Spin relaxation in InSb and InAs by 1- and 2-colour spectroscopy with free electron and solid state lasers

We report time-resolved measurement of spin lifetimes in both bulk and quantum well narrow gap semiconductors (NGSs) at 300K. We have used both free electron and solid state laser sources from 3 to 7 /spl mu/m and quarter wave plates to produce circularly polarised pump and probe beams. We previously demonstrated that spin flip (Elliott-Yafet, EY) scattering dominates in Hg/sub 0.78/Cd/sub 0.22/Te due to strong lattice scattering. In contrast, spin unphasing (D'Yakonov-Perel, DP) scattering controls the loss of polarisation in intrinsic InSb and InAs due to the higher mobility, giving spin lifetimes, /spl tau//sub s/, of /spl sim/20 ps at 300 K. We report first measurements of /spl tau//sub s/ of /spl sim/17 ps in InSb/InAlSb quantum wells.