Spin-flip Dynamics of Excitons in GaAs Quantum Wells

Abstract

Several recent studies [1–3] have attempted to determine how excitons in quantum wells can flip their spin. In GaAs quantum wells, excitons in the ground state can have either total spin J=1 or J=2, since they are comprised of a spin-1/2 conduction electron and a spin-3/2 hole. While a number of studies have examined the flip from +1 to -1 spin states, little experimental work has directly addressed the processes by which J=2, or “dark,” excitons, can convert to J=1 excitons. Since J=2 excitons do not couple to a single photon, in most experiments they can not be observed, and therefore unverifiable assumptions are made about their behavior.