Crossed Andreev reflection at spin-active interfaces

TL;DR

This paper develops a non-perturbative theoretical framework for understanding crossed Andreev reflection in three-terminal ballistic NSN devices with spin-active interfaces, revealing its sensitivity to electron spins and diverse conductance properties.

Contribution

It introduces a comprehensive theory of non-local electron transport in NSN devices with spin-active interfaces, accounting for arbitrary voltages, temperatures, and spin polarizations, which was not previously available.

Findings

CAR is highly sensitive to electron spins.

Non-local conductance exhibits a rich variety of properties.

Theory applicable to multi-terminal hybrid structures with various electrodes.

Abstract

With the aid of the quasiclassical Eilenberger formalism we develop a theory of non-local electron transport across three-terminal ballistic normal-superconducting-normal (NSN) devices with spin-active NS interfaces. The phenomenon of crossed Andreev reflection (CAR) is known to play the key role in such transport. We demonstrate that CAR is highly sensitive to electron spins and yields a rich variety of properties of non-local conductance which we describe non-perturbatively at arbitrary voltages, temperature, spin-dependent interface transmissions and their polarizations. Our results can be applied to multi-terminal hybrid structures with normal, ferromagnetic and half-metallic electrodes and can be directly tested in future experiments.