Oscillating spin-orbit interaction in two-dimensional superlattices: sharp transmission resonances and time-dependent spin polarized currents

TL;DR

This paper investigates how oscillating Rashba spin-orbit interaction in a 2D superlattice creates unique transmission resonances and propagating spin-polarization waves, expanding understanding of dynamic spin transport.

Contribution

It introduces a novel analysis of time-dependent SOI effects in superlattices using Floquet theory, revealing new resonance phenomena and spin-polarization dynamics.

Findings

Transmission peaks appear in mini-bandgaps due to oscillating SOI.

Harmonics of the driving frequency enable resonances not possible in static cases.

Space and time-dependent spin polarization waves propagate through the superlattice.

Abstract

We consider ballistic transport through a lateral, two-dimensional superlattice with experimentally realizable, sinusoidally oscillating Rashba-type spin-orbit interaction. The periodic structure of the rectangular lattice produces a spin-dependent miniband structure for static SOI. Using Floquet theory, transmission peaks are shown to appear in the mini-bandgaps as a consequence of the additional, time-dependent SOI. A detailed analysis shows that this effect is due to the generation of harmonics of the driving frequency, via which e.g., resonances that cannot be excited in the case of static SOI become available. Additionally, the transmitted current shows space and time-dependent partial spin-polarization, in other words, polarization waves propagate through the superlattice.