Spin precession and laser-induced spin-polarized photocurrents

TL;DR

This paper proposes a method to generate controllable, spin-polarized photocurrents in topological insulators using circularly polarized light and gate-tunable Rashba spin-orbit coupling, enabling light-controlled spintronic devices.

Contribution

It introduces a theoretical approach to induce switchable spin-polarized photocurrents in TIs via Floquet engineering and rSOC, advancing topological spintronics.

Findings

Laser irradiation creates Floquet sidebands enabling spin control.

rSOC induces controllable spin precession in driven TIs.

Switchable, one-way spin-polarized photocurrents are achievable.

Abstract

Controlling spin currents in topological insulators (TIs) is crucial for spintronics but challenged by the robustness of their chiral edge states, which impedes the spin manipulation required for devices like spin-field effect transistors (SFETs). We theoretically demonstrate that this challenge can be overcome by synergistically applying circularly polarized light and gate-tunable Rashba spin-orbit coupling (rSOC) to a 2D TI. Laser irradiation provides access to Floquet sidebands where rSOC induces controllable spin precession, leading to the generation of one-way, switchable spin-polarized photocurrents, an effect forbidden in equilibrium TIs. This mechanism effectively realizes SFET functionality within a driven TI, specifically operating within a distinct Floquet replica, offering a new paradigm for light-based control in topological spintronics.