Nonlinear current response of one- and two-band superconductors

TL;DR

This paper investigates the nonlinear electrical response of single- and two-band superconductors, considering factors like anisotropy, impurities, and strong coupling, with specific insights into MgB2 based on microscopic parameters.

Contribution

It provides a comprehensive analysis of nonlinear current responses in superconductors, including effects of anisotropy and impurities, and applies findings to MgB2 using band theory data.

Findings

Nonlinear current response varies with dimensionality and impurity levels.

Strong electron-phonon coupling influences nonlinear behavior.

Results specific to MgB2 align with microscopic band theory parameters.

Abstract

We have calculated the nonlinear current of a number of single band s-wave electron-phonon superconductors. Among issues considered were those of dimensionality, strong electron-phonon coupling, impurities, and comparison with BCS. For the case of two bands, particular attention is paid to the role of anisotropy, the integration effects of the off-diagonal electron-phonon interaction, as well as inter- and intraband impurities. For the specific case of MgB2, we present results based on the known microscopic parameters of band theory.