Resonant amplification of spin transferred across a GaAs/ZnSe interface

Time-resolved Kerr rotation and resonant spin amplification are used to stu dy spin dynamics in ZnSe epilayers and across a GaAs/ZnSe interface. In acc ord with previous studies in GaAs we find that modest n doping of ZnSe epil ayers enhances spin lifetimes over three orders of magnitude at low tempera tures. Lifetimes reaching 60 ns are seen at low doping concentrations at te mperatures from 5 to 50 K. A recently developed two-color technique of time -resolved Kerr rotation is used to excite electron spins in a GaAs substrat e and to measure their arrival in an adjacent ZnSe epilayer. We find that r esonant spin amplification may be used to increase the net spin transferred to the ZnSe, and discover that interlayer transport extends spin lifetimes 100-fold. (C) 2000 American Institute of Physics. [S0021-8979(00)30408-X].