Spin relaxation in (110) and (001) InAs/GaSb superlattices

Abstract

We report an enhancement of the electron spin-relaxation time (T1) 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 T1 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 T1 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 T1 through targeted growth techniques. Our findings have implications for spintronics applications using InAs/GaSb heterostructures. © 2003 The American Physical Society.