Spin transport of electrons through quantum wires with spatially-modulated strength of the Rashba spin-orbit interaction

TL;DR

This paper investigates how spatially-modulated Rashba spin-orbit interaction in quantum wires affects spin-polarized electron transport, revealing conditions for spin transmission control and potential applications in spin transistors.

Contribution

It provides analytical expressions for electron transmission considering subband mixing and demonstrates the impact of SOI modulation on spin transport in quantum wires.

Findings

Square-wave spin transmission in structures with periodic SOI modulation.

Transmission is affected by SOI interfaces and subband mixing when multiple subbands are occupied.

Potential application to spin transistors based on modulated Rashba interaction.

Abstract

We study ballistic transport of spin-polarized electrons through quantum wires in which the strength of the Rashba spin-orbit interaction (SOI) is spatially modulated. Subband mixing, due to SOI, between the two lowest subbands is taken into account. Simplified approximate expressions for the transmission are obtained for electron energies close to the bottom of the first subband and near the value for which anticrossing of the two lowest subbands occurs. In structures with periodically varied SOI strength, {\it square-wave} modulation on the spin transmission is found when only one subband is occupied and its possible application to the spin transistor is discussed. When two subbands are occupied the transmission is strongly affected by the existence of SOI interfaces as well as by the subband mixing.