Diffuse emission in the presence of inhomogeneous spin-orbit interaction for the purpose of spin filtration

TL;DR

This paper investigates how inhomogeneous spin-orbit interaction at a lateral interface can be used to generate highly spin-polarized electron beams, combining diffusive and ballistic regions for effective spin filtration.

Contribution

It generalizes the diffuse emission technique to include spin-dependent scattering at interfaces, proposing a scheme for a nearly fully spin-polarized electron beam device.

Findings

Diffuse emission effectively produces electrons at small angles suitable for spin filtration.

The proposed scheme can generate two nearly fully spin-polarized electron beams.

The approach combines diffusive and ballistic regions for enhanced spin control.

Abstract

A lateral interface connecting two regions with different strengths of the Bychkov-Rashba spin-orbit interaction can be used as a spin polarizer of electrons in two dimensional semiconductor heterostructures. [Khodas \emph{et al.}, Phys. Rev. Lett. \textbf{92}, 086602 (2004)]. In this paper we consider the case when one of the two regions is ballistic, while the other one is diffusive. We generalize the technique developed for the solution of the problem of the diffuse emission to the case of the spin dependent scattering at the interface, and determine the distribution of electrons emitted from the diffusive region. It is shown that the diffuse emission is an effective way to get electrons propagating at small angles to the interface that are most appropriate for the spin filtration and a subsequent spin manipulation. Finally, a scheme is proposed of a spin filter device, see Fig. 9, that creates two almost fully spin-polarized beams of electrons.