Dynamics of Photo-excited Spins in InSb Based Quantum Wells

We report time resolved measurements of spin relaxation in doped and undoped InSb quantum wells using degenerate and two-color magneto-optical Kerr effect techniques. We observed that the photo-excited spin dynamics are strongly influenced by laser excitation fluence and the doping profile of the samples. In the low fluence regime, an oscillatory pattern was observed at low temperatures ($\le$ 77 K) in the samples with an asymmetric doping profile which might be attributed to the quasi-collision-free spin relaxation regime. Our measurements also suggest the influence of the barrier materials (Al${}_x$In${}_{1-x}$Sb) on the spin relaxation in these material systems.