Lower Critical Field Hc1(T) and Pairing Symmetry Based on Eilenberger Theory

We quantitatively estimate different T-dependences of Hc1 between s wave and d wave pairings by Eilenberger theory. The T-dependences of Hc1(T) show quantitative deviation from those in London theory. We also study differences of Hc1(T) between p+ and p- wave pairing in chiral p wave superconductors. There, Hc1(T) is lower in p- wave pairing, and shows the same T-dependence as in s wave pairing.Comment: 2 pages, 1 figur

NMR relaxation time around a vortex in stripe superconductors

Site-dependent NMR relaxation time $T_1({\bf r})$ is calculated in the vortex state using the Bogoliubov-de Gennes theory, taking account of possible "field-induced stripe'' states in which the magnetism arises locally around a vortex core in d-wave superconductivity. The recently observed huge enhancement $T_1^{-1}({\bf r})$ below $T_c$ at a core site in Tl$_2$Ba$_2$CuO$_6$ is explained. The field-induced stripe picture explains consistently other relevant STM and neutron experiments.Comment: 4 pages, 4 figure

Comment on ``Quasiparticle Spectra around a Single Vortex in a d-wave Superconductor''

In a recent Letter Morita, Kohmoto and Maki analyzed the structure of quasiparticle states near a single vortex in a d-wave superconductor using an approximate version of the Bogoliubov - de Gennes theory. Their principal result is the existence of a bound state within the core region at finite energy with full rotational symmetry, which they assert explains the recent scanning tunneling microscopy results on YBCO single crystals. Here we argue that the approximation used in this work is fundamentally inadequate for the description of a d-wave vortex and that the obtained circular symmetry of the local density of states is an unphysical artifact of this approximation.Comment: 1 page REVTeX, to appear in PR

Magnetization process in a chiral p-wave superconductor with multi-domains

A simulation study for the magnetization process is performed for the multi-domain state in a chiral p-wave superconductor, using the time-dependent Ginzburg-Landau theory. The external field penetrates inside as core-less vortices through the domain wall, forming the vortex sheet structure. We find that, with increasing magnetic fields, the domain walls move so that the unstable domains shrink to vanish. Therefore, the single domain structure is realized at higher fields

Flux flow and pinning of the vortex sheet structure in a two-component superconductor

A simulation study using the time-dependent Ginzburg-Landau theory is performed for the vortex state in two-component superconductors, such as PrOs_4_Sb_12_. We investigate the flux flow and the pinning of the vortex sheet structure. We find domain wall that traps half flux-quantum vortices and moves with the flux flow. In the pinning case, we observe an emitting process of a conventional vortex from the vortex sheet by combining a pair of half flux-quantum vortices.Comment: 4 pages, 4 figures, to appear in Phys. Rev.

The effect of nonmagnetic impurities on the local density of states in s-wave superconductors

We study the effect of nonmagnetic impurities on the local density of states (LDOS) in s-wave superconductors. The quasiclassical equations of superconductivity are solved selfconsistently to show how LDOS evolves with impurity concentration. The spatially averaged zero-energy LDOS is a linear function of magnetic induction in low fields, N(E=0)=cB/H_{c2}, for all impurity concentration. The constant of proportionality "c" depends weakly on the electron mean free path. We present numerical data for differential conductance and spatial profile of zero-energy LDOS which can help in estimating the mean free path through the LDOS measurement.Comment: 7 pages, 7 figures (high quality color figure available on request