Spin polarization of exciton luminescence from orderedGa0.5In0.5P

Circularly polarized excitation light produces spin-polarized excitons in long-range ordered ${\mathrm{Ga}}_{0.5}{\mathrm{In}}_{0.5}\mathrm{P}$ because of a splitting at the valence-band maximum. We observed the spin-relaxation process in ordered ${\mathrm{Ga}}_{0.5}{\mathrm{In}}_{0.5}\mathrm{P}$ under resonant excitation of heavy-hole excitons. The circularly polarized exciton luminescence shows a maximum anisotropy of about 53%. The decay profile of the polarized luminescence is described by two components: the rapid decay by exciton-relaxation processes and the slower exciton recombination. The relaxation of the exciton-spin polarization obeys a decay with a time constant of 105 ps.