Magnetization generated by microwave-induced Rashba interaction

TL;DR

This paper demonstrates that microwave-induced spin-orbit interactions in a quantum dot junction can generate controllable dc magnetization, with the effect depending on electric field polarization and microwave photon energy.

Contribution

It introduces a method to induce and control dc magnetization via microwave-driven Rashba interaction in quantum dot junctions, highlighting polarization dependence and energy thresholds.

Findings

Maximal magnetization with circular polarization

Magnetization increases stepwise with photon energy

Effect is temperature-dependent and absent with linear polarization

Abstract

We show that a controllable dc magnetization is accumulated in a junction comprising a quantum dot coupled to non-magnetic reservoirs if the junction is subjected to a time-dependent spin-orbit interaction. The latter is induced by an ac electric field generated by microwave irradiation of the gated junction. The magnetization is caused by inelastic spin-flip scattering of electrons that tunnel through the junction, and depends on the polarization of the electric field: a circularly polarized field leads to the maximal effect, while there is no effect in a linearly polarized field. Furthermore, the magnetization increases as a step function (smoothened by temperature) as the microwave photon energy becomes larger than the absolute value of the difference between the single energy level on the quantum dot and the common chemical potential in the leads.