Subpicosecond spin relaxation dynamics of excitons and free carriers in GaAs quantum wells

We have obtained a coherent understanding of spin relaxation processes of electrons, holes, and excitons in quantum walls by investigating subpicosecond dynamics of luminescence polarization. We show that the spin behavior for electrons and holes in quasi-two-dimensional systems is distinct from that in bulk semiconductors and that many-body effects and formation process play an important role in exciton spin relaxation.