Optical Orientation of Spins in Semiconductors

Spins in direct-gap semiconductors can be magnetized by shining circularly-polarized light on them. The subsequent decay of this magnetization can be watched using Faraday rotation of Kerr effect measurements. Bill Putikka and I figured out how to calculate the often rather complex time dependence of this decay. It has rather surprising temperature and field dependences that can only be understood by including the transfer of spin moment between the localized electrons and the conduction electrons.