The Nonlinear Meissner Effect in Unconventional Superconductors

Author(s): D. Xu, S.-K. Yip and J. A. Sauls
Comments: 30 pages with 16 figures
Physical Review B, 51, 16233 (1995) [DOI]
We examine the long-wavelength current response in anisotropic superconductors and show how the field-dependence of the Meissner penetration length can be used to detect the structure of the order parameter. Nodes in the excitation gap lead to a nonlinear current-velocity constitutive equation at low temperatures which is distinct for each symmetry class of the order parameter. The effective Meissner penetration length is linear in H and exhibits a characteristic anisotropy for fields in the ab-plane that is determined by the positions of the nodes in momentum space. The nonlinear current-velocity relation also leads to an intrinsic magnetic torque for in-plane fields that are not parallel to a nodal or antinodal direction. The torque scales as H3 for T -> 0 and has a characteristic angular dependence. We analyze the effects of thermal excitations, impurity scattering and geometry on the current response of a dx2-y2superconductor, and discuss our results in light of recent measurements of the low-temperature penetration length and in-plane magnetization of single-crystals of YBa2Cu3O7-y and LuBa2Cu3O7-y.

Eprint: [arXiv] [PDF]

Index Return to index