Transverse shift in crossed Andreev reflection

TL;DR

This paper uncovers a transverse spatial shift in crossed Andreev reflection within Weyl semimetals, revealing a new spatial aspect of electron-hole conversion that can be experimentally detected and used to probe CAR.

Contribution

It demonstrates the existence of a transverse shift in CAR, generalizes the effect to systems with spin-orbit coupling, and proposes experimental detection methods.

Findings

Transverse shift in CAR can be sizable and detectable.

The shift depends on spin-orbit coupling and differs from elastic cotunneling.

The effect vanishes when the terminals are identical.

Abstract

Crossed Andreev reflection (CAR) is an intriguing effect that occurs in a normal-superconductor-normal junction. In CAR, an incoming electron from one terminal is coherently scattered as an outgoing hole into the other terminal. Here, we reveal that there exists a transverse spatial shift in CAR, i.e., the plane of CAR for the outgoing hole may have a sizable transverse shift from the plane of incidence for the incoming electron. We explicitly demonstrate the effect in a model system based on Weyl semimetals. We further show that the effect is quite general and exists when the terminals have sizable spin-orbit coupling. In addition, we find that the corresponding shift in the elastic cotunneling process shows different behaviors, and it vanishes when the two terminals are identical. Based on these findings, we suggest possible experimental setups for detecting the effect, which may also offer an alternative method for probing CAR.