Superconducting diode effect in diffusive superconductors and Josephson junctions with Rashba spin-orbit coupling

TL;DR

This paper investigates the superconducting diode effect in diffusive superconductors and Josephson junctions with Rashba spin-orbit coupling, revealing how disorder, magnetic field, and junction properties influence the effect.

Contribution

It provides a theoretical analysis of the SDE in diffusive structures, highlighting differences from clean systems and the impact of junction length and magnetic field.

Findings

SDE increases monotonically with magnetic field and decreasing temperature in diffusive superconductors.

SDE dramatically increases and changes sign near the $0- ext{} extpi$ transition in Josephson junctions.

SDE is suppressed in narrow junctions, emphasizing geometry's role.

Abstract

We characterize the superconducting diode effect (SDE) in two-dimensional diffusive structures with Rashba spin-orbit coupling using the quasiclassical formalism. We consider both homogeneous superconductors and Josephson junctions. In the first case, the diode effect monotonically increases as the magnetic field is increased and the temperature is reduced, in contrast to the non-monotonic behavior found in clean structures. In Josephson junctions, SDE dramatically increases and changes its sign close to the $0-\pi$ transition of the junction, which occurs at specific junction lengths and strengths of the magnetic field. We show that the SDE is strongly suppressed in narrow junctions. Our results are relevant for understanding recent experiments that measure SDE in mesoscopic nanostructures, where significant disorder is unavoidable.