Josephson effect in point contacts between ''f-wave'' superconductors

TL;DR

This paper theoretically analyzes the Josephson effect in point contacts between triplet ''f-wave'' superconductors, highlighting how crystal misorientation influences current-phase relations and can reveal the order parameter symmetry.

Contribution

It introduces models for the order parameter in UPt_{3} and Sr_{2}RuO_{4} superconductors and predicts how misorientation affects Josephson currents and spontaneous surface currents.

Findings

Different order parameter models lead to distinct current-phase dependences.

Misorientation can induce spontaneous surface currents.

Zero Josephson current states can have a spontaneous phase difference.

Abstract

A stationary Josephson effect in point contacts between triplet superconductors is analyzed theoretically for most probable models of the order parameter in UPt_{3} and Sr_{2}RuO_{4}. The consequence of misorientation of crystals in superconducting banks on this effect is considered. We show that different models for the order parameter lead to quite different current-phase dependences. For certain angles of misorientation a boundary between superconductors can generate the parallel to surface spontaneous current. In a number of cases the state with a zero Josephson current and minimum of the free energy corresponds to a spontaneous phase difference. This phase difference depends on the misorientation angle and may possess any value. We conclude that experimental investigations of the current-phase dependences of small junctions can be used for determination of the order parameter symmetry in the mentioned above superconductors.