Electromagnetic Pulse Driven Spin-dependent Currents in Semiconductor Quantum Rings

TL;DR

This paper explores how electromagnetic pulses influence charge and spin currents in semiconductor quantum rings with spin-orbit interaction, revealing controllable dynamical behaviors and phase effects.

Contribution

It introduces a detailed analysis of non-equilibrium charge and spin currents driven by electromagnetic pulses in quantum rings with Rashba SOI, highlighting the role of external flux and pulse parameters.

Findings

Dynamical charge and spin currents vary smoothly with magnetic flux.

Spin-orbit interaction acts as an SU(2) flux affecting current phases.

Oscillation period depends on ring radius and pulse delay.

Abstract

We investigate the non-equilibrium charge and spin-dependent currents in a quantum ring with a Rashba spin orbit interaction (SOI) driven by two asymmetric picosecond electromagnetic pulses. The equilibrium persistent charge and persistent spin-dependent currents are investigated as well. It is shown that the dynamical charge and the dynamical spin-dependent currents vary smoothly with a static external magnetic flux and the SOI provides a SU(2) effective flux that changes the phases of the dynamic charge and the dynamic spin-dependent currents. The period of the oscillation of the total charge current with the delay time between the pulses is larger in a quantum ring with a larger radius. The parameters of the pulse fields control to a certain extent the total charge and the total spin-dependent currents. The calculations are applicable to nano-meter rings fabricated in heterojuctions of III-V and II-VI semiconductors containing several hundreds electrons.