Multiple Andreev reflections in two-dimensional Josephson junctions with broken time-reversal symmetry

TL;DR

This paper develops a model for Josephson junctions with spin-active interlayers, analyzing how Andreev bound states influence the current-voltage characteristics, especially in systems with broken time-reversal symmetry, revealing spectroscopic signatures of ABS properties.

Contribution

It introduces a general theoretical model for Josephson junctions with magnetic or topological materials, highlighting the impact of ABS on $I(V)$ characteristics and their spectroscopic analysis.

Findings

ABS cause asymmetric $I(V)$ peaks for single incident angles.

Angle-resolved $I(V)$$ curves reveal chirality and degeneracy of ABS.

Model predicts how ABS modify peak positions and shapes in $I(V)$.

Abstract

Andreev bound states (ABS) occur in Josephson junctions when the total phase of the Andreev and normal reflections is a multiple of $2\pi$. In ballistic junctions with an applied voltage bias, a quasi-particle undergoes multiple Andreev reflections before entering the leads, resulting in peaks in the current-voltage $I(V)$ curve. Here we present a general model for Josephson junctions with spin-active interlayers i.e., magnetic or topological materials with broken time-reversal symmetry. We investigate how ABS change the peak positions and shape of $I(V)$, which becomes asymmetric for a single incident angle. We show how the angle-resolved $I(V)$ curve becomes a spectroscopic tool for the chirality and degeneracy of ABS.