Crossed Andreev reflection and spin-resolved non-local electron transport

TL;DR

This paper presents a comprehensive theory of non-local charge transport in disordered ferromagnet-superconductor-ferromagnet structures, highlighting the sensitivity of crossed Andreev reflection to electron spins and magnetic effects.

Contribution

It provides a non-perturbative analysis of non-local conductance in FSF structures, revealing how magnetic effects influence electron interference and conductance.

Findings

CAR is highly sensitive to electron spins.

Magnetic effects can suppress or reverse non-local conductance.

Non-local resistance behaves similarly to non-magnetic cases at higher energies.

Abstract

The phenomenon of crossed Andreev reflection (CAR) is known to play a key role in non-local electron transport across three-terminal normal-superconducting-normal (NSN) devices. Here we review our general theory of non-local charge transport in three-terminal disordered ferromagnet-superconductor-ferromagnet (FSF) structures. 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, degree of disorder, spin-dependent interface transmissions and their polarizations. We demonstrate that magnetic effects have different implications: While strong exchange field suppresses disorder-induced electron interference in ferromagnetic electrodes, spin-sensitive electron scattering at SF interfaces can drive the total non-local conductance negative at sufficiently low energies. At higher energies magnetic effects become less important and the non-local resistance behaves similarly to the non-magnetic case. 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.