Giant Backscattering Peak in Angle-Resolved Andreev Reflection

TL;DR

This paper demonstrates analytically and numerically that disordered normal-metal superconductor junctions exhibit a giant backscattering peak in Andreev reflection, significantly exceeding the normal-state coherent backscattering peak, detectable via ballistic point contacts.

Contribution

It reveals a giant backscattering peak in Andreev reflection at superconductor interfaces, surpassing normal-state peaks, with potential experimental detection methods.

Findings

The angular distribution of Andreev reflection has a narrow, high peak at the incident angle.

The peak exceeds the normal-state coherent backscattering peak by a large factor G/G_0.

The phenomenon can be observed using ballistic point contacts.

Abstract

It is shown analytically and by numerical simulation that the angular distribution of Andreev reflection by a disordered normal-metal -- superconductor junction has a narrow peak at the angle of incidence. The peak is higher than the well-known coherent backscattering peak in the normal state, by a large factor G/G_0 (where G is the conductance of the junction and G_0=2e^2/h). The enhanced backscattering can be detected by means of ballistic point contacts.