16,881 research outputs found
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
AKSZ-BV Formalism and Courant Algebroid-induced Topological Field Theories
We give a detailed exposition of the Alexandrov-Kontsevich-Schwarz-
Zaboronsky superfield formalism using the language of graded manifolds. As a
main illustarting example, to every Courant algebroid structure we associate
canonically a three-dimensional topological sigma-model. Using the AKSZ
formalism, we construct the Batalin-Vilkovisky master action for the model.Comment: 13 pages, based on lectures at Rencontres mathematiques de Glanon
200
Rapid consolidation of powdered materials by induction hot pressing
A rapid hot press system in which the heat is supplied by RF induction to rapidly consolidate thermoelectric materials is described. Use of RF induction heating enables rapid heating and consolidation of powdered materials over a wide temperature range. Such rapid consolidation in nanomaterials is typically performed by spark plasma sintering (SPS) which can be much more expensive. Details of the system design, instrumentation, and performance using a thermoelectric material as an example are reported. The Seebeck coefficient, electrical resistivity, and thermal diffusivity of thermoelectric PbTe material pressed at an optimized temperature and time in this system are shown to agree with material consolidated under typical consolidation parameters
QP-Structures of Degree 3 and 4D Topological Field Theory
A A BV algebra and a QP-structure of degree 3 is formulated. A QP-structure
of degree 3 gives rise to Lie algebroids up to homotopy and its algebraic and
geometric structure is analyzed. A new algebroid is constructed, which derives
a new topological field theory in 4 dimensions by the AKSZ construction.Comment: 17 pages, Some errors and typos have been correcte
Glass Transition of the Monodisperse Gaussian Core Model
We numerically study dynamical properties of the one-component Gaussian Core
Model in the supercooled states. We find that nucleation is suppressed as
density increases. Concomitantly the system exhibits glassy slow dynamics
characterized by the two-step and stretched exponential relaxation of the
density correlation as well as drastic increase of the relaxation time. It is
found that violation of the Stokes-Einstein relation is weaker and the
non-Gaussian parameter is smaller than typical model glass formers, implying
weaker dynamic heterogeneities. Besides, agreement of simulation data with the
prediction of mode-coupling theory is exceptionally good, indicating that the
nature of slow dynamics of this ultra-soft particle fluid is mean-field-like.
This fact may be understood as the consequences of multiple overlaps of the
constituent particles at high densities.Comment: 5 pages, 4 figure
Agterberg, Zheng, and Mukherjee Reply
Reply to Ikeda (arXiv:0712.3341).Comment: To appear in Phys. Rev. Let
Thermodynamics and Structural Properties of the High Density Gaussian Core Model
We numerically study thermodynamic and structural properties of the
one-component Gaussian core model (GCM) at very high densities. The solid-fluid
phase boundary is carefully determined. We find that the density dependence of
both the freezing and melting temperatures obey the asymptotic relation, , , where is the number density, which
is consistent with Stillinger's conjecture. Thermodynamic quantities such as
the energy and pressure and the structural functions such as the static
structure factor are also investigated in the fluid phase for a wide range of
temperature above the phase boundary. We compare the numerical results with the
prediction of the liquid theory with the random phase approximation (RPA). At
high temperatures, the results are in almost perfect agreement with RPA for a
wide range of density, as it has been already shown in the previous studies. In
the low temperature regime close to the phase boundary line, although RPA fails
to describe the structure factors and the radial distribution functions at the
length scales of the interparticle distance, it successfully predicts their
behaviors at shorter length scales. RPA also predicts thermodynamic quantities
such as the energy, pressure, and the temperature at which the thermal
expansion coefficient becomes negative, almost perfectly. Striking ability of
RPA to predict thermodynamic quantities even at high densities and low
temperatures is understood in terms of the decoupling of the length scales
which dictate thermodynamic quantities from the interparticle distance which
dominates the peak structures of the static structure factor due to the
softness of the Gaussian core potential.Comment: 10 pages, 10 figure
Theoretical Description of Resistive Behavior near a Quantum Vortex-Glass Transition
Resistive behaviors at nonzero temperatures (T > 0) reflecting a quantum
vortex-glass (VG) transition (the so-called field-tuned
superconductor-insulator transition at T=0) are studied based on a quantum
Ginzburg-Landau (GL) action for a s-wave pairing case containing microscopic
details. The ordinary dissipative dynamics of the pair-field is assumed on the
basis of a consistency between the fluctuation conductance terms excluded from
GL approach and an observed negative magnetoresistance. It is shown that the VG
contribution, G_{vg}(B=B_{vg}, T \to 0),to 2D fluctuation conductance at the VG
transition field B_{vg} depends on the strength of a repulsive-interaction
between electrons and takes a universal value only in the ordinary dirty limit
neglecting the electron-repulsion. Available resistivity data near B_{vg} are
discussed based on our results, and extensions to the cases of a d-wave pairing
and of 3D systems are briefly commented on.Comment: Explanation of data in strongly disordered case, as well as Fig.2 and
3, was renewed, and comments on recent publications were added. To appear in
J.Phys.Soc. Jp
Topological Field Theories and Geometry of Batalin-Vilkovisky Algebras
The algebraic and geometric structures of deformations are analyzed
concerning topological field theories of Schwarz type by means of the
Batalin-Vilkovisky formalism. Deformations of the Chern-Simons-BF theory in
three dimensions induces the Courant algebroid structure on the target space as
a sigma model. Deformations of BF theories in dimensions are also analyzed.
Two dimensional deformed BF theory induces the Poisson structure and three
dimensional deformed BF theory induces the Courant algebroid structure on the
target space as a sigma model. The deformations of BF theories in
dimensions induce the structures of Batalin-Vilkovisky algebras on the target
space.Comment: 25 page
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