Dynamical Spin-Orbit-Based Spin Transistor

TL;DR

This paper introduces a spin transistor leveraging dynamical and inhomogeneous Rashba spin-orbit interaction to generate, manipulate, and detect pure spin currents and convert them into charge signals, expanding the capabilities of spintronic devices.

Contribution

It presents a novel spin transistor design that combines dynamical SOI with gauge theory and Onsager relations for efficient spin current control and detection, beyond traditional adiabatic methods.

Findings

Pure spin currents of several hundred nano-Amperes generated.

Analytical expressions for spin and charge conductance derived.

Predictions validated by numerical simulations across various frequencies.

Abstract

Spin-orbit interaction (SOI) has been a key tool to steer and manipulate spin-dependent transport properties in two-dimensional electron gases. Here we demonstrate how spin currents can be created and efficiently read out in nano- or mesoscale conductors with time-dependent and spatially inhomogeneous Rashba SOI. Invoking an underlying non-Abelian SU(2) gauge structure we show how time-periodic spin-orbit fields give rise to spin electric forces and enable the generation of pure spin currents of the order of several hundred nano-Amperes. In a complementary way, by combining gauge transformations with "hidden" Onsager relations, we exploit spatially inhomogeneous Rashba SOI to convert spin currents (back) into charge currents. In combining both concepts, we devise a spin transistor that integrates efficient spin current generation, by employing dynamical SOI, with its experimentally feasible detection via conversion into charge signals. We derive general expressions for the respective spin- and charge conductance, covering large parameter regimes of SOI strength and driving frequencies, far beyond usual adiabatic approaches such as the frozen scattering matrix approximation. We check our analytical expressions and approximations with full numerical spin-dependent transport simulations and demonstrate that the predictions hold true in a wide range from low to high driving frequencies.