Spin transmission control in helical magnetic fields

TL;DR

This paper explores how to control spin transport in two-dimensional waveguides with spatially varying magnetic fields, demonstrating tunable backscattering and potential for spin transistor applications.

Contribution

It introduces a mechanism to tune spin backscattering using Landau-Zener transitions in modulated Zeeman energy bands, tolerant to certain scattering processes.

Findings

Spin backscattering rate can be controlled via Landau-Zener transitions.

Complete spin polarization leads to full backscattering and current switching.

Partially polarized systems show enhanced resistance modulation through sequential Landau-Zener transitions.

Abstract

We calculate spin transport in two-dimensional waveguides in the presence of spatially modulated Zeeman-split energy bands. We show that in a regime where the spin evolution is predominantly adiabatic the spin backscattering rate can be tuned via diabatic Landau-Zener transitions between the spin-split bands [C. Betthausen et. al., Science 337, 324 (2012)]. This mechanism is tolerant against spin-independent scattering processes. Completely spin-polarized systems show full spin backscattering, and thus current switching. In partially spin-polarized systems a spatial sequence of Landau-Zener transition points enhances the resistance modulation via reoccupation of backscattered spin-polarized transport modes. We discuss a possible application as a spin transistor.