SPIN-RELAXATION PROCESS OF HOLES IN TYPE-II AL0.34GA0.66AS ALAS MULTIPLE-QUANTUM WELLS/

We have measured the spin memory and the spin-relaxation times of hole s in type-II quantum wells by means of pump-and-probe methods. The fas t GAMMA-x interlayer scattering which is characteristic of type-II mul tiple quantum wells allows us to observe directly the hole spin-relaxa tion process. The hole spin relaxation is described by two decay compo nents. The faster decay time ranges from 20 to 100 ps and depends on t he number density of ''antiparallel-spin'' holes. This indicates that the scattering between up-spin holes and down-spin holes is the major spin-relaxation process of holes. The slower time component is about 2 0 ns, which is probably ascribed to the spin relaxation of localized h oles in the well layers.