Nonlinear transverse magnetic moment in anisotropic superconductors

[摘要] We consider the nonlinear transverse magnetic moment that arises in the Meissner state of superconductors with a strongly anisotropic order parameter. We compute this magnetic moment as a function of applied field and geometry, assuming d-wave pairing, for realistic samples, finite in all three dimensions, of high-temperature superconducing materials. Return currents, shape effects, and the anisotropy of the penetration depth tensor are all included. We numerically solve the nonlinear Maxwell-London equations for a finite system. Results are discussed in terms of the relevant parameters. The effects, which is a probe of the order parameter symmetry in the bulk, not just the surface, of the sample should be readily measurable if pairing is a d-wave state. Failure to observe it would set a low bound to the s-wave component.

[关键词] PENETRATION DEPTH;UNCONVENTIONAL SUPERCONDUCTORS;IMPURITY SCATTERING;DEPENDENCE;SYMMETRY