Extracting current-induced spins: spin boundary conditions at narrow Hall contacts

TL;DR

This paper investigates how to extract current-induced spins in a 2D electron gas with spin-orbit interaction using narrow Hall contacts, establishing boundary conditions and demonstrating detection feasibility.

Contribution

It introduces boundary conditions for spin accumulation at narrow contacts between spin-orbit coupled and normal 2DEG regions, enabling spin extraction and detection.

Findings

Spin accumulation can diffuse into normal regions through finite contacts.

Narrow impedance-matched contacts allow direct measurement of bulk spin accumulation.

Spin accumulation in the normal region relates to the bulk R2DEG spin accumulation by a geometry-dependent factor.

Abstract

We consider the possibility to extract spins that are generated by an electric current in a two-dimensional electron gas with Rashba-Dresselhaus spin-orbit interaction (R2DEG) in the Hall geometry. To this end, we discuss boundary conditions for the spin accumulations between a spin-orbit coupled region and contact without spin-orbit coupling, i.e. a normal two-dimensional electron gas (2DEG). We demonstrate that in contrast to contacts that extend along the whole sample, a spin accumulation can diffuse into the normal region through finite contacts and detected by e.g. ferromagnets. For an impedance-matched narrow contact the spin accumulation in the 2DEG is equal to the current induced spin accumulation in the bulk of R2DEG up to a geometry-dependent numerical factor.