Relation between spin and momentum relaxation in ZnSe/ZnMgSSe quantum wells

First, are measure the coherence time of optically oriented carrier spins i n wide gap quantum wells and observe an increase with temperature from less than 10 ps at 20 K to 500 ps at 200 K. Second, we measure the temperature dependence of the momentum relaxation time by four wave mixing and absorpti on experiments. The spin relaxation time is approximately proportional to t he inverse of the momentum relaxation time. In the low-temperature regime, the strong increase of spin lifetime can be caused by motional narrowing du e to the faster scattering of excitons with increasing temperature. In the high-temperature regime, quenching of the electron-hole spin flip dephasing due to an increasing ionization of excitons with increasing temperatures c an prolongate spin lifetime. (C) 1999 Elsevier Science B.V. All rights rese rved.