Multichannel effects in Rashba quantum wires

TL;DR

This paper studies how multiple channels in Rashba quantum wires affect spin-dependent transport, revealing quenching of oscillations and irregular conductance behavior at high Rashba coupling, with implications for spintronic devices.

Contribution

It provides new insights into multichannel effects on spin transport and conductance oscillations in Rashba quantum wires, highlighting the impact of multiple modes on spin precession.

Findings

Oscillations in spin-transistor current are quenched with many modes.

High Rashba coupling leads to irregular conductance curves.

Conductance varies with Rashba strength and magnetization orientation.

Abstract

We investigate intersubband mixing effects in multichannel quantum wires in the presence of Rashba spin-orbit coupling and attached to two terminals. When the contacts are ferromagnetic and their magnetization direction is perpendicular to the Rashba field, the spin-transistor current is expected to depend in a oscillatory way on the Rashba coupling strength due to spin coherent oscillations of the travelling electrons. Nevertheless, we find that the presence of many propagating modes strongly influences the spin precession effect, leading to (i) a quenching of the oscillations and (ii) strongly irregular curves for high values of the Rashba coupling. We also observe that in the case of leads' magnetization parallel to the Rashba field, the conductance departs from a uniform value as the Rashba strength increases. We also discuss the Rashba interaction induced current polarization effects when the contacts are not magnetic and investigate how this mechanism is affected by the presence of several propagating channels.