Charge and spin photocurrents in the Rashba model

TL;DR

This paper investigates laser-induced charge and spin currents in the Rashba model, revealing a magnetic photogalvanic effect and strong spin currents in nonmagnetic systems, with potential relevance to experimental magnetic bilayer systems.

Contribution

It demonstrates the magnetic photogalvanic effect in the Rashba model and shows laser pulses can generate significant spin currents, advancing understanding of optoelectronic phenomena in inversion asymmetric materials.

Findings

Magnetic photogalvanic effect can be comparable to experimental photocurrents.

Femtosecond laser pulses induce strong spin currents in nonmagnetic Rashba systems.

Charge and spin photocurrents are tunable via system parameters.

Abstract

In metallic noncentrosymmetric crystals and at surfaces the response of spin currents and charge currents to applied electric fields contains contributions that are second order in the electric field, which are forbidden by symmetry in centrosymmetric systems. Thereby, photocurrents and spin photocurrents can be generated in inversion asymmetric metals by the application of femtosecond laser pulses. We study the laser-induced charge current in the ferromagnetic Rashba model with in-plane magnetization and find that this \textit{magnetic photogalvanic effect} can be tuned to be comparable in size to the laser-induced photocurrents measured experimentally in magnetic bilayer systems such as Co/Pt. Additionally, we show that femtosecond laser pulses excite strong spin currents in the nonmagnetic Rashba model when the Rashba parameter is large.