178 research outputs found
Field- and pressure-induced phases in SrRuO: A spectroscopic investigation
We have investigated the magnetic-field- and pressure-induced structural and
magnetic phases of the triple-layer ruthenate - SrRuO.
Magnetic-field-induced changes in the phonon spectra reveal dramatic
spin-reorientation transitions and strong magneto-elastic coupling in this
material. Additionally, pressure-dependent Raman measurements at different
temperatures reveal an anomalous negative Gruneisen-parameter associated with
the B mode ( 380 cm) at low temperatures (T 75K), which
can be explained consistently with the field dependent Raman data.Comment: 5 pages, 4 figures final version published in PRL 96, 067004 (2006
Raman scattering studies of temperature- and field-induced melting of charge order in (La,Pr,Ca)MnO
We present Raman scattering studies of the structural and magnetic phases
that accompany temperature- and field-dependent melting of charge- and
orbital-order (COO) in La0.5Ca0.5MnO3 and La0.25Pr0.375Ca0.375MnO3. Our results
show that thermal and field-induced COO melting in La0.5Ca0.5MnO3 exhibits
three stages in a heterogeneous melting process associated with a structural
change: a long-range, strongly JT distorted/COO regime; a coexistence regime;
and weakly JT distorted/PM or FM phase. We provide a complete structural phase
diagram of La0.5Ca0.5MnO3 for the temperature and field ranges 6<=T<=170 K and
0<=H<=9 T. We also investigate thermal and field-induced melting in
La0.25Pr0.375Ca0.375MnO3 to elucidate the role of disorder in melting of COO.
We find that while thermal melting of COO in La0.25Pr0.375Ca0.375MnO3 is quite
similar to that in La0.5Ca0.5MnO3, the field-induced transition from the COO
phase to the weakly JT-distorted/FM phase in La0.25Pr0.375Ca0.375MnO3 is very
abrupt, and occurs at significantly lower fields (H~2 T at T~0 K) than in
La0.5Ca0.5MnO3 (H~30 T at T=0 K). Moreover, the critical field H_c increases
with increasing temperature in La0.25Pr0.375Ca0.375MnO3 in contrast to
La0.5Ca0.5MnO3. To explain these differences, we propose that field-induced
melting of COO in La0.25Pr0.375Ca0.375MnO3 is best described as the
field-induced percolation of FM domains, and we suggest that Griffiths phase
physics may be an appropriate theoretical model for describing the unusual
temperature- and field- dependent transitions observed in
La0.25Pr0.375Ca0.375MnO3.Comment: 14 pages, 8 figures, to be published in PR
Gapped Excitations in the High-Pressure Antiferromagnetic Phase of URuSi
We report a neutron scattering study of the magnetic excitation spectrum in
each of the three temperature and pressure driven phases of URuSi. We
find qualitatively similar excitations throughout the (H0L) scattering plane in
the hidden order and large moment phases, with no changes in the
-widths of the excitations at the = (1.407,0,0) and =
(1,0,0) points, within our experimental resolution. There is, however, an
increase in the gap at the point from 4.2(2) meV to 5.5(3) meV,
consistent with other indicators of enhanced antiferromagnetism under pressure.Comment: 5 pages, 3 figures, 1 tabl
Relative Pose from Deep Learned Depth and a Single Affine Correspondence
We propose a new approach for combining deep-learned non-metric monocular
depth with affine correspondences (ACs) to estimate the relative pose of two
calibrated cameras from a single correspondence. Considering the depth
information and affine features, two new constraints on the camera pose are
derived. The proposed solver is usable within 1-point RANSAC approaches. Thus,
the processing time of the robust estimation is linear in the number of
correspondences and, therefore, orders of magnitude faster than by using
traditional approaches. The proposed 1AC+D solver is tested both on synthetic
data and on 110395 publicly available real image pairs where we used an
off-the-shelf monocular depth network to provide up-to-scale depth per pixel.
The proposed 1AC+D leads to similar accuracy as traditional approaches while
being significantly faster. When solving large-scale problems, e.g., pose-graph
initialization for Structure-from-Motion (SfM) pipelines, the overhead of
obtaining ACs and monocular depth is negligible compared to the speed-up gained
in the pairwise geometric verification, i.e., relative pose estimation. This is
demonstrated on scenes from the 1DSfM dataset using a state-of-the-art global
SfM algorithm. Source code: https://github.com/eivan/one-ac-pos
Radio Astronomy
Contains reports on four research projects.Joint Services Electronics Program (Contract DAAB07-71-C-0300)California Institute of Technology (Contract 952568)National Aeronautics and Space Administration (Contract NAS1-10693)National Science Foundation (Grant GP-21348A#2
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