509 research outputs found
The Cauchy problem for the 3-D Vlasov-Poisson system with point charges
In this paper we establish global existence and uniqueness of the solution to
the three-dimensional Vlasov-Poisson system in presence of point charges in
case of repulsive interaction. The present analysis extends an analogeous
two-dimensional result by Caprino and Marchioro [On the plasma-charge model, to
appear in Kinetic and Related Models (2010)].Comment: 28 page
Induction of non-d-wave order-parameter components by currents in d-wave superconductors
It is shown, within the framework of the Ginzburg-Landau theory for a
superconductor with d_{x^2-y^2} symmetry, that the passing of a supercurrent
through the sample results, in general, in the induction of order-parameter
components of distinct symmetry. The induction of s-wave and
d_{xy(x^2-y^2)-wave components are considered in detail. It is shown that in
both cases the order parameter remains gapless; however, the structure of the
lines of nodes and the lobes of the order parameter are modified in distinct
ways, and the magnitudes of these modifications differ in their dependence on
the (a-b plane) current direction. The magnitude of the induced s-wave
component is estimated using the results of the calculations of Ren et al.
[Phys. Rev. Lett. 74, 3680 (1995)], which are based on a microscopic approach.Comment: 15 pages, includes 2 figures. To appear in Phys. Rev.
An upper limit on the evolution of carbon monoxide from Comet Kohoutek
The rate of evolution of CO from Comet Kohoutex is presented. The observations were made approximately two months after perihelion. The rate of evolution of CO at that time was apparently less than that of CH3CN observed before perihelion
Effect of spatial variations of superconducting gap on suppression of the transition temperature by impurities
We calculate correction to the critical temperature of a dirty
superconductor, which results from the local variations of the gap function
near impurity sites. This correction is of the order of T_c/E_F and becomes
important for short-coherence length superconductors. It generally reduces a
pair-breaking effect. In s-wave superconductors small amounts of nonmagnetic
impurities can increase the transition temperature.Comment: 5 pages, ReVTE
Quasiparticle transport and localization in high-T_c superconductors
We present a theory of the effects of impurity scattering in d_{x^2-y^2}
superconductors and their quantum disordered counterparts, based on a
non-linear sigma model formulation. We show the existence, in a
quasi-two-dimensional system, of a novel spin-metal phase with a non-zero spin
diffusion constant at zero temperature. With decreasing inter-layer coupling,
the system undergoes a quantum phase transition (in a new universality class)
to a localized spin-insulator. Experimental implications for spin and thermal
transport in the high-temperature superconductors are discussed.Comment: 4 pages, 1 figur
Josephson tunneling in high- superconductors
This article describes the Josephson tunneling from time-reversal
symmetry-breaking states and compares it with that from time-reversal invariant
states for both twinned and untwinned crystals and for both -axis and
basal-plane currents, in a model for orthorhombic YBCO. A macroscopic
invariance group describing the superconducting state of a twinned crystal is
introduced and shown to provide a useful framework for the discussion of the
results for twinned crystals. In addition, a ring geometry, which allows
-wave and -wave superconductivity in a tetragonal
superconductor to be distinguished on the basis of symmetry arguments only, is
proposed and analyzed. Finally, an appendix gives details of the experimental
Josephson tunneling evidence for a superconducting state of orthorhombic
symmetry in YBCO.Comment: Latex File, 18 pages, 6 Postscript figures, submitted to Phys. Rev.
Infrared Conductivity in Layered -wave Superconductors
We calculate the infrared conductivity of a stack of coupled, two-dimensional
superconducting planes within the Fermi liquid theory of superconductivity. We
include the effects of random scattering processes and show that the presence
of even a small concentration of resonant impurities, in a -wave
superconductor, has an important effect on both the in-plane and -axis
transport properties, which could serve as signatures for -wave pairing.Comment: 18 pages in a RevTex (3.0) file plus 5 postscript figures
(uuencoded). Replaced with minor changes as it will appear in the Physical
Review B {\bf 52} issue 1 Oct. 199
Low Temperature Properties of Anisotropic Superconductors with Kondo Impurities
We present a self-consistent theory of superconductors in the presence of
Kondo impurities, using large- slave-boson methods to treat the impurity
dynamics. The technique is tested on the s-wave case and shown to give good
results compared to other methods for . We calculate low temperature
thermodynamic and transport properties for various superconducting states,
including isotropic s-wave and representative anisotropic model states with
line and point nodes on the Fermi surface.Comment: 21 pages, RevTeX 3.0, 12 figures available upon request, UF preprin
Comments on the d-wave pairing mechanism for cuprate high superconductors: Higher is different?
The question of pairing glue for the cuprate superconductors (SC)is revisited
and its determination through the angle resolved photo-emission spectroscopy
(ARPES) is discussed in detail. There are two schools of thoughts about the
pairing glue question: One argues that superconductivity in the cuprates
emerges out of doping the spin singlet resonating valence bond (RVB) state.
Since singlet pairs are already formed in the RVB state there is no need for
additional boson glue to pair the electrons. The other instead suggests that
the d-wave pairs are mediated by the collective bosons like the conventional
low SC with the alteration that the phonons are replaced by another kind
of bosons ranging from the antiferromagnetic (AF) to loop current fluctuations.
An approach to resolve this dispute is to determine the frequency and momentum
dependences of the diagonal and off-diagonal self-energies directly from
experiments like the McMillan-Rowell procedure for the conventional SC. In that
a simple d-wave BCS theory describes superconducting properties of the cuprates
well, the Eliashberg analysis of well designed high resolution experimental
data will yield the crucial frequency and momentum dependences of the
self-energies. This line of approach using ARPES are discussed in more detail
in this review, and some remaining problems are commented.Comment: Invited review article published in the Journal of Korean Physical
Society; several typos corrected and a few comments and references adde
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