50 research outputs found
Localized ferromagnetic resonance force microscopy in permalloy-cobalt films
We report Ferromagnetic Resonance Force Microscopy (FMRFM) experiments on a
justaposed continuous films of permalloy and cobalt. Our studies demonstrate
the capability of FMRFM to perform local spectroscopy of different
ferromagnetic materials. Theoretical analysis of the uniform resonance mode
near the edge of the film agrees quantitatively with experimental data. Our
experiments demonstrate the micron scale lateral resolution in determining
local magnetic properties in continuous ferromagnetic samples.Comment: 7 pages, 3 figure
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 (MRFM). We performed MRFM measurements on a well
characterized diphenyl-picrylhydrazyl (DPPH) film and mapped the 3D field
profile produced by a Nd2Fe14B probe tip. Using our technique field profiles of
arbitrarily shaped probe magnets can be imaged.Comment: 10 pages, 5 figure
Direct measurements of the penetration depth in a superconducting film using magnetic force microscopy
We report the local measurements of the magnetic penetration depth
in a superconducting Nb film using magnetic force microscopy (MFM). We
developed a method for quantitative extraction of the penetration depth from
single-parameter simultaneous fits to the lateral and height profiles of the
MFM signal, and demonstrate that the obtained value is in excellent agreement
with that obtained from the bulk magnetization measurements.Comment: 3 pages, 4 figures, submitted to APL on 08/18/0
Ferromagnetic resonance force microscopy on a thin permalloy film
Ferromagnetic Resonance Force Microscopy (FMRFM) offers a means of performing
local ferromagnetic resonance. We have studied the evolution of the FMRFM force
spectra in a continuous 50 nm thick permalloy film as a function of probe-film
distance and performed numerical simulations of the intensity of the FMRFM
probe-film interaction force, accounting for the presence of the localized
strongly nonuniform magnetic field of the FMRFM probe magnet. Excellent
agreement between the experimental data and the simulation results provides
insight into the mechanism of FMR mode excitation in an FMRFM experiment.Comment: 9 pages, 2 figure
Artifact mitigation of ptychography integrated with on-the-fly scanning probe microscopy
We report our experiences with conducting ptychography simultaneously with the X-ray fluorescence
measurement using the on-the-fly mode for efficient multi-modality imaging. We demonstrate
that the periodic artifact inherent to the raster scan pattern can be mitigated using a
sufficiently fine scan step size to provide an overlap ratio of >70%. This allows us to obtain transmitted
phase contrast images with enhanced spatial resolution from ptychography while maintaining
the fluorescence imaging with continuous-motion scans on pixelated grids. This capability
will greatly improve the competence and throughput of scanning probe X-ray microscopy
Large magnetic penetration depth and thermal fluctuations in a Ca(PtAs)[(FePt)As] (x=0.097) single crystal
We have measured the temperature dependence of the absolute value of the
magnetic penetration depth in a
Ca(PtAs)[(FePt)As] (x=0.097)
single crystal using a low-temperature magnetic force microscope (MFM). We
obtain (0)1000 nm via extrapolating the data to .
This large and pronounced anisotropy in this system are responsible
for large thermal fluctuations and the presence of a liquid vortex phase in
this low-temperature superconductor with critical temperature of 11 K,
consistent with the interpretation of the electrical transport data. The
superconducting parameters obtained from and coherence length
place this compound in the extreme type \MakeUppercase{\romannumeral 2} regime.
Meissner responses (via MFM) at different locations across the sample are
similar to each other, indicating good homogeneity of the superconducting state
on a sub-micron scale
Random anisotropy disorder in superfluid 3He-A in aerogel
The anisotropic superfluid 3He-A in aerogel provides an interesting example
of a system with continuous symmetry in the presence of random anisotropy
disorder. Recent NMR experiments allow us to discuss two regimes of the
orientational disorder, which have different NMR properties. One of them, the
(s)-state, is identified as the pure Larkin-Imry-Ma state. The structure of
another state, the (f)-state, is not very clear: probably it is the
Larkin-Imry-Ma state contaminated by the network of the topological defects
pinned by aerogel.Comment: JETP Lett. style, 6 pages, no figures, discussion extended,
references added, version to be published in JETP Letter
Modification of the 3He Phase Diagram by Anisotropic Disorder
Motivated by the recent prediction that uniaxially compressed aerogel can
stabilize the anisotropic A phase over the isotropic B phase, we measure the
pressure dependent superfluid fraction of 3He entrained in 10% axially
compressed, 98% porous aerogel. We observe that a broad region of the
temperature-pressure phase diagram is occupied by the metastable A phase. The
reappearance of the A phase on warming from the B phase, before superfluidity
is extinguished at Tc, is in contrast to its absence in uncompressed aerogel.
The phase diagram is modified from that of pure 3He, with the disappearance of
the polycritical point (PCP) and the appearance of a region of A phase
extending below the PCP of bulk 3He, even in zero applied magnetic field. The
expected alignment of the A phase texture by compression is not observed.Comment: 4 pages, 4 figures. Submitted for review to PR