Pure spin current generation in a Rashba-Dresselhaus quantum channel

TL;DR

This paper presents a method to generate tunable pure spin currents in a quantum channel using an ac gate voltage to modulate Rashba spin-orbit interaction, enabling non-magnetic control of spin flow.

Contribution

It introduces a spin pump mechanism utilizing dynamic Rashba modulation in a quantum channel with combined Rashba and Dresselhaus interactions, analyzed via spin-resolved Floquet scattering.

Findings

Pure spin current with tunable intensity and polarization achieved.

Spin current comprises competing spin-preserved and spin-flip components.

Device allows non-magnetic control of spin flow through gate voltage and frequency tuning.

Abstract

We demonstrate a spin pump to generate pure spin current of tunable intensity and polarization in the absence of charge current. The pumping functionality is achieved by means of an ac gate voltage that modulates the Rashba constant dynamically in a local region of a quantum channel with both static Rashba and Dresselhaus spin-orbit interactions. Spin-resolved Floquet scattering matrix is calculated to analyze the whole scattering process. Pumped spin current can be divided into spin-preserved transmission and spin-flip reflection parts. These two terms have opposite polarization of spin current and are competing with each other. Our proposed spin-based device can be utilized for non-magnetic control of spin flow by tuning the ac gate voltage and the driving frequency.