Giant nonreciprocity of current-voltage characteristics of noncentrosymmetric supercondctor-normal metal-superconductor junctions

TL;DR

This paper develops a theory explaining the giant nonreciprocal current-voltage behavior in noncentrosymmetric superconductor-normal metal-superconductor junctions, highlighting the role of quasiparticle density of states and phase difference.

Contribution

It introduces a theoretical framework for nonreciprocal I-U characteristics in such junctions, emphasizing the impact of phase difference and quasiparticle relaxation times.

Findings

Nonreciprocal I-U features depend on quasiparticle density of states and phase difference.

Nonreciprocity amplitude scales with inelastic relaxation time, much larger than in normal metals.

Low bias I-U characteristics exhibit additional symmetry under current, voltage, and magnetic field reversal.

Abstract

We develop a theory of nonreciprocal current-voltage (I-U) characteristics in noncentrosymmetric superconductor-normal metal-superconductor junctions. We show that at small voltages the nonreciprocal features of the I-U characteristics can be expressed entirely in terms of the dependence of the nonreciprocal part of the quasiparticle density of states in the normal metal part of the junction on the order parameter phase difference $\chi$ across the junction. The amplitude of the nonreciprocity in this regime is proportional to the inelastic quasiparticle relaxation time $\tau_{in}$, and can be much larger than that in normal materials, where it is proportional to the elastic relaxation time $\tau_{el}$. At low bias the I-U characteristics possess additional symmetry, not present in normal conductors; they remain invariant under simultaneous reversal of current, voltage and the magnetic field.