9,336 research outputs found
High field superconducting phase diagrams including Fulde-Ferrell-Larkin-Ovchinnikov vortex states
Motivated by a striking observation of a Fulde-Ferell-Larkin-Ovchinnikov
(FFLO) vortex state in the heavy fermion material CeCoIn5 in fields {\it
perpendicular} to the superconducting planes (),
superconducting phase diagrams including an FFLO state of quasi two-dimensional
(Q2D) superconductors are systematically studied. In the clean {\it limit}, the
high field superconducting state in the low temperature limit should be not the
FFLO state modulating along , appeared in CeCoIn5 in both and , but a different vortex state with a
modulation, induced by the paramagnetism, perpendicular to the field. It is
found that the presence of weak impurities is the origin of the absence in
CeCoIn5 of the latter state and leads to the phase
diagram, as seen in CeCoIn5, {\it apparently} different in character from that
in .Comment: A reference was updated. To appear in Phys. Rev.
Evidence for realignment of the charge density wave state in ErTe and TmTe under uniaxial stress via elastocaloric and elastoresistivity measurements
We report the evolution of a charge density wave (CDW) state in the quasi-2D
rare-earth tritellurides (Te for =Er,Tm) as a function of in-plane
uniaxial stress. Measurements of the elastocaloric effect, resistivity, and
elastoresistivity allow us to demonstrate the importance of in-plane
antisymmetric strain on the CDW and to establish a phase diagram. We show that
modest tensile stress parallel to the in-plane -axis can reversibly switch
the direction of the ordering wavevector between the two in-plane directions.
This work establishes Te as a promising model system for the study of
strain-CDW interactions in a quasi-2D square lattice.Comment: 18 pages, 12 figure
Josephson Vortex States in Intermediate Fields
Motivated by recent resistance data in high superconductors in fields
{\it parallel} to the CuO layers, we address two issues on the Josephson-vortex
phase diagram, the appearances of structural transitions on the observed first
order transition (FOT) curve in intermediate fields and of a lower critical
point of the FOT line. It is found that some rotated pinned solids are more
stable than the ordinary rhombic pinned solids with vacant interlayer spacings
and that, due to the vertical portion in higher fields of the FOT line, the FOT
tends to be destroyed by creating a lower critical point.Comment: 12 pages, 3 figures. To appear in J.Phys.Soc.Jpn. 71, No.2 (February,
2002
An Alternative Topological Field Theory of Generalized Complex Geometry
We propose a new topological field theory on generalized complex geometry in
two dimension using AKSZ formulation. Zucchini's model is model in the case
that the generalized complex structuredepends on only a symplectic structure.
Our new model is model in the case that the generalized complex structure
depends on only a complex structure.Comment: 29 pages, typos and references correcte
Uniaxial-Pressure induced Ferromagnetism of Enhanced Paramagnetic Sr3Ru2O7
We report a uniaxial pressure-dependence of magnetism in layered perovskite
strontium ruthenate Sr3Ru2O7. By applying a relatively small uniaxial pressure,
greater than 0.1 GPa normal to the RuO2 layer, ferromagnetic ordering manifests
below 80 K from the enhanced-paramagnet. Magnetization at 1 kOe and 2 K becomes
100 times larger than that under ambient condition. Uniaxial pressure
dependence of Curie temperature T_C suggests the first order magnetic
transition. Origin of this uniaxial-pressure induced ferromagnetism is
discussed in terms of the rotation of RuO6 octahedra within the RuO2 plane.Comment: 8 pages, 3 figures. to be published in Journal of the Physical
Society of Japan, vol.73, No.5 (2004
Spin-charge-lattice coupling near the metal-insulator transition in Ca3Ru2O7
We report x-ray scattering studies of the c-axis lattice parameter in
Ca3Ru2O7 as a function of temperature and magnetic field. These structural
studies complement published transport and magnetization data, and therefore
elucidate the spin-charge-lattice coupling near the metal-insulator transition.
Strong anisotropy of the structural change for field applied along orthogonal
in-plane directions is observed. Competition between a spin-polarized phase
that does not couple to the lattice, and an antiferromagnetic metallic phase,
which does, gives rise to rich behavior for B b.Comment: 6 pages, 4 figures, to appear in Phys. Rev.
Thermal fluctuations and disorder effects in vortex lattices
We calculate using loop expansion the effect of fluctuations on the structure
function and magnetization of the vortex lattice and compare it with existing
MC results. In addition to renormalization of the height of the Bragg peaks of
the structure function, there appears a characteristic saddle shape ''halos''
around the peaks. The effect of disorder on magnetization is also calculated.
All the infrared divergencies related to soft shear cancel.Comment: 10 pages, revtex file, one figur
Metamagnetism and critical fluctuations in high quality single crystals of the bilayer ruthenate Sr3Ru2O7
We report the results of low temperature transport, specific heat and
magnetisation measurements on high quality single crystals of the bilayer
perovskite Sr3Ru2O7, which is a close relative of the unconventional
superconductor Sr2RuO4. Metamagnetism is observed, and transport and
thermodynamic evidence for associated critical fluctuations is presented. These
relatively unusual fluctuations might be pictured as variations in the Fermi
surface topography itself. No equivalent behaviour has been observed in the
metallic state of Sr2RuO4.Comment: 4 pages, 4 figures, Revtex 3.
Influence of Noise on Force Measurements
We demonstrate how the ineluctable presence of thermal noise alters the
measurement of forces acting on microscopic and nanoscopic objects. We quantify
this effect exemplarily for a Brownian particle near a wall subjected to
gravitational and electrostatic forces. Our results demonstrate that the force
measurement process is prone to artifacts if the noise is not correctly taken
into account.Comment: 4 Pages, 4 Figures, Accepte
Microscopic Study of Quantum Vortex-Glass Transition Field in Two-Dimensional Superconductors
The position of a field-tuned superconductor-insulator quantum transition
occuring in disordered thin films is examined within the mean field
approximation. Our calculation shows that the microscopic disorder-induced
reduction of the quantum transition point found experimentally cannot be
explained if the interplay between the disorder and an electron-electron
repulsive interaction is ignored. This work is presented as a microscopic basis
of an explanation (cond-mat/0105122) of resistive phenomena near the transition
field.Comment: 16 pages, 5 figures. To appear in J.Phys.Soc.Jp
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