita de Pisa
Turkevich197201 197201 J Chem Phys, early
DPPH ESR article mrfm sample
dpph Princeton University
Saenz198711 198711 J Appl Phys,
Observation of magnetic forces with an AFM grutter, with
Garcia, Meyer, Heinzelmann, Wiesendanger, Rosenthaler, Hidber, and
Guntherodt magnetic afm
Universidad Autonoma de Madrid, Institut fur Physik
Mamin198907 198907 Appl Phys
Lett, vol 55, no 3, Magnetic force microscopy of thin Permalloy films
rugar, with Stern, Fontana, and Kasiraj
magnetic image IBM Almaden
Hobbs198911 198911 Appl Phys
Lett, vol 55, no 22, p 2357, Magnetic force microscopy with 25nm
resolution using phase detection by lock-in amplifier and nickel tip at
IBM Watson Center - cites Mamin and Rugar, but is not really MRFM
rugar, cited by Abraham, and Wickramasinghe mfm
lock-in IBM Watson Center
Rugar198912 198912 Appl Phys
Lett, fiber-optic interferometer for AFM rugar, with
Mamin, and Guethner optics afm
IBM Almaden
Sidles199106
199106 Appl Phys Lett, This article was the
first to demonstrate the theoretical possibility of imaging the atomic
structure of biological molecules by what is now called magnetic resonance
force microscopy. Among the key concepts introduced in this article are
the idea of using force to detect magnetic resonance via the excitation of
ultra-small mechanical oscillators, the idea that the required force could
be obtained by imposing field gradients of order tens of Gauss per
Angstrom, the idea that microscale ferromagnets are a source of such
gradients, and the idea that `slices' thinner than an Angstrom can be
resolved by such gradients. With hindsight this article also includes some
embarassing idiosyncracies: the proposed cantilevers are orders of
magnitude smaller than those presently employed, all detection is by
piezoelectric means rather than optical, and most peculiarly, the phrase
`force microscope' appears nowhere in the article (at the time I had never
seen a force microscope). sidles mrfm
theory University of Washington
Rugar199108 199108
Phys Rev Lett, Mechanical Parametric Amplification and Thermomechanical
Noise Squeezing rugar, with Grutter afm
models IBM Almaden
Sidles199202 199202 Phys Rev
Lett, This article showed that single spin samples are effectively
self-polarizing, by the same quantum mechanism which ensures that the spin
polarization measured in a Stern-Gerlach experiment is always $/pm 100/%$.
The article notes that ``Oscillator-coupled NMR detection differs
substantially from inductive NMR detection, and it is necessary to
`unlearn' some conventional wisdom regarding inductive NMR. In
oscillator-based detection it is not necessary to polarize samples prior
to taking a measurement, nor is it necessary to wait for a period $T_1$
after each measurement for polarization to equilibriate. $/pi/2$ pulses
are not required to initiate spin precession, because any initial spin
state couples energy into the oscillator.'' These quantum phenomena are
essential to planned single-electron and single-nucleon imaging
experiments. sidles spin
coupling University of Washington
Grutter199208 199208
Ultramicroscopy, vol 47, no 4, p393-399, Magnetic microscopy of magnetic
materials, In this paper we give a brief summary of the basic principles
of MFM. Some typical experimental results are discussed to demonstrate the
potential, limitations and future perspectives of this technique.
rugar, with Mamin mrfm models
Universitat Basel, IMB Almaden
Sidles199208 199208 Rev Sci Instrum,
This lengthy article presented the first detailed design analysis of a
single-nucleon MRFM imaging device. As requested by reviewers, this
article calculated MRFM signal strength by three methods: (1) spin and
cantilever both treated classically, (2) cantilever treated classically,
spin treated quantum mechanically, (3) a full quantum mechanical analysis
of spin and cantilever as a combined quantum system. The three approaches
were shown to yield equivalent results (as expected). The effects of
spin-spin interactions in target nuclei were calculated quantum
mechanically. This article concludes with a detailed numerical simulation
of the signal resulting from an atomic-resolution MRFM scan of C13 nuclei
within an isotopically-labeled CD4 receptor embedded in a cell membrane.
See Figure 2 ... wave packet Figure 3 ... Stern-Gerlach splitting Figure 4
... environmental interactions equation, the spin-oscillator Hamiltonian
discussed in this 1992 article is fully equivalent to the Jaynes-Cummings
Hamiltonian of quantum optics. The authors did not recognize this
equivalence. sidles, with Garbini, and Drobny
mrfm systems University of
Washington
Rugar199212 199212
Nature, letters, Conventional techniques for measuring
magnetic resonance involve the detection of electromagnetic signals
induced in a coil or microwave cavity by the collective precession of
magnetic moments (from nuclei or electrons) excited by an alternating
magnetic field. In a different approach1, isolated electron spins have
been detected by scanning tunnelling microscopy, with the spin precession
inducing a radiofrequency modulation in the tunnelling current. Here, we
describe a new and extremely sensitive method of detection, the principles
of which derive from magnetic force microscopy and a recent proposal by
one of us (JAS). We measure the small, oscillatory magnetic force (10^-14
N) acting on a paramagnetic sample (a few grains of
diphenylpicrylhydrazil, weighing less than 30 ng) which has been excited
into magnetic resonance in the presence of an inhomogeneous magnetic
field. This force is detected by optically sensing the angstrom-scale
vibration of a micromechanical cantilever on which the sample is mounted.
The sensitivity of this technique to the spatial distribution of the spins
suggests that mechanical detection of magnetic resonance has the potential
for imaging microscopic samples in three dimensions. So far, we have
achieved a spatial resolution of 19 microns in one dimension.
rugar, with Yannoni, and Sidles mrfm
experiments IBM Almaden, University of
Washington
Sidles199301* 199301
Proc Microscopy Society of America, p6-7, The theoretical
possibilities and experimental realities of imaging molecular structure by
magnetic resonance force microscopy is presented in this paper. This
technique offers three main advantages: the imaging is noncontact and
nondestructive; the imaging field is three-dimensional and reaches below
the scanned surface; the theory of magnetic resonance interactions
provides a basis for the design and operation of imaging devices. With new
molecular microscopes, it is expected that molecular biologists can obtain
images showing the full three-dimensional structure of the molecules they
are studying in situ. sidles mrfm
proceedings University of Washington
Sidles199305 199305
Phys Rev Lett, This brief article ``compares the sensitivity of
inductive and mechanical methods for detecting magnetic resonance'' and
concludes that ``as mechanical oscillators are made smaller, their ability
to detect magnetic resonance signals improves, such that existing force
microscope cantilevers provide a viable alternative to inductive methods
for detecting magnetic resonance.'' The essential argument is inductive
detection devices work worse as they are made smaller, which MRFM devices
work better, which is why microscale MRFM devices can in principle achieve
single spin detection and imaging. sidles, with Rugar
mrfm snr
University of Washington, IBM Almaden
Zuger199311 199311 Appl Phys Lett, First
images from a magnetic resonance force microscope, We describe a new
magnetic resonance imaging technique based on the measurement of magnetic
force acting between a magnetic tip and the resonantly excited spins in
the sample. Magnetic resonance force maps of the sample are formed by
scanning the tip with respect to the sample while measuring the
angstrom-scale vibration of a microcantilever holding the sample.
Real-space spin density information can be recovered from the force maps
by using a simple image reconstruction technique. The technique was
demonstrated for electron spin resonance in micrometer size particles of
diphenyipicrylhydrazil. Using a tip that generates a field gradient of 4.3
G/um, a lateral resolution of 5um, and an axial resolution of 1um was
achieved. rugar mrfm
experiments IBM Almaden
Sidles199401* 199401 Mat Res Soc, Symposium
Proceedings: Determining Nanoscale Physical Properties of Materials by
Microscopy and Spectroscopy, Vol. 332: 449-460, M. Sarikaya, H. K.
Wickramasinghe and M. Isaacson, eds. 1994, This conference proceedings
discusses the technical problems attendant to single spin detection. More
complete coverage of this same material is presented in our subsequent
1995 Rev Mod Phys article sidles, with Garbini
mrfm review University of
Washington
Zuger199405 199405
J Appl Phys, Magnetic resonance detection and imaging using
force microscope techniques (invited,) We describe the principles and
imaging characteristics of a new type of high resolution magnetic
resonance microscopy. Magnetic resonance is detected by measuring a small
oscillating magnetic force acting between the spins in a sample and a
nearby ferromagnetic particle. The oscillating magnetic force is generated
by polarizing the spins in the magnetic field and then modulating the
sample magnetization using magnetic resonance techniques. The oscillating
magnetic force is detected by sensing the angstrom-scale vibration of a
micromechanical cantilever on which the sample is mounted. High spatial
resolution is achieved as a result of the narrowness of the magnetic
resonance spectral response and the large magnetic field gradient
generated by the ferromagnetic particle. Electron paramagnetic resonance
images are presented that demonstrate axial resolution on the order of 1um
and lateral resolution on the order of 5um. Submicron resolution can be
expected with straightforward technical improvements.
rugar mrfm description
IBM Almaden
Rugar199406
199406 Science, Force detection of nuclear magnetic
resonance rugar, with Zuger, Hoen, Yannoni, Vieth, and
Kendrick mrfm experiments
IBM Almaden
Hammel199501
199501 J Low Temp Phys, Vol 10, no 12, Sub-surface imaging
with the magnetic resonance force microscope, This article marks the
appearance in print of the third group to independently perform an MRFM
experiment, under the auspices of Los Alamos National Laboratory
hammel, with Zhang Z, Moore, and Roukes mrfm
experiments LANL, Caltech
Sidles199501 199501 Rev Mod
Phys, This is the first review article ever published on magnetic
resonance force microscopy. By the proposer's deliberate intent, it is
organized as two articles in one: an outer nontechnical `wrapper'
describing the biomedical context of MRFM (Sections I-II and X-XI)
surrounding an inner technical core (Sections III-X) that gives a
reasonably comprehensive set of expressions for computing signal and noise
levels in a broad class of MRFM experiments. The central theme of the
review is the feasibility in principle of detecting single electron
moments by a concatenation of already-existing technologies.
sidles, with Garbini, Bruland, Rugar, Zuger, Hoen, and Yannoni
mrfm review
University of Washington, IBM Almaden
Yannoni199501* 199501 Encyclopedia for
Magnetic Resonance. Magnetic resonance force microscopy. In D. M. Grant
and R. K. Harris, editors, John Wiley and Sons Ltd., Sussex, 1995 - can't
find copy rugar, with Zuger and Sidles
mrfm encyclopedia IBM Almaden,
University of Washington
Yannoni199501*
199501 Brazilian Journal of Physics, 25(4):417D25,
Magnetic resonance force microscopy: recent results - can't find copy
rugar, with Zuger, Wago, Hoen, and Vieth
mrfm results IBM Almaden
Bruland199504 199504 Rev Sci
Instrum, vol 68, no 4, Anharmonic modulation for noise reduction in
magnetic resonance force microscopy, This article presents a new
modulation technique for noise reduction in magnetic resonance force
microscopy. Applied fields are modulated at frequencies that are not
rational fractions of the cantilever resonant frequency, thus avoiding
overtones that contribute to the noise level. An on-resonance signal is
obtained because the nonlinear sample magnetization acts as a frqequency
mixer of the two modulation frequencies, producing a net force modulation
at the cantilever resonant frequency. These techniques are experimentally
demonstrated using electron spin resonance in a less than 15mg sample of
diphenylpicrylhydrazil. sidles, with Krzystek and Garbini
noise modulation
University of Washington
Yannoni199601
199601 Encyclopedia of Nuclear Magnetic Resonance,
eds. Grant, D. M. and Harris, R. K. (Wiley, New York), Early paper
detailing the possibility for NMR using MRFM, praises Sidles' insight in
the first two paragraphs rugar, with Zuger, and Sidles
cantilever dissipation
IBM Almaden, University of Washington
Zuger199602 199602 J Appl Phys,
Three-dimensional imaging with a nuclear magnetic resonance force
microscope, A magnetic resonance force microscope was used to demonstrate
three dimensional nuclear magnetic resonance imaging with micrometer-scale
spatial resolution. The sample was mounted on a silicon nitride cantilever
that served as a micromechanical force sensor. A nearby magnetic tip
generated a field gradient. A three-dimensional magnetic resonance force
map of the 1H spins in the sample was produced by lateral scanning of the
magnetic tip relative to the sample and by varying the rf frequency of the
spin excitation. The real-space spin density of the sample was
reconstructed from the force map by means of a deconvolution technique.
The spatial resolution achieved in the experiment was 3um in the axial
direction. rugar, with Hoen, and Yannoni
mrfm experiments IBM Almaden
Wago199603 199603
J Vac Sci Tech, A low-temperature magnetic resonance force microscope MRFM
has been built and a force sensitivity of 8x10^-17 N/AHz has been achieved
using a single-crystal silicon cantilever with a Q of 200,000 at 6 K.
Nuclear magnetic resonance NMR of 19F was measured via force detection in
a 1% Nd-doped CaF2 sample mounted on the cantilever. Cyclic adiabatic
inversion of the 19F nuclear spins was performed using a frequency
modulated radio frequency field at 100 MHz, resulting in an oscillatory
magnetic force that excited the cantilever vibration. NMR force signals
were measured in the temperature range between 12 and 40 K. The MRFM
technique was also used to measure some basic NMR properties such as
spin-lattice relaxation time. rugar, with Zuger, Kendrick,
and Yannoni nmr relaxation
IBM Almaden
Zhang199604
199604 Appl Phys Lett, Observation of ferromagnetic
resonance in a microscopic sample using magnetic resonance force
microscopy, We report the observation of a ferromagnetic resonance signal
arising from a microscopic 20um x 40um particle of thin 3um yttrium iron
garnet film using magnetic resonance force microscopy MRFM. The large
signal intensity in the resonance spectra suggests that MRFM could become
a powerful microscopic ferromagnetic resonance technique with a micron or
sub-micron resolution. We also observe a very strong nonresonance signal
which occurs in the field regime where the sample magnetization readily
reorients in response to the modulation of the magnetic field. This signal
will be the main noise source in applications where a magnet is mounted on
the cantilever. hammel, with Wigen
ferromagnetic experiments LANL, Ohio
State University
Bruland199608
199608 J Appl Phys, vol 84, no 4, Optimal control of force
microscope cantilevers. II. Magnetic coupling implementation, We describe
the implementation of optimal controllers for damping the motion of
cantilevers used in magnetic resonance force microscopy. We demonstrate
that optimal control is achievable and that torsional magnetic coupling
provides an effective actuation method. Cantilever Brownian vibrational
amplitude was reduced from 2 to 0.16 and resonant quality was reduced
from 2000 to 5. Applied control fields were sufficiently small that they
would not affect magnetic resonance phenomena. sidles,
with Garbini, and Doughterty cantilever
control University of Washington
Dougherty199608 199608 Meas
Sci Tech, vol 7, Detection of AC magnetic signals by parametric mode
coupling in a mechanical oscillator, Parametric coupling has been
demonstrated between mechanical vibration modes in a magnet-tipped
microcantilever. An external magnetic field, coupled to the magnetic tip,
pumps the effective spring constant at a frequency which is either the sum
or the difference of the mode resonance frequencies. The presence of the
pump field can be detected by driving one mode and observing the
parametrically pumped excitation of the other mode, even though the pump
frequency is off-resonance with respect to both mechanical modes. In a
room temperature experimental realization, the magnetic flux coupling the
pump field to the tip was approximately one flux quantum and the dominant
noise source was the thermal vibration of the cantilever. Parametric mode
coupling is a useful new design option in magnetic resonance force
microscopy, whereby modulation is advantageously performed off-resonance
to avoid parasitic excitations caused by stray couplings. Parametric
coupling also provides a low-noise technique for amplifying mechanical
oscillations. The reported experiment completes the set of all possible
force microscope interaction Hamiltonians up to third order in
time-dependent fields. sidles, with Bruland, and Garbini
oscillator signals
University of Washington
Garbini199608
199608 J Appl Phys, vol 80, no 4, Optimal control of
force microscope cantilevers I, Controller design, In magnetic resonance
force microscopy MRFM experiments, magnetic forces couple to the motion of
microscale cantilever beams. Extension of MRFM to the detection of single
electrons will require both unprecedented force sensitivity and motional
stability of the cantilever. We describe the principles and performance of
optimal cantilever motion control. The method accounts for inherent noise
processes and practical application of control forces. We show that active
feedback control improves cantilever motional stability, enabling
instrument designs of much higher sensitivity and faster imaging than
passive designs. Experimental results of implemented cantilever control
systems are presented in Part II. sidles, with Bruland and
Dougherty cantilever control
University of Washington
Zhang199609 199609 Rev Sci Instrum,
Application of a novel rf coil design to the magnetic resonance force
microscope, We report a rf coil design based on the Alderman Grant coil
called the modified Alderman Grant coil MAGC, and demonstrate its efficacy
in the magnetic resonance force microscope MRFM. The rf field of the MAGC
has a magnitude comparable to that of a solenoidal coil of similar size
for the same input power! but the coil has a much smaller inductance. This
is advantageous in electron spin resonance MRFM experiments which would
benefit from rf frequencies in excess of 1000 MHz. The open design of the
MAGC is also advantageous because it provides superior access to the
sample mounted on a mechanical cantilever by the optical fiber and
permanent magnet and so allows the sample to be placed at the center of
the coil. hammel, with Moore rf
coil LANL, Ohio State University
Rugar199610 199610
Welch Foundation, General MRFM paper delivered in presentation by Dan to
the Welch Foundation in Houston rugar, with Wago, Botkin,
Zuger, Vieth, Kendrick, and Yannoni mrfm
model IBM Almaden
Varela199610 199610 Meas Sci Technol, early
MFM article that references Rugar valera, with Farley
mfm experiments
Manchester Metropolitan University
Ascoli199612
199612 Appl Phys Lett, 69, p3920,
Micromechanical detection of magnetic resonance by angular momentum
absorption alzetta, with Baschieri, Frediani, Lenci,
Martinelli, Celli, and Pardi mrfm
models Consiglio Nazionale delle Ricerche
Dougherty199701 199701 Cell
Vision, vol 4, no 2, proceedings, Sensitivity Calculations for Subcellular
Spin Imaging by Magnetic Resonance Force Microscopy
sidles, with Bruland, Garbini, and Leath mrfm
noise University of Washington
Yordanov199701 199701
Fresenius J Anal Chem, Quantitative spectrophotometric and
EPR-determination of 1,1-diphenyl-2-picryl-hydrazyl (DPPH)
mrfm sample dpph
Bulgarian Academy of Sciences
Zhang199701*
199701 IEEE transactions on Magnetics,
Magnetic resonance force microscopy with a permanent magnet on the
cantilever, volume 33, number 5, pages 4147--9 hammel
mrfm experiments
LANL
Salapaka199703 199703
J Appl Phys, A multi-mode analysis of micro-cantilever
dynamics is presented. We derive the power spectral density of the
cantilever displacement due to a thermal noise source and predict the
cantilevers's fundamental resonant frequency and higher harmonics. The
first mode in the multi-mode model is equivalent to the traditional
single-mode model. Experimental results obtained with a silicon nitride
cantilever at 300 K are in excellent qualitative agreement with the
multi-mode model. The multi-mode model may be used to obtain accurate
values of the cantilever properties such as the elastic modulus, effective
mass, thickness and moment of inertia. salapaka, with
Bergh, Lai, Majumdar, and McFarland cantilever
experiments UC Santa Barbara, UC Berkeley
Wago199704 199704
Rev Sci Instrum, Electron spin resonance ESR of phosphorus-doped silicon
was detected using a low temperature magnetic resonance force microscope
MRFM. Force-detected ESR spectra were obtained using an amplitude or
frequency modulated microwave field to cyclically saturate the spin
magnetization. For a sample containing 4x10^18 phosphorus atoms/cm3, a
single strong ESR line was observed. For a sample containing 8x10^16
phosphorus atoms/cm3, a pair of lines split by the 42 G 31P hyperfine
interaction was observed. This result demonstrates the possibility of
using MRFM techniques for spectroscopic purposes. rugar,
with Zuger, Wegener, Kendrick, and Yannoni esr
experiments IBM Almaden
Schaff199705 199705 Appl Phys Lett,
Magnetic resonance force microscopy MRFM is a new microscopy technique
that combines the spin selective detection of nuclear or electron spin
resonance with the high spatial resolution of atomic force microscopy. In
this letter we present MRFM measurements on a three-layer system in the
micron range. We detected the one-dimensional distribution of proton spins
in a sample that consisted of two-ammonium sulphate layers and an
intermediate layer of sodium chloride. The experiments were done at room
temperature and normal pressure, in contrast to earlier MRFM measurements
that have been carried out in vacuum at room temperature or low
temperatures. veeman mrfm
experiments University of Duisburg
Hammel199706
199706
The magnetic resonance force microscope: A new microscopic probe or
magnetic materials, in Frontiers in Magnetism of Reduced Dimension
Systems, V.G. Bar'yakhtar, P.E. Wigen, and N.A. Lesnik, eds, NATO ASI
Proceedings, Crimea, Ukraine, May 25-June 3, 1997
hammel
materials
magnetism
Ohio, Caltech
Stowe199707 199707
Appl Phys
Lett, A measured force resolution of 5.6x10^-18 N/AHz at 4.8 K in vacuum
using a single-crystal silicon cantilever only 600 mu thick is
demonstrated. The spring constant of this cantilever was 6.5x10^-6 N/m, or
more than 1000 times smaller than that of typical atomic force microscope
cantilevers. The cantilever fabrication includes the integration of
in-line tips so that the cantilever can be oriented perpendicular to a
sample surface. This orientation helps suppress cantilever snap-in so that
high force sensitivity can be realized for tip-sample distances less than
100 angstroms. rugar, with Yasumura, Kenny, Botkin, and
Wago cantilever dynamics
IBM Almaden, Stanford University
Naughton199711 199711 Rev Sci Instrum, The
technique of cantilever magnetometry is shown to be functional in pulsed
magnetic fields. Employing micromachined single crystal silicon
cantilevers and capacitance detection, we demonstrated a utilizable
sensitivity to magnetic moment of 2.5x10^-12 Am2 in magnetic fields to 36
T, representing an improvement of more than a factor of 10 over competing
technologies. Torque magnetization measurements on microcrystals of
anisotropic superconductors are presented as evidence of the feasibility
of the technique in long pulse magnets of pulse duration 0.1 1 s.
naughton, with Ulmet, Narjis, Askenazy, Chaparala, and Hope
cantilever experiments
State University of New York, Service National des Champs
Magnetiques Pulses, INSA, National High Magnetic Field Laboratory
Leskowitz199801 199801
Solid State Nuclear Magnetic Resonance, vol 11, p73-86, Force
detected magnetic resonance with the BOOMERANG protocol
weitekamp, with Madsen nmr gradient
Caltech
Wago199801
199801 Phys Rev B, Electron-spin resonance of E8
centers in vitreous silica was studied using force-detection techniques at
temperatures down to 5 K. Cyclic adiabatic inversion of electron spins was
performed by frequency modulation of the applied microwave magnetic field.
This produced an oscillatory magnetic force between the electron spins and
a nearby permanent magnet, resulting in the vibration of a cantilever on
which the sample was mounted. By pulsing the microwave field prior to the
force-detection sequence, nutation of the spins could be observed. Spin
echoes were observed mechanically using a modified echo-pulse sequence.
The decay of magnetization during cyclic adiabatic inversion was also
studied and is discussed in terms of utility for future single-spin
detection experiments. rugar, with Botkin, and Yannoni
rf experiments IBM
Almaden
Yasumura199801* 199801
Proc Technical Digest, Solid-State Sensor and Actuator
Workshop, Transducer Research Foundation, Cleveland Heights, pages 65-70,
A study of microcantilever quality factor - can't find copy
rugar, with Stowe, Chow, Pfaff, and Kenny
cantilever quality IBM Almaden,
Stanford University
Chui199803
199803 J MEMS, 7, 1, Low-Stiffness Silicon Cantilevers with
Integrated Heaters and Piezoresistive Sensors for High-Density AFM
Thermomechanical Data Storage rugar
cantilever afm
Bruland199804 199804 J Appl Phys, vol
83, no 8, Optimal control of ultrasoft cantilevers for force microscopy,
The goals of optimal control in force microscopy are: 1) to obtain
favorable cantilever dynamic properties and 2) to control the cantilever
to a desired amplitude, while 3) exerting as little control force as
possible, and 4) preserving the force signal-to-noise ratio of the
uncontrolled cantilever. This article describes the experimental
implementation of an optimal controller that achieves these goals. The
application of this controller to an ultrasoft cantilever with spring
constant of 110 mN/m at 10 K reduced the resonant quality from 15 000 to
220, reduced the Brownian amplitude from 11.2 to 1.4, used less than
7x10^-17 N of control effort, left the force sensitivity unaltered at
9.8x10^-18 N/A Hz, and demonstrated feedback control can force cantilever
motion to track a reference input. sidles, with Garbini,
and Dougherty cantilever control
University of Washington
Wago199805 199805 Appl Phys Lett, A magnetic
resonance force microscope with a tip-on-cantilever configuration was
used to compare imaging characteristics of paramagnetic and ferromagnetic
samples. Three-dimensional electron paramagnetic resonance EPR imaging of
diphenylpicrylhydrazil DPPH particles was accomplished by scanning the
sample in two dimensions while stepping an external field. The EPR force
map showed broad response reflecting the size and shape of the sample,
allowing a three-dimensional real-space magnetization image to be
successfully reconstructed. In contrast to the EPR case, ferromagnetic
resonance imaging of a micron scale yttrium iron garnet sample showed no
significant line broadening despite the strong field gradient (~10 G/um).
Two-dimensional force maps revealed spatial dependence of magnetostatic
and magnetoelastic modes. rugar, with Botkin, and Yannoni
ferromagnetic paramagnetic
IBM Almaden
Barrett199806
199806 J Appl Phys, vol 83, no 11, Design and
construction of a sensitive nuclear magnetic resonance force microscope,
We report our progress in the design and construction of a sensitive and
versatile nuclear magnetic resonance force microscope. Improvements over
previous designs include the use of higher Q of 10^5-10^7, single-crystal
double-torsional mechanical oscillators for force detection and the
development of extremely convenient positioning and approach capabilities.
We describe both a demonstration experiment using large 1cm torsional
oscillators and the micromachining of the small 100um torsional
oscillators. markert, with Miers, Sommer, and Mochizuki
mrfm models
University of Texas
Suh199808
199808 J Vac Sci Tech, Lateral one-dimensional imaging of
cobalt Co films by means of microscopic ferromagnetic resonance FMR
detected using the magnetic resonance force microscope MRFM is
demonstrated. A novel approach involving scanning a localized magnetic
probe is shown to enable FMR imaging in spite of the broad resonance
linewidth. We introduce a spatially selective local field by means of a
small, magnetically polarized spherical crystallite of yttrium iron garnet
YIG. Using MRFM-detected FMR signals from a sample consisting of two Co
films, we can resolve the 20um lateral separation between the films. The
results can be qualitatively understood by consideration of the calculated
spatial profiles of the magnetic field generated by the YIG sphere.
roukes, with Hammel, Zhang, Midzor, and Childress
cantilever design LANL,
Caltech, University of Florida Gainesville
Streckeisen199810 199810 Appl Phys A, A
novel sample preparation technique for deposition of small volumes from
the liquid phase is described. Samples with diameters as small as 0:5 mm
were created with this technique. A series of cantilever geometries was
manufactured, with the aim of optimizing the Q-factor. Force sensitivities
of 8 10^-17 N=pHz were achieved at room temperature, which is a
considerable improvement over commercial cantilevers. Mechanisms which
determine Q-factors are discussed briefly. Quantitative understanding of
MRFM is absolutely necessary. Calculations of the magnetic field and field
gradients for several types of permanent magnets are presented.
rast, with Wattinger, Meyer, Vettiger, Gerber, and Guntherodt
sample preparation
University of Basel, IBM Zurich
Zhang199810
199810 Appl Phys Lett, Ferromagnetic
resonance force microscopy on microscopic cobalt single layer films, We
report mechanical detection of ferromagnetic resonance FMR signals from
microscopic Co single layer thin films using a magnetic resonance force
microscope MRFM. Variations in the magnetic anisotropy field and the
inhomogeneity of were clearly observed in the FMR spectra of microscopic
Co thin films 500 and 1000 thick and 40x200um^2 in lateral extent. This
demonstrates the important potential that MRFM detection of FMR holds for
microscopic characterization of spatial distribution of magnetic
properties in magnetic layered materials and devices.
hammel, with Midzor, Roukes, and Childress fmr
experiments LANL, Caltech, University of
Florida Gainesville
Bruland199811
199811 Appl Phys Lett, vol 73, no 21, Force-detected
magnetic resonance in a field gradient of 250,000 Tesla per meter We
report the detection of slice-selective electron spin resonance with an
external magnetic field gradient comparable to local interatomic
gradients, using the techniques of magnetic resonance force microscopy. An
applied microwave field modulated the spin-gradient force between a
paramagnetic DPPH sample and a micrometer-scale ferromagnetic tip on a
force microscope cantilever. A sensitivity equivalent to 184 polarized
electron moments in a one-Hertz detection bandwidth was attained. We
mapped the tip magnetic field with a resonant slice thickness of order one
nanometer, thereby demonstrating magnetic resonance on length scales
comparable to molecular dimensions. sidles, with
Dougherty, Garbini, and Chao resonance
measure University of Washington
Wei199811 199811 preprint,
It is proposed that nuclear (or electron) spins in a trapped molecule
would be well isolated from the environment and the state of each spin can
be measured by means of mechanical detection of magnetic resonance.
Therefore molecular traps make an entirely new approach possible for
spin-resonance quantum computation which can be conveniently scaled up.
In the context of magnetic resonance spectroscopy, a molecular trap
promises the ultimate sensitivity for single spin detection and an
unprecedented spectral resolution as well. wei, with Xue
molecular traps
McGill University
Zhang199811
199811 Solid State Nuclear Magnetic Resonance, Magnetic
resonance force microscopy with a ferromagnetic tip mounted on the force
detector, The Magnetic Resonance Force Microscope MRFM presents the
opportunity for a magnetic resonance imaging probe with ultra-high,
potentially atomic scale, resolution. The successful application of this
technique in detection of nuclear magnetic, electron-spin and
ferromagnetic resonance FMR highlights its significant potential. We
discuss the capabilities of the MRFM with particular emphasis on the
detection of FMR using MRFM techniques. A crucial remaining challenge in
the development of the magnetic resonance force microscope MRFM is to
place the magnetic probe on the mechanical resonator. We address the
problem of spurious detector response arising from interactions between
the magnetic tip and various external applied fields. We show that
miniature, magnetically-polarized Nd 2Fe14 B particles show promise as
magnetic probe tips. Our experience indicates it will be important to
minimize the total polarized moment of the magnetic tip and to ensure that
the applied fields are as uniform as possible. hammel
fmr review LANL
Marohn199812 199812
Appl Phys Lett, vol 73, no 25, An optimal magnetic tip
configuration for magnetic-resonance force microscopy of microscale buried
features, To date, magnetic-resonance force microscopes employing a
magnetic-field gradient source mounted to a microcantilever have suffered
from a deleterious dependence of the effective cantilever spring constant
on the external magnetic field. A magnet-on-tip configuration is
introduced in which this dependence has been decreased by at least 200
fold, making it feasible to perform arbitrary-sample micron-scale magnetic
resonance force microscopy at very high magnetic field.
Alternating-gradient cantilever magnetometry is used to quantify the
effect and to prove that the existing model of the tip-field interaction
is only qualitatively correct. A model is proposed which quantitatively
describes the tip-field interaction in the traditional tip configuration.
marohn, with Fainchtein, and Smith
magnetometry experiments Johns
Hopkins University, US ARL
Pelekhov199901
199901 Rev Sci Instrum, We report on the
design and performance of an atomic force microscope which operates at
temperatures down to 20 mK and in magnetic fields up to 9 T. The scan
range at low temperatures is 4 mmx4 mm. The instrument features a
piezoelectric linear motor for vertical coarse approach, and a horizontal
sample translation stage with a 2 mmx2 mm range. A fiber interferometer is
used to detect the force-sensing cantilever displacement. The performance
demonstrated includes the ability to detect single atomic steps on a
graphite surface at 4.2 K and the ability to locate and image nanometer
scale electronic devices at millikelvin temperatures.
pelekhov, with Becker and Nunes magnetic
afm Dartmouth College
Chui199803 199903 Microscale
Thermophysical Engineering, 3, Intrinsic-Carrier Thermal Runaway in
Silicon Microcantilevers rugar
cantilever heat
Alzetta199907 199907 J Mag Res, 141,
p148-158, Simultaneous Micromechanical and Electromagnetic Detection of
Electron Paramagnetic Resonance, also cited in, Nestle, Mechanically
detected NMR - integration of Ruskell's sample on tip within a normal ESR
spectrometer architecture alzetta, with Ascoli, Baschieri,
Bertolini, Betti, de Masi, Frediani, Lenci, Martinelli, and Scalari
esr models
Universita de Pisa
Ruskell199907
199907 J Appl Phys, We have developed magnetic resonance
force microscopy for quantitative measurements of magnetic fields. A
microscopic particle attached near the end of a microcantilever serves as
the field sensing probe. We have demonstrated two-dimensional field
mapping with a lateral resolution of 3.2um and a field resolution of 0.19
mT 1.9 G. The instrument holds considerable promise for field mapping with
spatial resolution better than 0.1um at room temperature. Applications
include field mapping of magnetic recording heads.
moreland, with Ruskell, and Lohndorf mrfm
field NIST, Colorado
Bruland199909 199909 Rev Sci Instrum, vol
70, no 9, Thermal tuning of a fiber-optic interferometer for maximum
sensitivity, We describe a fiber-optic interferometer that employs
wavelength changes to achieve maximum sensitivity. Wavelength changes are
induced by adjusting the operating temperature of the laser, eliminating
the need for an actuator to vary the spacing between the sensing fiber and
the object to be monitored. The instrument and techniques described are
suitable for cryogenic, high vacuum applications such as magnetic
resonance force microscopy, where space is limited and micromanipulation
can be challenging. The noise floor of 1.6x10^-3 nm/AHz is adequate for
monitoring subangstrom displacement of force microscope cantilevers.
sidles, with Garbini, Dougherty, Chao and Jensen
interfere heat University
of Washington
Marohn199910 199910
J App Phys, vol 86, no 8, Mechanical modulation of sample
magnetization in magnetic resonance force microscopy, We have developed a
mechanical method for modulating sample magnetization in magnetic
resonance force microscopy experiments. A small-amplitude, low-frequency
dithering of a magnetic field gradient source relative to a sample is used
to create an oscillating magnetic field at the sample, which leads to a
modulation of magnetization in rf-irradiated samples by magnetic
resonance. Using this technique in concert with modulating rf power, we
have achieved a 10 000 decrease in a sensitivity-limiting spurious
response of microcantilevers to rf fields in sample-on-cantilever magnetic
resonance force microscopy experiments. This mechanical implementation of
anharmonic modulation is especially well suited for low power and
vacuum applications, and is unique in its ability to modulate sample
magnetization in magnet-on cantilever experiments where the cantilever
frequency is found to be a strong function of magnetic field.
marohn, with Fainchtein, and Smith modulation
experiments Johns Hopkins
University, US ARL
Stowe199911
199911 Appl Phys Lett, Noncontact damping of a cantilever
vibrating near a silicon surface was used to measure localized electrical
dissipation. The dependence of the damping on tip-sample distance, applied
voltage, carrier mobility, and dopant density was studied for n- and
p-type silicon samples with dopant densities of 10^14 - 10^18 cm^-3.
Dopant imaging with 150 nm spatial resolution was demonstrated.
rugar, with Kenny, and Thomson cantilever
damping Stanford University, IBM
Almaden, University of Manitoba
Dougherty200001
200001 J Mag Res, vol 143, The Bloch
Equations in High-Gradient Magnetic Resonance Force Microscopy: Theory and
Experiment, We report theory and observations of paramagnetic resonance in
a measured field gradient of 44,000 T per meter by the technique of
magnetic resonance force microscopy (MRFM). Resonance was induced in a
dilute solid solution of diphenylpicrylhydrazyl in polystyrene at 77 and
10 K by an amplitude-modulated microwave field. This modulated the force
between resonant sample spins and a micrometer-scale SmCo magnetic tip on
a force microscope cantilever. The force signals were typically of order
10 fN, and were detected above a thermal noise floor of 80 aN per root
hertz at 10 K, equivalent to a magnetic moment noise of 200 mB per root
hertz of bandwidth. Resonance saturation was readily observed. Starting
with the Bloch equations, we derived simple analytic expressions for the
predicted cantilever signal amplitudes and T1-dependent phase lags, valid
at low microwave power levels. For power levels below saturation, the data
were in good agreement with the Bloch equation predictions, while above
saturation the measured force increased more slowly with power than
predicted. Several ESR mechanisms which might lead to non-Bloch dynamics
in the MRFM environment are reviewed. Spin-relaxation mechanisms are also
reviewed. A detailed description of the experimental apparatus is offered.
sidles, with Bruland, Chao, Garbini, and Jensen
nmr experiments University
of Washington
Berman200002 200002
Phys Rev B, vol 61, no 5, solid state mrfm with hammel
berman, with Hammel solid state
models LANL, Polytechnic University
Klein200002 200002
European Physical Journal B, vol 17, p57-68, Mechanical detection of
nuclear spin relaxation in a micron-size crystal, A room temperature
nuclear magnetic resonance force microscope (MRFM), tted in a 1 tesla
electromagnet, has been used to measure the nuclear spin relaxation of 1H
in a micron-size (70 ng) crystal of ammonium sulfate. NMR sequences,
combining both pulsed and continuous wave radio frequency fields, have
allowed us to measure mechanically T2 and T1, the transverse and
longitudinal spin relaxation times. Because two spin species with
different T1 values are measured in our 7 um thick crystal, magnetic
resonance imaging of their spatial distribution inside the sample section
have been performed. To understand quantitatively the measured signal, we
carefully study the influence of spin-lattice relaxation and
non-adiabaticity of the continuous-wave sequence on the intensity and time
dependence of the detected signal. alloul, with Naletov
nmr experiments
Ecole Polytechnique, Kazan State University
Lohndorf200002 200002 Appl Phys Lett, vol
76, no 9, Ferromagnetic resonance detection with a torsion-mode
atomic-force microscope, We have developed a ferromagnetic resonance FMR
instrument based on a torsion-mode atomic-force microscope AFM. The
instrument measures the torque on a magnetized thin film in a static
out-of-plane field perpendicular to the film surface. The magnetic film is
deposited onto an AFM microcantilever. FMR measurements are performed at a
fixed microwave frequency of 9.15 GHz with a sweeping in-plane field. At
the FMR condition, the change in the average in-plane magnetization of the
film is at a maximum corresponding to a maximum change in the torque on
the AFM cantilever. Our instrument is capable of measuring fluctuations of
in-plane magnetization of 63.3 A/m of NiFe film samples with a total
volume of 1.1x10^-10 cm3. Given a signal-to-noise ratio of 40, we estimate
a magnetic moment sensitivity of 1.7x10^-16 A/m^2.
moreland, with Kabos afm resonance
NIST, Colorado
Berman200003
200003 Superlattices and Microstructures,
vol 27, solid state quantum computing with doolen berman,
with Doolen, and Tsifrinovich solid state
models LANL, Polytechnic University
Yasumura200003 200003 J
MEMS, Micromechanical cantilevers are commonly used for detection of small
forces in microelectromechanical sensors (e.g., accelerometers) and in
scientific instruments (e.g., atomic force microscopes). A fundamental
limit to the detection of small forces is imposed by thermomechanical
noise, the mechanical analog of Johnson noise, which is governed by
dissipation of mechanical energy. This paper reports on measurements of
the mechanical quality factor for arrays of silicon-nitride, polysilicon,
and single-crystal silicon cantilevers. By studying the dependence of on
cantilever material, geometry, and surface treatments, significant insight
into dissipation mechanisms has been obtained. For submicron-thick
cantilevers, is found to decrease with decreasing cantilever thickness,
indicating surface loss mechanisms. For single-crystal silicon
cantilevers, significant increase in room temperature is obtained after
700 C heat treatment in either N2 or forming gas. At low temperatures,
silicon cantilevers exhibit a minimum in at approximately 135K, possibly
due to a surface-related relaxation process. Thermoelastic dissipation is
not a factor for submicron-thick cantilevers, but is shown to be
significant for silicon-nitride cantilevers as thin as 2.3 m. Index
Terms Cantilever, force sensor, mechanical dissipation, micromechanical
resonator, quality factor, surface losses. rugar, with
Stowe, Chow, Pfafman, Kenny, and Stipe cantilever
dissipation Stanford University, IBM
Almaden
SmithG200004 200004
EPSRC, Grant application, Application of Magnetic Response
Force Microscopy in the Development of a National High Field EST Centre
smithG ESR structure
St. Andrews
Hannay200005
200005 J Appl Phys, vol 87, no 9, Thermal
field fluctuations in a magnetic tip, implications for magnetic resonance
force microscopy, Thermally excited magnetic fluctuations are fundamental
to the behavior of small ferromagnetic particles and have practical
consequences for the proposed detection of individual spins by magnetic
resonance force microscopy MRFM. In particular, fluctuating fields from a
nearby magnetic tip can increase the relaxation rate of spins in a sample
if there is significant spectral density of field fluctuation at the
Larmor frequency of the target spin. As an initial step toward
understanding this issue, magnetic field fluctuations have been simulated
which emanate from a magnetic tip with dimensions 60 nm x 60 nm x 2 mm. It
was found that the fluctuations in a cobalt magnetic tip were too strong
for MRFM experiments aimed at detecting individual electron spins.
However, the results obtained for a PrFeB tip fell within the tolerance
required. rugar, with Chantrell
relaxation models University of
Wales, IBM Almaden
Midzor200005
200005 J App Phys, vol 87, no 9, Imaging mechanisms of
force detected FMR microscopy, We demonstrate spatial resolution of
ferromagnetic resonance in a microscopic sample of YIG using ferromagnetic
resonance force microscopy FMRFM. Measurements were performed on a small
single crystal YIG film grown on a GGG substrate, roughly rectangular in
shape 20 umx150 um and 3 um thick. The perpendicular and parallel force
geometries of FMRFM, in conjunction with an external bias field both
parallel and perpendicular to the film, were used to scan the sample. This
enabled the detection of strong signals, even at atmospheric pressure and
room temperature. The fundamental and higher-order magnetostatic modes
were observed to have 26-29 Gauss separation. The intensity of these modes
exhibited spatial variation as the magnetic tip was scanned over the
sample, and this behavior is qualitatively explained by DE theory. An
improved fabrication method for magnet on cantilever was employed, which
yielded a spatial resolution of 15 mm. These results demonstrate the
potential of FMRFM for investigating the spatial dependence of
ferromagnetic resonance, and for studying the anisotropy fields and
exchange coupling effects within multilayer films and small magnetic
systems. roukes, with Wigen, Pelekhov, Chen, and Hammel
ferromagnetic imaging
Caltech, Ohio State University, LANL
Berman200006 200006 Phys Rev B, vol 61, no
21, Solid-state nuclear-spin quantum computer based on magnetic resonance
force microscopy, modified approach to single spin detection
berman, with Hammel, Doolen, and Tsifinovich
spin models LANL, Polytechnic
University
Pastuchenko200007
200007 Single Molecules, vol 1, p165-170, Effects of
Viscoelastic Cantilever - Sample Interaction on Laser Beam Deflection in
MAC Mode MRFM, Amplitude and phase of a laser beam reflected from an
oscillating cantilever tip in Magnetic AC (MAC) mode of Molecular
Recognition Force Microscopy (MRFM) are theoretically investigated by
taking into account both the spring constant of the
tip/crosslinker/antibody/antigen complex and hydrodynamical cantilever -
sample interaction. Analytical results are obtained based on some
geometrical specifications of a typical cantilever - sample MRFM system.
For high frequencies of the driving magnetic field the laser beam
deflection is mainly due to the cantilever deformation and the amplitude
of the tip oscillations is strongly damped. Therefore high frequencies
are not favourable for biologically relevant studies.
pastushenko, with Hinterdorfer, Kienberger, Borken, and Schindler
cantilever sensor
Johannes-Kepler University of Linz
Rast200007
200007 Rev Sci Instum, In atomic force
microscopy cantilevers are used to detect forces caused by interactions
between probing tip and sample. The minimum forces which can be detected
with commercial sensors are typically in the range of 10^-12 N. In the
future, the aim will be to construct sensors with improved sensitivities
to detect forces in the range of 10^-18 N. These sensors could be used for
mass spectroscopy or magnetic resonance force microscopy. Achieving this
goal requires smaller sensors and increased quality factor Q. In this
article we describe a model to characterize the dynamics of cantilevers of
each eigenmode. In contrast to previous models, the damping is treated
rigorously in the calculations. rast, with Wattinger,
Gysin, and Meyer cantilever qm
Institut fur Physik Klingelbergstrasse
Moreland200008 200008 Rev
Sci Inst, We describe a new type of ferromagnetic resonance FMR
spectroscopy that is based on a calorimeter sensor. We use an atomic force
microscopy cantilever coated with a ferromagnetic thin film as a
bimaterial sensor to measure absorption of microwaves at 9.17 GHz. The
spectra show a peak in the cantilever deflection as a function of applied
magnetic field corresponding to a peak in the absorbed microwave power
that occurs at the FMR resonance of the ferromagnetic film. The saturation
magnetization Meff and the damping factor awere determined from the FMR
microwave absorption spectra for Co, NiFe, and Ni thin films. The data
correlate well with conventional FMR spectra taken with a tuned cavity
spectrometer. Our instrument can detect magnetic moments as small as
1.3x10^-12Am2 (1.3x10^-9 emu) with prospects for sensitivity improvements
to the 1x10^-16Am2 (1x10^-12 emu) level. The technique provides a
potentially superior way to make quantitative measurements of saturation
magnetization of thin-film samples with very small total magnetic moments.
moreland, with Lohndorf, Kabos, and McMichael
fmr frequency NIST,
Colorado, NIST, Maryland
Moreland200101
200101 NIST, GO-31, We describe an instrument for in
situ monitoring of the magnetic moment of a thin film during deposition
with sub- monolayer sensitivity. The instrument measures the magnetic
torque on a film as it is being deposited onto a micro-cantilever excited
near its mechanical resonance. Dynamic feedback is used to balance the
magnetic torque by applying a mechanical force at the base of the
cantilever. moreland, with Beall, and Russek
thin film magnetics NIST,
Colorado
Nestle200101 200101
Prog Nuc Mag Res Spec, MRFM review article
review mrfm review
University of Leipzig, Gerhard-Mercator-Universitat
Berman200103 200103 Phys Rev Lett,
vol 86, no 13, mrfm quantum computing with tellurium donor silicon
berman, with Hammel, Doolen, and Tsifinovich
sample models LANL, Polytechnic
University
Rugar200103 200103
Appl Phys A, Materials Science and Processing, We report
detection of forces as small as 1.4 x 10^-18 N in a 1 Hz bandwidth using
ultrathin silicon cantilevers operating at liquid helium temperatures.
rugar, with Stipe, Mamin, Yannoni, Yasumura, and Kenny
mrfm experiments
IBM Almaden, Stanford University
Smith200104
200104 Rev Sci Instrum, We describe the
design and operation of a cryogenic magnetic resonance force microscope
for detecting nuclear magnetic resonance. Instrument critical details are
enumerated, including fabrication of a positionable radio-frequency coil,
detection of angstrom-level microcantilever oscillations using an optical
fiber interferometer, design of a compact fiber/cantilever alignment
system, temperature compensation of the fiber/cantilever gap, control of
sample temperature, and vibration isolation. Additionally, experimental
protocols and sample specific considerations such as spin relaxation times
are addressed. 19F nuclear magnetic resonance data obtained from a
Nd-doped CaF2 sample are presented. smith, with Marohn,
and Harrell mrfm experiments
US ARL, University of Maryland, USMA West Point
Mamin200111 200111
Appl Phys Lett, vol 79, no 20, Sub-attonewton force detection at
millikelvin temperatures, A 290-nm-thick single-crystal silicon cantilever
has been cooled in vacuum to a temperature of 110mK in order reduce its
thermal motion and thereby improve the achievable force resolution. Since
the thermal conductivity of the silicon cantilever is extremely low at
millikelvin temperatures, an improved optical fiber interferometer was
developed to measure the subangstrom thermal motion with optical powers as
low as 2 nW. At the lowest temperature, the cantilever exhibited a quality
factor of 150 000 and achieved a noise temperature of 220 mK, with a
corresponding force noise of 820 zN in a 1 Hz bandwidth.
rugar cantilever experiments
IBM Almaden
Stipe200112
200112 Phys Rev Lett, Magnetic resonance
force microscopy was used to study the behavior of small ensembles of
unpaired electron spins in silica near a micrometer-size ferromagnetic
tip. Using a cantilever-driven spin manipulation protocol and a magnetic
field gradient greater than 10^5 T/m, signals from as few as 100 net spins
within a 20 nm thick resonant slice could be studied. A sixfold increase
in the spin-lattice relaxation rate was found within 800 nm of the
ferromagnet, while no effect due to silica surface proximity was detected.
The results are interpreted in terms of Larmor-frequency magnetic field
fluctuations emanating from the ferromagnet. rugar, with
Mamin, Yannoni, Stowe, and Kenny mrfm
experiments IBM Almaden, Stanford University
Marohn200201 200201
Proposal, NIH, 1. Detect nuclear magnetic resonance in a new way, as a
change in the spring constant of a magnetically tipped microcantilever.
2. Fabricate and characterize nanomagnets suitable for single-proton
cantilever detected magnetic resonance, and explore experimentally the
minimum forces and spring constant changes that can be detected when a
thin, ultrasensitive, silicon microcantilever is brought close to a
surface. 3. Develop and test magnetic resonance imaging protocols suited
to small ensembles of nuclear spins. marohn
mrfm experiments Cornell
University
Reports2002_NSF_Garbini
200201 NSF, report, landweber algorithm picture
sidles image
deconvolution University of Washington
Verhagen200201 200201 J Am
Chem Soc, In this report, we show the first MRFM results for quadrupolar
nuclei. Kentgens, with Wittlin, Hilbers, and van Kempen
nuclear spin
University of Nijmegen
Berman200203
200203 preprint, Stationary cantilever vibrations in
the oscillating cantilever-driven adiabatic reversals - magnetic resonance
force microscopy technique, early OSCAR description
berman, with Kamenev and Tsifrinovich qm
models LANL, Polytechnic University
Pelekhov200203 200203 Proc
SPIE, The fabrication and operation of a Solid State Quantum Computer
(SSQC) presents very formidable challenges; primary amongst these are: (1)
the characterization and control of the fabrication process of the device
during its construction and (2) the readout of the computational result.
Magnetic Resonance Force Microscopy (MRFM) - a novel scanning probe
technique based on mechanical detection of magnetic resonance - provides
an attractive means of addressing these requirements. The sensitivity of
the MRFM significantly exceeds that of conventional magnetic resonance
measurement methods, and it has the potential for single electron spin
detection. Moreover, the MRFM is capable of true 3D subsurface imaging.
These features will make MRFM an invaluable tool for the implementation of
a spin-based QC. Here we present the general principles of MRFM operation,
the current status of its development and indicate future directions for
its improvement. pelekhov, with Martin, Suter, Reagor, and
Hammel qm computer
LANL
Thurber200203 200203
Appl Phys Lett, We applied the technique of force-detected nuclear
magnetic resonance to observe 71Ga, 69Ga, and 75As in GaAs. The nuclear
spin-lattice relaxation time is 21 +/- 5 min for 69Ga at 5 K and 4.6 T. We
have exploited this long relaxation time to first create and then observe
spatially varying nuclear spin polarization within the sample,
demonstrating a form of contrast for magnetic resonance force microscopy.
Such nuclear spin contrast could be used to indirectly image electron spin
polarization in GaAs-based spintronic devices. smith, with
Harrell, and Fainchtein GaAs
relaxation US ARL, USMA West Point, Johns Hopkins
University
Ladd200207 200207
Phys Rev Lett, vol 89, no, All-silicon computer,
solid-state implementation of a quantum computer with a thin bridge whose
oscillations provide readout via magnetic resonance force microscopy
(MRFM) yamamoto, with Goldman, Yamaguchi, Abe, and Itoh
solid-state qubits
Stanford University, Keio University
Rugar200207
200207 internal, IBM, This document is meant
to provide a tutorial-style introduction to the classical dynamics of a
spin interacting with an MRFM cantilever. The material presented here
overlaps with our own previously published work, as well as the work of
Sidles and Berman et al. We first introduce the key equations governing
the spin and cantilever dynamics. We then present simplified results based
on perfect spin-locking while the spin is adiabatically inverted by the
oscillating cantilever. Finally we describe computer models that include
the effects of higher order cantilever modes. rugar, with
Budakian mrfm tutorial
IBM Almaden
Glover200208
200208 Reports Prog Phys, vol 65, p1489-1511, Limits to
magnetic resonance microscopy, This paper reviews the development of MRM
over the last decade with an emphasis on the current state of the art. The
fundamental principles of imaging and signal detection are examined to
determine the physical principles which limit the available resolution.
The limits are discussed with reference to liquid, solid and gas phase
microscopy. In each area, the novel approaches employed by researchers to
push back the limits of resolution are discussed. Although the limits to
resolution are well known, the developments and applications of MRM have
not reached their limit. review mrm
review University of Nottingham
Hammel200208 200208
Intl J Mod Phys B, vol 16, no 20-22, p 3378, Despite its citation
in a journal, it is entirely a one-page abstract for an MRFM presentation,
nothing new, but summarizes the MRFM method for non-destructive,
chemically specific, subsurface imaging with wide applicability to a wide
variety of materials. hammel mrfm
abstract LANL
Lang200209 200209 Nanomechanics from
atomic resolution to molecular recognition based on atomic force
microscopy technology (includes the globe-picture of the universe of
AFM-technologies that was published in the first issue of Nature
Nanotechnology.) meyer afm
history University of Basel, IBM Research
Zurich
Suter200211 200211
J Mag Res, Probe sample coupling in the Magnetic Resonance Force
Microscope roukes, with Pelekhov, and Hammel
sample coupling LANL,
Caltech
Barbic200212 200212
J Appl Phys, vol 92, no 12, p7345, Sample-detector coupling
in atomic resolution magnetic resonance diffraction - Barbic regularly
sends copies of his articles to our lab barbic, with
Scherer spin coupling
California State University Long Beach, Caltech
Metalidis200212 200212 Phys
Rev A, vol 66, 062102, Magnetic Casimir effect, The Casimir effect results
from alterations of the zero-point electromagnetic energy introduced by
boundary conditions. For ferromagnetic layers separated by vacuum or a
dielectric, such boundary conditions are influenced by the magneto-optical
Kerr effect. We will show that this gives rise to a long range magnetic
interaction and discuss the effect for two different configurations
magnetization parallel and perpendicular to the layers. Analytical
expressions are derived for two models and compared to numerical
calculations. Numerical calculations of the effect for Fe are also
presented and the possibility of an experimental observation of the
Casimir magnetic interaction is discussed. bruno
casimir effect
Max-Planck-Institut
Huang200301
200301 Nature, brief communications, col 421,
Nanoelectromechanical systems, Nanodevice motion at microwave frequencies
roukes, with Huang, Zorman, and Mehregany
oscillator signal Caltech,
Case Western Reserve University
Leskowitz200301
200301 Thesis Dissertation, describing force
detected NMR using BOOMERANG with comments on detection techniques by
Bloom on transverse stern-gerlach effect, Rabi molecular beam methods,
Pizarro and Weitekamp on NMR and ESR trapped ions, Sidles and Rugar and
Yannoni on MRFM, Leskowitz and Madsen and Weitekamp using BOOMERANG, and
Alzetta et al with absorption of angular momentum"The experimental trend
in MRFM has been toward everincreasing gradients, and as of this writing
MRFM has been performed with gradients as large as 250 kT/m. But, as we
have seen in Chapter 1, no gradients are in fact needed to observe
magnetic resonance with force detection, and there are very good reasons
for avoiding their use." weitekamp nmr
detection Caltech
Rugar200301 200301 internal, IBM,
Recent advances in cantilever-based force detection have allowed detection
of forces below an attonewton. We have applied this capability to the
study of dissipation and fluctuations in nanometer-scale systems. Our work
is largely motivated by our effort to extend magnetic resonance force
microscopy (MRFM) to single-spin sensitivity, where we have been
confronted with significant noise issues. Phenomena that we have studied
include magnetic moment fluctuations in nanoscale ferromagnets,
non-contact friction and force fluctuations near surfaces, and increased
electron spin relaxation rates observed when closely monitoring electron
spins by MRFM. The enhanced spin relaxation rate is believed to be caused
by Rabi frequency magnetic noise that is generated by thermal vibrations
of the high order cantilever modes. Overcoming these various noise issues
will be key to achieving single-spin quantum readout (23 refs.)
rugar noise dissipation
IBM Almaden
Thurber200301
200301 J Mag Res, We demonstrate
one-dimensional nuclear magnetic resonance imaging of the semiconductor
GaAs with 170nm slice separation and resolve two regions of reduced
nuclear spin polarization density separated by only 500 nm. This was
achieved by force detection of the magnetic resonance, magnetic resonance
force microscopy (MRFM), in combination with optical pumping to increase
the nuclear spin polarization. Optical pumping of the GaAs created spin
polarization up to 12 times larger than the thermal nuclear spin
polarization at 5K and 4T. The experiment was sensitive to sample volumes
of 50um^3 containing 4 x 10^11 71Ga/rootHz. These results demonstrate the
ability of force-detected magnetic resonance to apply magnetic resonance
imaging to semiconductor devices and other nanostructures.
smith, with Harrell GaAs polarization
US ARL, USMA West Point
Yip200301 200301 IEEE Transactions on Signal
Processing, In single spin Magnetic Resonance Force Microscopy (MRFM), the
objective is to detect the presence of an electron (or nuclear) spin in a
sample volume by measuring spin-induced attonewton forces using a
micromachined cantilever. In the OSCAR method of single spin MRFM, the
spins are manipulated by an external rf field to produce small periodic
deviations in the resonant frequency of the cantilever. These deviations
can be detected by frequency demodulation followed by conventional
amplitude or energy detection. In this paper, we present an alternative to
these detection methods, based on optimal detection theory and Gibbs
sampling. On the basis of simulations, we show that our detector
outperforms the conventional amplitude and energy detectors for realistic
MRFM operating conditions. For example, to achieve a 10% false alarm rate
and an 80% correct detection rate our detector has an 8 dB SNR advantage
as compared with the conventional amplitude or energy detectors.
Furthermore, at these detection rates it comes within 4 dB of the
omniscient matched-filter lower bound. Index Terms: Magnetic Resonance
Force Microscopy, OSCAR, single spin, optimal detection, cantilever,
random reversals, random telegraph, frequency shifts hero,
with Rugar, and Fessler detection
sampling University of Michigan, IMB Almaden
Abe200302 200302 J
Superconductivity: Incorporating Novel Magnetism, Vol. 16, No. 1, Solid
State Silicon NMR Quantum Computer, The number of identical nuclear spins
is so small that the conventional pickup coil could never be used for the
detection. Thus, we employ an alternative method for ensemble readout,
magnetic resonance force microscopy (MRFM), which is by far the most
sensitive NMR method available today - reference to Sidles 1995 Rev Mod
Phys and references therein yamamoto, with Itoh, Ladd,
Goldman, and Yamaguchi nmr computing
Keio University, Stanford University
Jacky200302 200302 preprint, Signal
processing and computing systems for magnetic resonance force microscopy
sidles, with Garbini computing
models University of Washington
Kempf200302 200302 Phys Rev
Lett, vol 90, no 8, Nanoscale Fourier-Transform imaging with Magnetic
Resonance Force Microscopy, We present a versatile method for Fourier
encoding the spatial distribution of spins detected by magnetic resonance
force microscopy. Shuttling a magnetic particle in synchrony with an rf
pulse sequence causes spins in a constant-field slice near the particle to
precess at a rate proportional to their x or y coordinate. A
two-dimensional spin-density map is recovered by a linear Fourier
transform of a set of integrated force signals. Performance of the rf
sequence is demonstrated experimentally and numerical simulations show
that the method can achieve nanoscale resolution. Our approach offers a
new route to manipulating spin wave functions down to the atomic scale.
marohn mrfm nmr
Cornell University
Moreland200302 200302 J Phys D: App Phys, I
review some of the novel methods for measuring ferromagnetic properties of
thin films based on micromechanical magnetometers and put them into
context relative to current research on nanomagnetism. Measurements rely
on the detection of mechanical forces or torques on thin films deposited
onto microcantilevers. Displacements of the cantilever are detected by
optical methods similar to those developed for atomic force microscopy.
High sensitivities are achieved by integrating the sample with the
detector, allowing magnetic measurements of samples with a total magnetic
moment smaller than that detectable with conventional magnetometers.
Cantilevers with low spring constants and high mechanical Q are essential
for these measurements. Sensitivities better than 105 muB are possible at
room temperature with the potential for single spin detection below 1 K,
where the thermomechanical noise of micromechanical sensors is
substantially reduced. moreland
ferromagnetic review NIST, Colorado
Mozyrsky200302 200302
Appl Phys Lett, We study relaxation of a spin in magnetic resonance
force microscopy MRFM experiments. We evaluate the relaxation rate for the
spin caused by high-frequency mechanical noise of the cantilever under the
conditions of adiabatic spin inversion. Confirmation of Rugar's
experiment, proposal for improved cantilevers with positional fluctuations
hammel, with Martin, and Pelekhov
cantilever relaxation LANL, Ohio
State University
Berman200303
200303 Phys Rev B, vol 67, 094425, Single-spin measurement
and decoherence in mrfm berman, with Borgonovi, Goan,
Gurvitz, and Tsifrinovich spin models
LANL, University of New South Wales, Polytechnic
University
Church200304 200304
Poster, DARPA MOSAIC Open House, Seattle,
Nanometer-Precision 2-lambda Interferometry For Closed-Loop MRFM Scan
Control Using Standard Telecommunications Hardware sidles,
with Garbini, and Dougherty interferometry
poster University of Washington
Rugar200304 200304 SPIE,
plenary paper, Feeling the noise in nanoscale systems: studies based on
ultrasensitive force detection rugar, with Budakian, Chui,
and Mamin spin ensembles
IBM Almaden
Thurber200304
200304 J Appl Phys, We demonstrate temperature
measurement of a sample attached to the end of a cantilever using
cantilever magnetometry of solid air contamination of the sample
surface. In experiments like our magnetic resonance force microscopy
~MRFM!, the sample is mounted at the end of a thin cantilever with small
thermal conductance. Thus, the sample can be at a significantly different
temperature than the bulk of the instrument. Using cantilever magnetometry
of the oxygen paramagnetism in solid air provides the temperature of the
sample, without any modifications to our MRFM apparatus.
smith, with Harrell temperature
experiments US ARL, USMA West Point
Hammel200305 200305 Proc IEEE, vol
91, no 5, p789, The Magnetic-Resonance Force Microscope: A New Tool for
High-Resolution, 3-D, Subsurface Scanned Probe Imaging, principles and
state-of-the-art descriptions of crystal oscillators and tips
hammel, with Pelekhov, Wigen, Gosnell, Midzor, and Roukes
mrfm experiments Ohio State
University, Pixon Inc, Caltech
Miller200305
200305 J Appl Phys, vol 93, no 10, External
field effects on the resonant frequency of magnetically capped oscillators
for magnetic resonance force microscopy, We study the resonant frequency
shift of CoPt-capped single-crystal silicon micro-oscillators when a
magnetic field is applied perpendicular to the magnetic film, as required
for application to nuclear magnetic resonance force microscopy. The
oscillator resonant frequencies show two distinct regimes of behavior. At
low fields, when the magnetic moment is nearly perpendicular to the
external field, the frequency decreases sharply with field, while at high
fields, when the moment and field are nearly aligned, the frequency
increases. We present models that accurately describe both behaviors. The
transition point between these two regimes scales with the volume of the
micromagnets. markert, with Mirsaidov, Messina, and Lee
oscillator crystals
University of Texas
Sidles200305
200305 Proc IEEE, vol 9, no 5, (invited) The
Classical and Quantum Theory of Thermal Magnetic Noise, with Applications
in Spintronics and Quantum Microscopy closely related to Joseph Chao's
thesis sidles, with Garbini, Dougherty, and Chao
magnetic noise University
of Washington
Berman200306 200306
preprint, We consider the process of spin relaxation in the
oscillating cantilever driven adiabatic reversals technique in
magnetic-resonance force microscopy. We simulated the spin relaxation
caused by thermal excitations of the high-frequency cantilever modes in
the region of the Rabi frequency of the spin subsystem. The minimum
relaxation time obtained in our simulations is greater than but of the
same order of magnitude as one measured in recent experiments. We
demonstrated that using a cantilever with nonuniform cross-sectional area
may significantly increase spin-relaxation time. with rugar
berman, with Gorshkov, and Tsifrinovich
relaxation frequency LANL,
Polytechnic University
Chui200306
200306 Proc Technical Digest, Solid-State Sensor and
Actuator Workshop, Transducer Research Foundation, Boston, Mass-loaded
cantilevers with suppressed higher-order magnetic resonance force
microscopy, We describe the design, fabrication and testing of massloaded
cantilevers for electron-spin magnetic resonance force microscopy. These
single-crystal silicon cantilevers are designed to have large gaps in
their thermal mode spectra so as to reduce thermal noise near the
electron-spin Rabi frequency. Each cantilever typically consists of a 2 um
thick mass suspended at the end of a 0.1 um thick hinge. The fabrication
process starts with an SOI wafer followed by selective silicon epitaxy,
cantilever patterning, and backside release. The focus of the process is
on precise thickness rugar, with Hishinuma, Budakian,
Mamin, and Kenny cantilever models
IBM Almaden, Stanford University
Church200306 200306 Thesis
Dissertation, Dual Wavelength Interferometry for Sample Position Control
in Magnetic Resonance Force Microscopy sidles
interferometry thesis
University of Washington
Salisbury200306
200306 Thesis Dissertation, Control of a
Piezoelectric Scanner for Magnetic Resonance Force Microscopy
sidles piezo control
University of Washington
Bargatin200309 200309 Phys Rev Lett, vol 91,
no 13, Nanomechanical Analog of a Laser: Amplification of Mechanical
Oscillations by Stimulated Zeeman Transitions roukes
oscillator models
Caltech
Berman200309 200309
Phys Rev B, vol 68, Spin relaxation caused by thermal
excitations of high frequency modes of cantilever vibrations, We consider
the process of spin relaxation in the oscillating cantilever-driven
adiabatic reversals technique in magnetic-resonance force microscopy. We
simulated the spin relaxation caused by thermal excitations of the
high-frequency cantilever modes in the region of the Rabi frequency of the
spin subsystem. The minimum relaxation time obtained in our simulations is
greater than but of the same order of magnitude as one measured in recent
experiments. We demonstrated that using a cantilever with nonuniform
cross-sectional area may significantly increase spin-relaxation time.
berman, with Gorshkov, Rugar, and Tsifrinovich
qm measurement LANL, IBM
Almaden, Polytechnic University
Brun200309
200309 Phys Rev A, vol 68, Realistic
simulations of single-spin nondemolition measurement by magnetic resonance
force microscopy, A requirement for many quantum computation schemes is
the ability to measure single spins. This paper examines one proposed
scheme: magnetic resonance force microscopy MRFM, including the effects of
thermal noise and back action from monitoring. We derive a simplified
equation using the adiabatic approximation and produce a stochastic pure
state unraveling which is useful for numerical simulations. We also
calculate the signal-to-noise ratio for single-spin measurement by MRFM,
using a quantum Langevin equation approach. - with goan
brun, with Goan qm measurement
Institute for Advanced Study, University of New South
Wales
Mamin200311 200311
Phys Rev Lett, vol 91, no 20, Detection and Manipulation of
Statistical Polarization in Small Spin Ensembles, We report the detection
of the statistical polarization in a small ensemble of electron spin
centers in SiO2 by magnetic resonance force microscopy. A novel detection
technique was employed that captures the statistical polarization and
cycles it between states that are either locked or anti-locked to the
effective field in the rotating frame. Using field gradients as high as 5
G/nm, we achieved a detection sensitivity equivalent to roughly 2 electron
spins, and observed ultralong spin-lock lifetimes, as long as 20 s. Given
a sufficient signal-to-noise ratio, this scheme should be extendable to
single electron spin detection. rugar, with Budakian, and
Chui polarization experiments
IBM Almaden
Sidles200311
200311 LIGO, P030055-B, Optical Torques in
Suspended Fabry-Perot Interferometers sidles, with Sigg
interferometry stability
University of Washington
Charbois200312
200312 Thesis Dissertation, in french,
Detection Mecanique de la Resonance Ferromagnetique, couldn't find an
email for the guy, but wrote a co-author who's interested in dielectrics
to see if I could correspond with Vincent - no response
charbois mrfm thesis
Universite Paris
Bruno200401
200401 unknown, Selected Results, The magnetic
Casimir force to be detected with the above setup is of the order of 100
fN for a distance of 10 nm, whereas a sensitivity of 0.5 fN has already
been achieved at room temperature in MRFM [rugar 1994] with prospects of
improving the sensitivity to the 10^-17 N range at room temperature or
even to the 10^-18 N range at liquid helium temperature [sidles 1995] We
therefore believe that the experimental test of the newly predicted
magnetic Casimir effect is indeed feasible. bruno, with
Metalidis casimir magnetics
Max Planck Institute
Budakian200401
200401 Phys Rev Lett, vol 92, no 3,
Suppression of Spin Diffusion near a Micron-Size Ferromagnet, We have used
the large gradients generated near the ferromagnetic tip of a magnetic
resonance force microscope to locally suppress spin diffusion in a silica
sample containing paramagnetic electron spins. By controlling the slice
location with respect to the tip, the magnetic field gradient was varied
from 0.01 to 36 mT= m, resulting in a fourfold decrease in T1 and a
similar decrease in T1. The observed dependence of the relaxation rates on
field gradient is consistent with the quenching of flip-flop interactions
that mediate the transport of magnetization between slow and fast relaxing
spins. budakian, with Mamin and Rugar
diffusion relaxation IBM Almaden
Goan200401 200401
Proc SPIE, vol 5276, p250, Single-spin measurement is an extremely
important challenge, and necessary for the future successful development
of several recent spin-based proposals for quantum information processing.
Magnetic resonance force microscopy (MRFM) has been suggested as a
promising technique for single-spin detection. We discuss how to read out
the quantum state of a single spin using the MRFM technique based on
cyclic adiabatic inversion (CAI). We include, in our analysis, a
measurement device (an optical interferometer) to monitor the position of
the cantilever, which then provides us with information of the spin state.
We consider various relevant sources of noise and taken into account the
effect of spin relaxation on the single-spin detection scheme. We also
present a realistic continuous measurement model, and discuss the
approximations and conditions to achieve a quantum nondemolition
measurement of a single spin by MRFM. Finally we will present some
simulation results for the single-spin measurement process.
goan, with Brun qm
measurement University of New South Wales, USC
Ting200507 200401
IEEE Transactions on Signal Processing - Manuscript T-SP-03127-2005.R1,
Near optimal signal detection for finite state Markov signals with
application to magnetic resonance force microscopy hero,
with Rugar, Yip, and Fessler mrfm
detectors University of Michigan, IBM Almaden
Tsuji200401 200401 J Mag
Res, Magnetic resonance imaging (MRI) is very useful spectroscopy to
visualize a three-dimensional (3D) real structure inside the sample
without physical destruction. The spatial resolution of the readily
available MRI spectrometer is, however, limited by a few ten to hundreds
of microns due to a technological boundary of generating larger magnetic
field gradient and to the insensitivity inherent to the inductive signal
detection. Magnetic resonance force microscopy (MRFM) is new alternative
MRI spectroscopy which is anticipated to significantly surpass the
conventional MRI in both resolution and sensitivity. We report two imaging
experiments on our MRFM spectrometer operated at room temperature and in
vacuum 10^-3 Pa. One is for 20 um liposome membrane labeled entirely by a
nitroxide imaging agent and the other for 15 um DPPH particles, both are
nearly the same size as that of human cell. The reconstructed images at
spatial resolution 1 um were in satisfactory agreement with the scanning
electron microscope images. The potential capability of visualizing
intrinsic radicals in the cell is suggested to investigate redox process
from a microscopic point of view. yoshinari, with Masumizu
mrfm samples JEOL
Berman200402 200402
preprint, A Model for Quantum Jumps in Magnetic Resonance Force
Microscopy berman, with Borgonovi, and Tsifrinovich
qm state LANL,
Universita Cattolico, Polytechnic University
Hory200301 200402 Proc IEEE, Workshop
Statistical Signal Processing, St. Louis, Frequency estimation derived
from a dynamical system analysis hero, with Ting
frequency estimation
University of Michigan
Hory200402
200402 preprint, Sequential probability ratio test for the
detection of a single electron spin in the OSCAR setup, The MRFM device is
a powerful setup for manipulating single electron spin in resonance in a
magnetic field. However, the real time observation of a resonating spin is
still an issue because of the very low SNR of the output signal. This
paper investigates the usability and the efficiency of sequential
detection schemes (the Sequential Probability Ratio Test) to decrease the
required integration time, in comparison to standard fixed time detection
schemes hero probability
signal University of Michigan
Gassman200403 200403 Phys
Rev B, 69, Quantum dissipative dynamics of the magnetic resonance force
microscope in the single-spin detection limit, We study a model of a
magnetic resonance force microscope MRFM based on the cyclic adiabatic
inversion technique as a high-resolution tool to detect single electron
spins. We investigate the quantum dynamics of spin and cantilever in the
presence of coupling to an environment. To obtain the reduced dynamics of
the combined system of spin and cantilever, we use the Feynman-Vernon
influence functional and get results valid at any temperature as well as
at arbitrary system-bath coupling strength. We propose that the MRFM can
be used as a quantum measurement device, i.e., not only to detect the
modulus of the spin but also its direction. gassman, with
Choi and Yi qm dissipation
University of Basel, Korea University, Korea Institute for
Advanced Study
Lenci200403 200403
Phys Rev B, vol 69, 094426, Magnetic resonance force
microscopy: Nonlinear processes and influence of relaxation times, The
phenomenon of the micromechanically detected magnetic resonance is
interpreted in terms of nonlinear processes at magnetic resonance. A close
analysi in the frequency domain of the irradiation and detection scheme
shows that the technique corresponds to a multiple irradiation with one or
more couple of frequencies separated by vc and to the detection of the
longitudinal component of magnetization oscillating at vc . The study of
longitudinal detection of magnetic resonance allows the direct measurement
of the spin-lattice relaxation time of samples. Samples of Mn21:MgO
prepared in order to obtain a mixture of spin systems with very different
relaxation processes were studied by electron-spin-resonance experiments
with micromechanical detection: measurements evidence a very strong
rejection of the system with lower longitudinal relaxation time. Direct
confirmation of the theoretical interpretation is obtained; in addition
the microscopy technique increases its contrast capability, adding the
possibility of determining maps of samples based on the distribution of
both concentration and longitudinal relaxation times of spin systems.
lenci, with Bertolini, Friselli, Martinelli, and Scalari
relaxation frequency
Nazionale delle Ricerche
Martin200403
200403 Phys Rev B, vol 69, Ground-state
cooling of mechanical resonators, We propose an application of a single
Cooper pair box (Josephson qubit) for active cooling of nanomechanical
resonators. Latest experiments with Josephson qubits demonstrated that
long coherence time of the order of microsecond can be achieved in special
symmetry points. Here we show that this level of coherence is su cient to
perform an analog of the well known in quantum optics laser cooling of a
nanomechanical resonator capacitively coupled to the qubit. By applying an
AC driving to the qubit, resonators with frequency of order 100 MHz and
quality factors higher than 103 can be e ciently cooled down to their
ground state, while lower frequency resonators can be cooled down to
micro-Kelvin temperatures. We also consider an alternative setup where
DC-voltage-induced Josephson oscillations play the role of the AC driving
and show that cooling is possible in this case as well.
martin, with Shnirman, Tian, and Zoller oscillator
heating LANL, Universitat Karlsruhe,
University of Innsbruck, Austrian Academy of Sciences
Barbic200404 200404 J Appl Phys, vol
95, no 7, p3598, Two-dimensional magnetic resonance tomographic microscopy
using ferromagnetic probes barbic, with Scherer
ferromagnetic microscopy
California State University Long Beach, Caltech
Berman200404 200404 preprint, Wave function
collapses in a single spin magnetic force microscopy
berman, with Borgonovi, and Tsifrinovich qm
state LANL, Universita Cattolico, Polytechnic
University
Blencowe200404 200404
Science, Perspectives, vol 304, p 56, Nanomechanical
Quantum Limits, introducing Knobel and Cleland's article on a resonating
crystal beam commentary beam
oscillators Dartmouth College
Kwasnik200404 200404 Thesis
Dissertation, Magnetic Resonance Force Microscopy Using Nanotubes and
Nanowires, dissertation for undergrad honors program at Boston College
naughton nanotube
cantilever Boston College
LaHay200404 200404 Science, Reports,
Approaching the quantum limit with a nanomechanical resonator
schwab, with Buu, and Camarota oscillator
experiments University of Maryland
Chao200405 200405
Rev Sci Instrum, vol 75, no 5, Nanometer-scale magnetic resonance imaging,
Magnetic resonance force microscopy MRFM images the three-dimensional
spatial distribution of resonant spins by mechanical force detection.
Image reconstruction in MRFM is challenging because the resonance occurs
in a strongly curved shell that extends beyond the scan range. In contrast
with conventional magnetic resonance imaging, where Fourier techniques
work well, the curved-shell resonant geometry inherent to MRFM requires
novel reconstruction methods. Here, we show the application of iterative
reconstruction in an electron spin resonance imaging experiment with 80 nm
voxels. The reconstructed image has a total scan volume of 0.5 cubic
micrometers, and was generated by a magnetic resonant shell with a
curvature radius of 2.3 mm. The imaged object was a paramagnetically doped
solid with an obliquely tilted surface. The reconstructed image correctly
identified the location and orientation of the surface, and mapped the
spin distribution within the solid. Applications of MRFM include three
dimensional nanometer-scale mapping of dopant distributions in
semiconductors, studies of magnetism of thin films, and spin diffusion
physics. An ultimate goal of MRFM is the direct observation of molecular
structure at the atomic sidles, with Dougherty, and
Garbini image deconvolution
University of Washington
Jenkins200405
200405 J Vac Sci Tech, vol 22, no 3, Batch
fabrication and characterization of ultrasensitive cantilevers with
submicron magnetic tips, We have batch fabricated ultrasensitive silicon
cantilevers with integrated submicron magnetic tips and have characterized
both their mechanical and magnetic properties. Cantilevers with spring
constants as small as 10^-5 N/m were fabricated, with quality factors in
the range of 2.5-3.5x10^4 and a force sensitivity as good as 64x10^-18
MHz^-1/2 at room temperature in vacuum. Cantilever spring constants were
measured by observing thermomechanical position fluctuations with a fiber
optic interferometer, while resonance frequencies and quality factors were
inferred from cantilever ring down transients. Polycrystalline nickel tips
as small as 1.2 um 30.4 um 30.2 um were fabricated on the cantilevers by
electron beam lithography, thermal evaporation, and lift-off. Tip magnetic
moments were inferred from the shift of the cantilever frequency versus
magnetic field and show a 0.60 +/- 0.12 T saturation magnetization,
indicating that less than 28 nm of oxide forms on the tips during
processing. Force sensitivity was demonstrated by using the cantilevers to
detect electron spin resonance at 115 K in the sample-on-cantilever
configuration. marohn, with DeFlores, Allen, Ng, Garner,
Kuehn, and Dawlaty cantilever
fabrication Cornell University
Ng200405 200405 preprint, App Phys
Lett marohn, with Jenkins magnetic
hysteresis Cornell University
Berman200406 200406
Phys Rev B, vol 69, 212408, Reduction of magnetic noise in magnetic
resonance force microscopy berman, with Gorshkov, and
Tsifrinovich qm noise
LANL, Polytechnic University
Garner200406 200406 Appl Phys Lett, vol 84,
no 25, Force-gradient detected nuclear magnetic resonance, We have
detected nuclear magnetic resonance in ^71GaAs by selectively inverting
71Ga spins to create a local force gradient which shifts the mechanical
resonance frequency of a nearby magnet tipped microcantilever. Employing a
low spring constant cantilever 60uN/m at 4.4K and 7T, we demonstrate a
magnetic moment sensitivity of 7.5x10^21 J/T, equal to the Curie Law
magnetization from 7.1x10^8 ^71Ga spins. The method obviates the need to
spin-lock sample magnetization during detection, allowing the signal to be
collected for a time approaching the full spin-lattice relaxation time.
marohn, with Kuehn, Dawlaty, and Jenkins
nmr sensitivity Cornell University
Peeples200406 200406
Thesis Dissertation, Vibration Suppression and Control of a
Piezoelectric Scanner with Application to Magnetic Resonance Force
Microscopy sidles scanner
control University of Washington
Hammel200407 200407 Nature,
News and Views, commentary on Rugar's single spin results
hammel mrfm commentary
Ohio State University
Ladd200407
200407 preprint, Quantum computation in a
crystal lattice, but presented in an MRFM context with NMR techniques that
rely on the spin gradient and mechanical lever yamamoto,
with Goldman, and Yamaguchi solid-state
crystals Stanford University, Keio University
Rugar200407 200407
Nature, letters, Here we report the detection of an individual electron
spin by MRFM. A spatial resolution of 25nm in one dimension was obtained
for an unpaired spin in silicon dioxide. The measured signal is consistent
with a model in which the spin is aligned parallel or anti-parallel to the
effective field, with a rotating-frame relaxation time of 760 ms.
rugar, with Budakian, Mamin, and Chui single
spin IBM Almaden
Kriewall200412 200412 Thesis
Dissertation, presents heterodyne control as a technique for
computationally efficient digital feedback control of a high-frequency,
narrowband micromechanical oscillator. In this technique, isolated and
synchronized hardware downconversion and upconversion components are used
in conjunction with digital signal processing (DSP) to control the
oscillator. Heterodyne control offers several advantages over
conventional control for high-frequency systems including reduced
computational effort, reduction of noise outside the passband, and
generation of lock-in amplifier signals useful for online diagnostics,
system identification and adaptive control. sidles
signal processing
University of Washington
Barbic200501
200501 Nano Letters, vol 5, no 1, p187-190,
Composite Nanowire-Based Probes for Magnetic Resonance Force Microscopy,
We present a nanowire-based methodology for the fabrication of ultrahigh
sensitivity and resolution probes for atomic resolution magnetic resonance
force microscopy (MRFM). The fabrication technique combines
electrochemical deposition of multifunctional metals into nanoporous
polycarbonate membranes and chemically selective electroless deposition of
optical nanoreflector onto the nanowire. The completed composite nanowire
structure contains all the required elements for an ultrahigh sensitivity
and resolution MRFM sensor with (a) a magnetic nanowire segment providing
atomic resolution magnetic field imaging gradients as well as large force
gradients for high sensitivity, (b) a noble meta enhanced nanowire segment
providing efficient scattering cross-section from a sub wavelength source
for optical readout of nanowire vibration, and (c) a
nonmagnetic/nonplasmonic nanowire segment providing the cantilever
structure for mechanical detection of magnetic resonance.
barbic, with Scherer cantilever
fabrication California State University Long Beach,
Caltech
Budakian200501 200501
Science, Reports, vol 307, Creating Order from Random
Fluctuations in Small Spin Ensembles, We demonstrate the ability to create
spin order by using a magnetic resonance force microscope to harness the
naturally occurring statistical fluctuations in small ensembles of
electron spins. In one method, we hyperpolarized the spin system by
selectively capturing the transient spin order created by the statistical
fluctuations. In a second method, we took a more active approach and
rectified the spin fluctuations by applying real-time feedback to the
entire spin ensemble. The created spin order can be stored in the
laboratory frame for a period on the order of the longitudinal relaxation
time of 30 seconds and then read out. budakian, with
Mamin, Chui, and Rugar spin
relaxation IBM Almaden
Chernobrod200501 200501 J Appl Phys, vol 97,
Spin microscope based on optically detected magnetic resonance, We propose
a scanning magnetic microscope which has a photoluminescence nanoprobe
implanted in the tip of an AFM or STM, or NSOM, and exhibits optically
detected magnetic resonance (ODMR). The proposed spin microscope has
nanoscale lateral resolution and the single spin sensitivity for AFM and
STM. - with berman berman optics
models LANL
Mancini200502 200502 Phys Rev B, vol
71, Quantum dynamics in single spin measurements, We study the quantum
dynamics of a model for the single-spin measurement in magnetic-resonance
force microscopy. We consider an oscillating driven cantilever coupled
with the magnetic moment of the sample. Then, the cantilever is damped
through an external bath and its readout is provided by a radiation field.
Conditions for reliable measurements will be discussed.
moya-cessa, with Vitali spin
measurement Universita di Camerino, INAOE, ICTP
Barbic200503 200503
Nano Letters, Vol 5, No 4, 787-792, Nanomagnetic planar magnetic
resonance microscopy lens barbic, with Scherer
resonant imaging California
State University Long Beach, Caltech
Bargatin200503 200503 Appl Phys Lett, vol
86, 133109, Sensitive detection of nanomechanical motion using
piezoresistive signal downmixing roukes, with Myers,
Arlett, and Gudlewski oscillator
models Caltech
Hero200505
200505 Proc EUSIPCO, Vienna, Two State
Markov Modelling and Detection of Single Electron Spin Signals
hero, with Ting, and Fessler rts
signal University of Michigan
Volodin200505 200505 Rev Sci
Instrum, Piezoresistive mechanical detector for magnetic resonance force
microscopy Volodin, with Brutnix, Brems, and van
Haesendonck mrfm piezoresistive
Katholieke Universiteit
Mamin200507 200507 Phys Rev B, 72, Magnetic
resonance force microscopy of nuclear spins: detection and manipulation of
statistical polarization, We have detected and manipulated the naturally
occurring N statistical polarization in nuclear spin ensembles using
magnetic resonance force microscopy. Using protocols previously developed
for detecting single electron spins, we have measured signals from
ensembles of nuclear spins in a volume of roughly 150 nm^3 with a
sensitivity of roughly 2000 net spins in a 2.5 h averaging window. Three
systems have been studied, 19F nuclei in CaF2, and 1H nuclei protons in
both polymethylmethacrylate and collagen, a naturally occurring protein.
By detecting the statistical polarization, we not only can work with
relatively small ensembles, but we eliminate any need to wait a
longitudinal relaxation time T1 to polarize the spins. We have also made
use of the fact that the statistical polarization, which can be considered
a form o spin noise, has a finite correlation time. A method similar to
one previously proposed by Carlson et al. Bull. Am. Phys. Soc. 44, 541
1999 has been used to suppress the effect of the statistical uncertainty
and extract meaningful information from time-averaged measurements. By
implementing this method, we have successfully made nutation and
transverse spin relaxation time measurements in CaF2 at low temperatures.
rugar, with Budakian, Chui nuclear
polarization IBM Almaden
Berman200510 200510
ArXiv:Cond-mat, The theory of frequency shifts as a function of the spin
location, using the oscillating cantilever-driven adiabatic reversals
technique berman, with borgonovi and tsifrinovich
oscar frequency LANL,
Universita' Cattolica, Polytechnic University
Chabot200510 200510 J Microelectromechanical
Systems, vol 14, no 5, In this paper, we report on the design,
fabrication, and implementation of ultrasensitive micromechanical
oscillators. Our ultrathin single-crystal silicon cantilevers with
integrated magnetic structures are the first of their kind: They are
fabricated using a novel high-yield process in which magnetic film
patterning and deposition are combined with cantilever fabrication. These
novel devices have been developed for use as cantilever magnetometers and
as force sensors in nuclear magnetic resonance force microscopy (MRFM).
These two applications have achieved nanometer-scale resolution using the
cantilevers described in this work. Current magnetic moment sensitivity
achieved for the devices, when used as magnetometers, is at room
temperature, which is more than a 1000-fold improvement in sensitivity,
compared to conventional magnetometers. Current room temperature force
sensitivity of MRFM cantilevers is, which is comparable to the room
temper- ature sensitivities of similar devices of its type. Finite element
modeling was used to improve design parameters, ensure that the devices
meet experimental demands, and correlate mode shape with observed results.
The photolithographic fabrication process was optimized, yielding an
average of and alignment better than 1 . Postfabrication-focused ion-beam
milling was used to further pattern the integrated magnetic structures
when nanometer scale dimensions were required. moreland,
with liu cantilever fabrication
University of San Diego, NIST, University of Nebraska,
University of Texas
Degen200512
200512 Thesis Dissertation, Magnetic Resonance Force
Microscopy: NMR Spectroscopy on the Micro- and Nanoscale
meier mrfm nmr
Swiss Federal Institute of Technology
Moresi200512 200512 Thesis Dissertation,
Magnetic resonance force microscopy: Interaction forces and channels of
energy dissipation meyer mrfm
dissipation University of Basel
Giorgio200601 200601
Nanotechnology, 17, Magnetic damping losses of tipped cantilevvers
meier magnetic tip
ETH, University of Basel
Tsuji200601
200601 J Mag Res, 178, Three dimensional
magnetic resonance imaging by magnetic resonance force microscopy with a
sharp magnetic needle, An electropolished magnetic needle made of Nd2Fe14B
permanent magnet was used for obtaining better spatial resolution than
that achieved in our previous work. We observed the magnetic field
gradient GZ = 80.0 G/um and the field strength B = 1250 G at Z of 8.8 um
from the top of the needle. The use of this needle for three dimensional
magnetic resonance force microscopy at room temperature allowed us to
achieve the voxel resolution to be 0.6 um x 0.6 um x 0.7 um in the
reconstructed image of DPPH phantom. The acquisition time spent for the
whole data collection over 64 x 64 x 16 points, including an iterative
signal average by six times per point, was about 10 days.
yoshinari mri tip
JEOL
Ng200603 200603
IEEE Transactions on Magnetics, vol 42, no 3, Thermomagnetic
Fluctuations and Hysteresis Loops of Magnetic Cantilevers for Magnetic
Resonance Force Microscopy, We have used frequency-shift cantilever
magnetometry to study individual nickel magnets patterned at the end of
ultra-sensitive silicon cantilevers for use in magnetic resonance force
microscopy (MRFM). We present a procedure for inferring a magnet's full
hysteresis curve from the response of cantilever resonance frequency
versus magnetic field. Hysteresis loops and small-angle fluctuations were
determined at 4.2 K with an applied magnetic field up to 6 T for magnets
covering a range of dimensions and aspect ratios. Compared to magnetic
materials with higher anisotropy, we find that nickel is preferable for
MRFM experiments on nuclear spins at high magnetic fields
marohn magnetic noise
Cornell
Rast200603
200603 Nanotechnology, 17, Force microscopy experiments
with ultrasensitive cantilevers rast, with Gerber and
Meyer cantilever experiments
University of Basel, Chonnam National University,
Yongbong-dong, Korea
Bartlett200604
200604 New Journal of Physics, 8, We investigate the
degradation of reference frames (RFs), treated as dynamical quantum
systems, and quantify their longevity as a resource for performing tasks
in quantum information processing. We adopt an operational measure of an
RF's longevity, namely, the number of measurements that can be made
against it with a certain error tolerance. We investigate two distinct
types of RF: a reference direction, realized by a spin-j system, and a
phase reference, realized by an oscillator mode with bounded energy. For
both cases, we show that our measure of longevity increases quadratically
with the size of the reference system and is therefore non-additive. For
instance, the number of measurements for which a directional RF consisting
ofN parallel spins can be put to use scales as N2. Our results quantify
the extent to which microscopic or mesoscopic RFs may be used for
repeated, high-precision measurements, without needing to be reset-a
question that is important for some implementations of quantum computing.
We illustrate our results using the proposed single-spin measurement
scheme of magnetic resonance force microscopy. bartlett,
references Rugar and Sidles spin
reference University of Sydney, Imperial College
London, University of Cambridge, University of Calgary
Kuehn200604 200604 Phys Rev Lett, vol
96, Dielectric fluctuations underlie a wide variety of physical phenomena,
from ion mobility in electrolyte solutions and decoherence in quantum
systems to dynamics in glass-forming materials and on formational changes
in proteins. Here we show that dielectric fluctuations also lead to
noncontact friction. Using high sensitivity, custom fabricated, single
crystal silicon cantilevers we measure energy losses over poly(methyl
methacrylate), poly(vinyl acetate), and polystyrene thin films. A new
theoretical analysis, relating noncontact friction to the dielectric
response of the film, is consistent with our experimental observations.
This work constitutes the first direct, mechanical detection of noncontact
friction due to dielectric fluctuations. marohn
dielectric tip Cornell
Barbic200606 200606
J Mag Res, 181, The methodology for obtaining two- and
three-dimensional magnetic resonance images by using azimuthally symmetric
dipolar magnetic fields from ferromagnetic spheres is described. We
utilize the symmetric property of a geometric sphere in the presence of a
large externally applied magnetic field to demonstrate that a complete
two- or three-dimensional structured rendering of a sample can be obtained
without the motion of the sample relative to the sphere. Sequential
positioning of the integrated sample-sphere system in an external magnetic
field at various angular orientations provides all the required imaging
slices for successful computerized tomographic image reconstruction. The
elimination of the requirement to scan the sample relative to the
ferromagnetic tip in this imaging protocol is a potentially valuable
simplification compared to previous scanning probe magnetic resonance
imaging proposals. barbic, with Scherer
resonance ferromagnetics California
State University Long Beach, Caltech
Chao200606
200606 Rev Sci Inst, 77, The design and
control of a three dimensional piezoceramic tube scanner with an inertial
slider. Inertial sliders are often used to produce coarse relative
positioning for scanning probe microscopes. This article describes the
design, dynamic analysis, and control of a compact four-segment
piezoceramic tube scanner employing an inertial slider. Velocity feedback
control, implemented using two-segment piezoelectric sensing, was used to
suppress undesired vibrations in the tube, and to improve scanner step
uniformity. The control analysis was based on an empirical open-loop
identification of the as-built tube behavior, which was also measured
using the two-segment sensing technique. A reset integrator friction
simulation predicted the overall system performance, and showed good
agreement with experimental results. sidles, with Garbini,
Dougherty, and Chao scanner control
University of Washington
Urban200606
200606
Phys Rev B, 73,
Perturbation of magnetostatic modes observed by ferromagnetic resonance
force microscopy, Magnetostatic modes of yttrium iron garnet YIG films are
investigated by ferromagnetic resonance force microscopy. A thin-film
probe magnet at the tip of a compliant cantilever introduces a local
inhomogeneity in the internal field of the YIG sample. This influences the
shape of the sample's magnetostatic modes, thereby measurably perturbing
the strength of the force coupled to the cantilever. We present a
theoretical model that explains these observations; it shows that the
tip-induced variation of the internal field creates either a local
potential barrier or potential well for the magnetostatic waves. The
data and model together indicate that local magnetic imaging of
ferromagnets is possible, even in the presence of long-range spin
coupling, through the introduction of localized magnetostatic modes
predicted to arise from sufficiently strong tip fields.
hammel, with Roukes, Wigen, and Liou thin film
ferromagnetics Caltech, Ohio State University,
University of Nebraska
Norman200608
200608 Thesis, Design, fabrication and validation of
a DPPH/Polystyrene nanoparticle phantom target for MRFM
sidles DPPH sample
University of Washington
Budakian200609
200609 Appl Phys Lett, 89, Spin manipulation using
fast cantilever phase reversals, The authors show that the phase of a
high-Q cantilever can be reversed abruptly, and they use this capability
to detect spins for magnetic resonance force microscopy. Spins are
manipulated at the cantilever resonant frequency while driving the
cantilever with a wave form that has no Fourier component at this
frequency. This amplitude-based detection protocol is motivated by the
desire to avoid the effects of surface-induced force noise, which can
interfere with frequency-based detection schemes. The technique has been
applied to the detection of E centers and has shown significantly reduced
susceptibility to surface noise, resulting in improved signal-to-noise
ratio. rugar mrfm rf
IBM Almaden
Wang200612
200612 Phys Rev Lett, Magnetic Resonance in
an Atomic Vapor Excited by a Mechanical Resonator, We demonstrate a direct
resonant interaction between the mechanical motion of a mesoscopic
resonator and the spin degrees of freedom of a sample of neutral atoms in
the gas phase. This coupling, mediated by a magnetic particle attached to
the tip of the miniature mechanical resonator, excites a coherent
precession of the atomic spins about a static magnetic field. The novel
coupled atom-resonator system may enable development of low-power,
high-performance sensors, and enhance research efforts connected with the
manipulation of cold atoms, quantum control, and high-resolution
microscopy. moreland resonator
magnetometer NIST, Boulder
Wei200612 200612 Phys Rev Lett,
Probing Tiny Motions of Nanomechanical Resonators: Classical or Quantum
Mechanical?, We propose a spectroscopic approach to probe tiny vibrations
of a nanomechanical resonator (NAMR), which may reveal classical or
quantum behavior depending on the decoherence-inducing environment. Our
proposal is based on the detection of the voltage-fluctuation spectrum in
a superconducting transmission line resonator (TLR), which is indirectly
coupled to the NAMR via a controllable Josephson qubit acting as a quantum
transducer. The classical (quantum mechanical) vibrations of the NAMR
induce symmetric (asymmetric) Stark shifts of the qubit levels, which can
be measured by the voltage fluctuations in the TLR. Thus, the motion of
the NAMR, including if it is quantum mechanical or not, could be probed by
detecting the voltage-fluctuation spectrum of the TLR.
moreland resonator qm
NIST, Boulder
Obukhov200702
200702 J Appl Phys, 101, Real time cantilever signal
frequency determination using digital signal processing, We describe a
digital signal processing method for high precision frequency evaluation
of approximately sinusoidal signals based on a computationally efficient
method. We demonstrate frequency measurement enabling sensitive
measurement of the oscillatory force exerted on a micromechanical
cantilever. We apply this technique to detection of the force signal
arising in a micromechanically detected magnetic resonance force
microscopy electron spin resonance signal. Our frequency detection
measurements agree well with the theoretical noise analysis presented
here, and we find that due to the excellent sensitivity of optical
displacement detection, our sensitivity is limited only by the thermal
displacement noise of the cantilever. hammel
cantilever dsp Ohio State
University
Mamin200704 200704
Nature, Nanotechnology, Magnetic resonance imaging (MRI) is
a powerful imaging technique that typically operates on the scale of
millimetres to micrometres. Conventional MRI is based on the manipulation
of nuclear spins with radio-frequency (RF) fields, and the subsequent
detection of spins with induction-based techniques. An alternative
approach, magnetic resonance force microscopy (MRFM), uses force detection
to overcome the sensitivity limitations of conventional MRI. Here, we show
that the two-dimensional imaging of nuclear spins with MRI can be extended
to a spatial resolution better than 100 nm using MRFM. The imaging of 19F
nuclei in a patterned CaF2 test object was enabled by a detection
sensitivity of roughly 1,200 nuclear spins at a temperature of 600 mK. To
achieve this sensitivity, we developed high-moment magnetic tips that
produced field gradients up to 1.4 x 10^6 Tm^-1, and implemented a
measurement protocol based on force-gradient detection of naturally
occurring spin fluctuations. The resulting detection volume was less than
650 zeptolitres. This is 60,000 times smaller that the previous smallest
volume for nuclear magnetic resonance (NMR) microscopy, and demonstrates
the feasibility of pushing MRI into the nanoscale regime.
rugar nmr resolution
IBM, Stanford University
Poggio200706
200706 Appl Phys Lett, 90, The authors use a
1.0 um wide patterned Cu wire with an integrated nanomagnetic tip to
measure the statistical nuclear polarization of 19F in CaF2 by magnetic
resonance force microscopy. With less than 350 uW of dissipated power, the
authors achieve rf magnetic fields over 4 mT at 115 MHz for a sample
positioned within 100 nm of the ``microwire'' rf source. A 200 nm
diameter FeCo tip integrated onto the wire produces field gradients
greater than 10^5 T/m at the same position. The large rf fields from the
broadband microwire enable long rotating-frame spin lifetimes of up to 15
s at 4 K. rugar wire
tip IBM, Stanford
Poggio200707 200707 Phys Rev Lett, 99,
Feedback cooling of a cantilever's fundamental mode below 5 mK, We cool
the fundamental mechanical mode of an ultrasoft silicon cantilever from a
base temperature of 2.2 K down to 2.9 + 0.3 mK using active optomechanical
feedback. The lowest observed mode temperature is consistent with limits
determined by the properties of the cantilever and by the measurement
noise. For high feedback gain, the driven cantilever motion is found to
suppress or squash the optical interferometer intensity noise below
the shot noise level. rugar cantilever
cooling
Jensen 200708 200708 J Appl Phys, 102,
Magnetic resonance force microscopy (MRFM) and other emerging scanning
probe microscopies entail the detection of attonewton-scale forces.
Requisite force sensitivities are achieved through the use of soft force
microscope cantilevers as high resonant-Q micromechanical oscillators. In
practice, the dynamics of these oscillators are greatly improved by the
application of force feedback control computed in real time by a digital
signal processor. Improvements include increased sensitive
bandwidth, reduced oscillator ring up/down time, and reduced cantilever
thermal vibration amplitude. However, when the cantilever tip and the
sample are in close proximity, electrostatic and Casimir tip-sample force
gradients can significantly alter the cantilever resonance frequency,
foiling fixed-gain narrow-band control schemes. We report an improved,
adaptive control algorithm that uses a Hilbert transform technique to
continuously measure the vibration frequency of the thermally-excited
cantilever and seamlessly adjust the DSP program coefficients. The
closed-loop vibration amplitude is typically 0.05 nm. This adaptive
algorithm enables narrow-band formally-optimal control over a wide range
of resonance frequencies, and preserves the thermally-limited signal to
noise ratio (SNR). sidles cantilever
control University of Washington