Spin Injection and Detection in Magnetic Nanostructures

TL;DR

This paper provides a theoretical analysis of spin transport in magnetic nanostructures, deriving a general expression for spin signals, and explores the enhancement of spin accumulation in superconducting and semiconductor devices.

Contribution

It introduces a comprehensive theoretical framework for spin injection and detection, including the effects of superconducting gaps on spin signals.

Findings

Spin accumulation signals are enhanced in superconductors due to the gap.

The derived expression applies across metallic and tunneling regimes.

Spin signals are also expected to be enhanced in semiconductors.

Abstract

We study theoretically the spin transport in a nonmagnetic metal connected to ferromagnetic injector and detector electrodes. We derive a general expression for the spin accumulation signal which covers from the metallic to the tunneling regime. This enables us to discuss recent controversy on spin injection and detection experiments. Extending the result to a superconducting device, we find that the spin accumulation signal is strongly enhanced by opening of the superconducting gap since a gapped superconductor is a low carrier system for spin transport but not for charge. The enhancement is also expected in semiconductor devices.