Long spin relaxation in self-assembled InAlAs quantum dots observed by heterodyne four-wave mixing

Abstract

Exciton spin relaxation in self-assembled InAlAs quantum dots was investigated by three-pulse four-wave mixing under resonant conditions. The concept of the spin grating holds well for quantum dots and the measurements combined with optical heterodyne detection at 10K demonstrates that the exciton spin relaxation lasts up to a few nanoseconds and the time constant is ∼5 times larger than the exciton recombination time on average.