Quantum pumping and rectification effects in Aharonov-Bohm-Casher ring-dot systems

TL;DR

This paper investigates how time-dependent modulation of spin-orbit interaction and quantum dot levels in an Aharonov-Bohm-Casher ring system can generate spin currents and rectification effects, relevant for quantum transport experiments.

Contribution

It introduces a model for time-dependent charge and spin transport in ring-dot systems, revealing rectification currents and spin pumping mechanisms beyond the adiabatic approximation.

Findings

Electrically pumped spin current can be generated without charge current.

A rectification current proportional to cos(φ) is observed beyond adiabatic regime.

Results are relevant for understanding out-of-equilibrium quantum dot experiments.

Abstract

We study the time-dependent transport of charge and spin through a ring-shaped region sequentially coupled to a weakly interacting quantum dot in the presence of an Aharonov-Bohm flux and spin-orbit interaction. The time-dependent modulation of the spin-orbit interaction, or of the corresponding Aharonov-Casher flux, together with the modulation of the dot-level induces an electrically pumped spin current even in absence of a charge current. The results beyond the adiabatic regime show that an additional rectification current proportional to \cos(\phi), being \phi the relative phase between the time varying parameters, is generated. We discuss the relevance of such term in connection with recent experiments on out-of-equilibrium quantum dots.