Photo-induced pure spin currents in quantum wells

TL;DR

This paper demonstrates that unpolarized light absorption in quantum wells can generate pure spin currents without net electron spin polarization or electric current, revealing a new optical spin transport mechanism.

Contribution

It introduces a novel phenomenon where unpolarized light induces pure spin currents in quantum wells, expanding understanding of optical spin control.

Findings

Unpolarized light can generate pure spin currents in quantum wells.

No net electron spin polarization or electric current occurs during this process.

The phenomenon broadens potential for optical spin manipulation in semiconductors.

Abstract

As is well known the absorption of circularly polarized light in semiconductors results in optical orientation of electron spins and helicity-dependent electric photocurrent, and the absorption of linearly polarized light is accompanied by optical alignment of electron momenta. Here we show that the absorption of unpolarized light in a quantum well (QW) leads to generation of a pure spin current, although both the average electron spin and electric current are vanishing.