Dynamic polarization of electron spins in indirect band gap (In,Al)As/AlAs quantum dots in weak magnetic field: experiment and theory

Abstract

A novel spin orientation mechanism -dynamic electron spin polarization has been recently suggested in Phys. Rev. Lett. 125, 156801 (2020). It takes place for unpolarized optical excitation in weak magnetic fields of the order of a few millitesla. In this paper we demonstrate experimentally and theoretically that the dynamic electron spin polarization degree changes sign as a function of time, strength of the applied magnetic field and its direction. The studies are performed on indirect band-gap (In,Al)As/AlAs quantum dots and their results are explained in the framework of a theoretical model developed for our experimental setting.

Dynamic Valley Polarization in Moire Quantum Dots

“…For transient excitons the dynamic valley polarization mechanism has some similarities with the magnetic circular polarization effect [46]. However it is unrelated with the unequal thermal population of the excitonic levels and involves the electron-nuclear spin flips [47,48].…”