Optical polarization of localized hole spins in p-doped quantum wells

TL;DR

This paper investigates how localized hole spins in p-doped quantum wells can be polarized using optical methods, revealing dependencies on magnetic field, pump power, and wavelength, and identifying two mechanisms responsible for spin polarization.

Contribution

It uncovers the mechanisms behind optical spin polarization of localized hole spins, highlighting the roles of g factor differences and dark exciton capture.

Findings

Spin polarization sign depends on magnetic field, pump power, and wavelength.

Two mechanisms influence spin polarization: g factor difference and dark exciton capture.

The study advances understanding of spin initialization in quantum well systems.

Abstract

The initialization of spin polarization in localized hole states is investigated using time-resolved Kerr rotation. We find that the sign of the polarization depends on the magnetic field, and the power and the wavelength of the circularly polarized pump pulse. An analysis of the spin dynamics and the spin-initialization process shows that two mechanisms are responsible for spin polarization with opposite sign: The difference of the g factor between the localized holes and the trions, as well as the capturing process of dark excitons by the localized hole states.