Mach-Zehnder Interferometric device for spin filtering in a GaAs/AlGaAs electron gas

TL;DR

This paper proposes a theoretical spin filtering device based on quantum interference in a GaAs/AlGaAs electron gas with spin-orbit couplings, enabling polarized currents without magnetic field gradients.

Contribution

It introduces a novel interferometric device design utilizing Rashba and Dresselhaus effects for efficient spin filtering in semiconductor systems.

Findings

Two regimes for spin filtering identified: symmetric arms with magnetic flux, asymmetric arms with phase shifts.

Optimal electron polarization achievable within typical 2D electron gas parameters.

Device operates effectively over broad energy ranges and for arbitrary incoming polarizations.

Abstract

A spin filtering device using quantum spin interference is theoretically proposed in a GaAs/AlGaAs electron gas that has both Rashba and Dresselhaus spin-orbit couplings. The device achieves polarized electron currents by separating spin up and spin down components without a magnetic field gradient. We find two broad spin filtering regimes, one where the interferometer has symmetrical arms, where a small magnetic flux is needed to achieve spin separation, and the other with asymmetric arms where the change in path length renders an extra phase emulating the effects of a magnetic field. We identify operating points for the device where optimal electron polarization is achieved within value ranges found in a 2D electron gas. Both device setups apply for arbitrary incoming electron polarization and operate at broad energy ranges within the incoming electron band.