Spin relaxation in undoped GaAs quantum wells

Summary form only given.We describe comprehensive measurements of spin relaxation in undoped MBE GaAs-Al/sub 0.35/Ga/sub 0.65/As quantum wells at room temperature and down to 10 K. Samples from several sources have been investigated and are compared with results from other workers. We used a pump-probe quasi-normal-incidence reflection technique based on a ps mode-locked Ti:sapphire laser. The pump and delayed weak probe beams were tuned to the n=1 heavy-hole exciton feature in each sample and were circularly and linearly polarized, respectively.