Spin relaxation in (110) and (001) InAs/GaSb superlattices -: art. no. 115311

We report an enhancement of the electron spin-relaxation time (T-1) in a (110) InAs/GaSb superlattice by more than an order of magnitude (25 times) relative to the corresponding (001) structure. The spin dynamics were measured using polarization sensitive pump probe techniques and a mid-infrared, subpicosecond periodically poled LiNbO3 optical parametric oscillator. Longer T-1 times in (110) superlattices are attributed to the suppression of the native interface asymmetry and bulk inversion asymmetry contributions to the precessional D'yakonov Perel spin-relaxation process. Calculations using a nonperturbative 14-band nanostructure model give good agreement with experiment and indicate that possible structural inversion asymmetry contributions to T-1 associated with compositional mixing at the superlattice interfaces may limit the observed spin lifetime in the (110) superlattice under study, suggesting the possibility for further improvements in T-1 through targeted growth techniques. Our findings have implications for spintronics applications using InAs/GaSb heterostructures.