Controlling the spin orientation of photoexcited electrons by symmetry breaking

TL;DR

This paper investigates how symmetry breaking during reflection of spin-polarized hot electrons can be used to probe and control the spin orientation in semiconductors, revealing the influence of crystal symmetry and spin-orbit coupling.

Contribution

It introduces a method to control electron spin orientation via symmetry breaking reflection, linking crystal symmetry, spin precession, and spin-momentum correlation in semiconductors.

Findings

Reflection causes tipping of net-spin vector out of light direction.

Crystal symmetry influences spin precession and orientation.

Distinct signatures observed in heterostructures and ferromagnet systems.

Abstract

We study reflection of optically spin-oriented hot electrons as a means to probe the semiconductor crystal symmetry and its intimate relation with the spin-orbit coupling. The symmetry breaking by reflection manifests itself by tipping the net-spin vector of the photoexcited electrons out of the light propagation direction. The tipping angle and the pointing direction of the net-spin vector are set by the crystal-induced spin precession, momentum alignment and spin-momentum correlation of the initial photoexcited electron population. We examine non-magnetic semiconductor heterostructures and semiconductor/ferromagnet systems and show the unique signatures of these effects.