Spin Polarization of Photoelectrons in GaAs Excited by Twisted Photons

TL;DR

This paper provides a theoretical analysis of how twisted photons influence the spin polarization of photoelectrons in GaAs, revealing the interplay of photon angular momentum and electron spin near phase singularities.

Contribution

It introduces a theoretical framework for calculating position-dependent electron polarization induced by twisted photons in GaAs, highlighting the effects of photon angular momentum on electron spin states.

Findings

Photon angular momentum affects electron polarization magnitude and sign.

Polarization varies near the photon's phase singularity.

Theoretical predictions show interplay of spin and orbital angular momentum.

Abstract

Inter-band photo-excitation of electron states with the twisted photons in GaAs, a direct band-gap bulk semiconductor, is considered theoretically. Assuming linearity of the quantum transition amplitudes and applying Wigner-Eckart theorem, we derive a plane-wave expansion of twisted-photon amplitudes and obtain relative probabilities for magnetic sub-level population of the photo-electrons in conduction band. The approach for calculating the position dependent electron polarization, resulting from photo-absorption of twisted light, is described for vertical transitions in the $\Gamma$ - point. Theoretical predictions for GaAs show the interplay of spin and orbital angular momentum of the twisted photons that alters the magnitude and the sign of photoelectron polarization in the region near photon's phase singularity.