Supercurrent diode effect and finite momentum superconductivity

TL;DR

This paper explores how certain two-dimensional superconductors exhibit nonreciprocal critical currents and fields due to finite momentum pairing induced by magnetic fields, revealing a supercurrent diode effect.

Contribution

It demonstrates the emergence of finite momentum superconductivity and supercurrent diode effects in 2D materials with antisymmetric spin-orbit coupling under magnetic fields.

Findings

Finite momentum pairing leads to nonreciprocal critical currents.

Supercurrent diode effect observed in specific 2D superconductors.

Polarity-dependent in-plane critical fields are induced by supercurrents.

Abstract

When both inversion and time-reversal symmetries are broken, the critical current of a superconductor can be nonreciprocal. In this work we show that in certain classes of two-dimensional superconductors with antisymmetric spin-orbit coupling, Cooper pairs acquire a finite momentum upon the application of an in-plane magnetic field, and as a result, critical currents in the direction parallel and antiparallel to the Cooper pair momentum become unequal. This supercurrent diode effect is also manifested in the polarity-dependence of in-plane critical fields induced by a supercurrent. These nonreciprocal effects may be found in polar SrTiO$_3$ film, few-layer MoTe$_2$ in the $T_d$ phase, and twisted bilayer graphene in which the valley degrees of freedom plays the role analogous to spin.