Nonlocal Andreev reflection at high transmissions

TL;DR

This paper investigates non-local electron transport in NSN structures, focusing on crossed Andreev reflection and normal scattering, providing a non-perturbative analysis across various interface transmissions with testable predictions.

Contribution

It offers a non-perturbative evaluation of non-local conductance contributions in NSN structures at arbitrary interface transmissions, highlighting maximum effects at full transmission.

Findings

Maximum non-local conductance at fully transmitting interfaces

Identification of two distinct contributions to non-local conductance

Predictions for experimental testing of non-local effects

Abstract

We analyze non-local effects in electron transport across three-terminal normal-superconducting-normal (NSN) structures. Subgap electrons entering S-electrode from one N-metal may form Cooper pairs with their counterparts penetrating from another N-metal. This phenomenon of crossed Andreev reflection -- combined with normal scattering at SN interfaces -- yields two different contributions to non-local conductance which we evaluate non-perturbatively at arbitrary interface transmissions. Both these contributions reach their maximum values at fully transmitting interfaces and demonstrate interesting features which can be tested in future experiments.