Josephson effect in point contacts between two-band superconductors

TL;DR

This paper develops a microscopic theory for the Josephson effect in point contacts between two-band superconductors, analyzing the influence of interband scattering and phase shifts on the critical current, including pi-junction behavior.

Contribution

It introduces a general expression for the Josephson current in two-band superconductors valid at all temperatures, considering interband scattering effects.

Findings

Critical current can be negative, indicating pi-junction behavior.

Interband scattering influences the Josephson current near Tc.

Phase shifts affect the coupling between bands.

Abstract

The microscopic theory of Josephson effect in point contacts between two-band superconductors is developed. The general expression for the Josephson current, which is valid for arbitrary temperatures, is obtained. We considered the dirty superconductors with interband scattering, which produces the coupling of the Josephson currents between different bands. The influence of phase shifts and interband scattering rates in the banks is analyzed near critical temperature Tc. It is shown that for some values of parameters the critical current can be negative, which means the pi-junction behavior.