High-density photogenerated free-carrier spin relaxation processes in Wurtzite semiconductors: CdSe and semimagnetic semiconductor Cd/sub 1-x/Mn/sub x/Se

Picosecond time-resolves spin relaxation kinetics of high-density free carriers is investigated at low temperatures on CdSe (x=0) and in the dilute semimagnetic semiconductor Cd/sub 1-x/Mn/sub x/Se for x=0.05 and 0.10. The fast spins relaxation observed in CdSe results from a mechanism associated with the noncentrosymmetric character of the band structure for this material. This process is similar to the one proposed by M.I. D´yakonov and V.I. Perel´ (1971) for the zinc blende crystal structures. The spin relaxation times in CdSe are on the order of 30 ps. The spin relaxation time are <20 ps in semimagnetic semiconductor Cd/sub 1-x/MnSe and are consistent with spin-flip Raman scattering measurements. The increase in spin relaxation rate relative to CdSe is explained in terms of the carrier spin exchange between the carriers and the magnetic spin sites. A probable cause for the reduction in the observed spin polarization factor for carriers in Cd/sub 1-x/Mn/sub x/Se (x not=0) is presented.<>