Spin Hall and Edelstein effects in a ballistic quantum dot with Rashba spin-orbit coupling

TL;DR

This paper investigates how Rashba spin-orbit coupling influences spin currents and quantum interference effects in a ballistic quantum dot, revealing a crossover from weak localization to antilocalization and associated spin phenomena.

Contribution

It demonstrates the gate-tunable spin currents and the crossover behavior in a quantum dot with Rashba coupling, linking quantum coherence with spin transport in mesoscopic systems.

Findings

Crossover from weak localization to weak antilocalization with increasing Rashba strength

Gate-tunable Edelstein and spin Hall currents linked to wavefunction interference

Transition in magnetoresistance periodicity from π to 2π due to spin-orbit and Zeeman effects

Abstract

We study spin-resolved transport in a ballistic quantum dot with Rashba spin-orbit coupling, focusing on charge-to-spin conversion and spin Hall effect. In the regime where the dot size is comparable to the Fermi wavelength, we identify a clear crossover from weak localization to weak antilocalization as the Rashba coupling increases. This transition is accompanied by gate-tunable spin currents of Edelstein and spin Hall type, whose behavior reflects the underlying electron wavefunction interference. Notably, the Edelstein current shows an inflection point at the critical Rashba strength, signaling the crossover from weak localization to weak antilocalization. In the presence of an in-plane magnetic field we also report a transition in angular periodicity of the magnetoresistance -- from $\pi$ to $2\pi$ -- arising from the interplay between spin-orbit interaction and Zeeman coupling. These results establish a direct link between quantum coherence, charge-to-spin conversion, and geometric confinement in mesoscopic systems.