Spin orientation and spin currents induced by linearly polarized light

TL;DR

This paper demonstrates that linearly polarized light can induce spin polarization and spin currents in low-dimensional structures, expanding the understanding of optical spin manipulation beyond circular polarization.

Contribution

It provides a microscopic theory showing how linearly polarized light causes spin effects in quantum wells, including interband and intra/subband transitions.

Findings

Linearly polarized light induces spin polarization in quantum wells.

Spin photocurrents can be generated without circular polarization.

Theoretical description covers various types of optical transitions.

Abstract

To date, optical orientation of free-carrier spins and spin currents have been achieved by circularly polarized light, while the linearly polarized light has been used for optical alignment of electron momenta. Here we show that, in low-dimensional structures, absorption of the linearly polarized light also leads to the spin polarization and spin photocurrent, and, thus, the electron and hole spins can be manipulated by light of zero helicity. The microscopic description of the both effects is developed for interband optical transitions in undoped quantum wells (QWs) as well as for direct intersubband and indirect intrasubband (Drude-like) transitions in $n$-doped QW structures.