Joseph J. Betouras

Mixed-symmetry superconductivity in two-dimensional Fermi liquids

We consider a two-dimensional (2D) isotropic Fermi liquid with attraction in both {ital s} and {ital d} channels and examine the possibility of a superconducting state with mixed {ital s} and {ital d} symmetry of the gap function. We show that both in the weak-coupling limit and at strong coupling, a mixed {ital s}+{ital id} symmetry state is realized in a certain range of interaction. Phase transitions between the mixed and the pure symmetry states are second order. We also show that there is no stable mixed {ital s}+{ital d} symmetry state at any coupling. {copyright} {ital 1996 The American Physical Society.}

Generic properties of a quasi-one-dimensional classical Wigner crystal

We studied the structural, dynamical properties and melting of a quasi-one-dimensional system of charged particles, interacting through a screened Coulomb potential. The ground-state energy was calculated and, depending on the density and the screening length, the system crystallizes in a number of chains. As a function of the density (or the confining potential), the ground state configurations and the structural transitions between them were analyzed both by analytical and Monte Carlo calculations. The system exhibits a rich phase diagram at zero temperature with continuous and discontinuous structural transitions. We calculated the normal modes of the Wigner crystal and the magnetophonons when an external constant magnetic field B is applied. At finite temperature the melting of the system was studied via Monte Carlo simulations using the modified Lindemann criterion (MLC). The melting temperature as a function of the density was obtained for different screening parameters. Reentrant melting as a function of the density was found as well as evidence of directional dependent melting. The single-chain regime exhibits anomalous melting temperatures according to the MLC and as a check we study the pair-correlation function at different densities and different temperatures, which allowed us to formulate a different melting criterion. Possible connection with recent theoretical and experimental results are discussed and experiments are proposed.

Effects of carrier concentration on the superfluid density of high- T c cuprates

The absolute values and temperature, T, dependence of the in-plane magnetic penetration depth of

Theoretical study of the critical current of YBa2Cu3O7−δ bicrystals with hole-deficient grain boundaries

{\mathrm{La}}_{2\ensuremath{-}x}{\mathrm{Sr}}_{x}{\mathrm{CuO}}_{4}

Multiferroicity Induced by Dislocated Spin-Density Waves

and

Temperature-Dependent Gap Anisotropy in Bi2Sr2CaCu2O8+x as Evidence for a Mixed-Symmetry Ground State

{\mathrm{HgBa}}_{2}{\mathrm{CuO}}_{4+\ensuremath{\delta}}

Ginzburg-Landau theory and effects of pressure on a two-band superconductor: application to MgB 2

have been measured as a function of carrier concentration. We find that the superfluid density

Thermodynamics of a Fermi liquid in a magnetic field

{\ensuremath{\rho}}_{s}

How to test the "quantumness" of a quantum computer?

changes substantially and systematically with doping. The values of

Non-Landau Damping of Magnetic Excitations in Systems with Localized and Itinerant Electrons

{\ensuremath{\rho}}_{s}(0)