Josephson currents in point contacts between dirty two-band superconductors

TL;DR

This paper presents a microscopic theory for Josephson currents in point contacts between dirty two-band superconductors, analyzing temperature dependence, interband scattering effects, and applying findings to MgB2.

Contribution

It introduces a general expression for Josephson current in dirty two-band superconductors applicable at all temperatures, including interband scattering effects.

Findings

Derived a universal formula for Josephson current in two-band superconductors.

Analyzed temperature dependence of critical current in MgB2.

Showed interband scattering influences contact characteristics and depends on phase shift.

Abstract

We developed microscopic theory of Josephson effect in point contacts between dirty two-band superconductors. The general expression for the Josephson current, which is valid for arbitrary temperatures, is obtained. This expression was used for calculation of current-phase relations and temperature dependences of critical current with application to MgB2 superconductor. Also we have considered influence on contact characteristics interband scattering effect appeared in case of dirty superconductors. It is shown that the correction to Josephson current due to the interband scattering depends on phase shift in the banks (i.e. s- or s+/- -wave symmetry of order parameters)