Nonlinear transverse magnetic moment in anisotropic superconductors

TL;DR

This paper investigates the nonlinear transverse magnetic moment in anisotropic superconductors with d-wave pairing, providing numerical solutions that could help identify the order parameter symmetry in high-temperature superconductors.

Contribution

It offers a detailed numerical analysis of the nonlinear magnetic response in finite anisotropic superconductors, including shape and current effects, to probe the pairing symmetry.

Findings

The nonlinear transverse magnetic moment is sensitive to d-wave pairing symmetry.

Numerical solutions include effects of shape, return currents, and penetration depth anisotropy.

Measurement of this magnetic moment can distinguish between d-wave and s-wave pairing.

Abstract

We consider the nonlinear transverse magnetic moment that arises in the Meissner state of superconductors with 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 superconducting materials. Return currents, shape effects and the anisotropy of the penetration depth are all included. We numerically solve the nonlinear Maxwell-London equations for a finite system. The effect, which is a probe of the order parameter symmetry in the bulk of the sample, should be readily measurable if pairing is in a d-wave state. Failure to observe it would set a lower bound to the s-wave component.