Spin accumulation in photo-induced potential dimples generated in semiconductors

Abstract

Conventional ways of confining charges in semiconductors employ advanced lithographic and crystal-growth techniques. The construction of micro/nano-scale structures is also essential for manipulating spins. However, existing techniques are not always flexible enough to control spins in appropriate positions and timings. Here we report an alternative mechanism, which enables us to design temporal and reconfigurable low-dimensional potentials. The formation of photo-induced potential dimples is deduced from time and spatially-resolved Kerr rotation measurements performed on a GaAs quantum well. Two-dimensional images of spin distributions reveal that the photo-injected electron spins in a small area illuminated by a pump light survive for a time that is two orders of magnitude longer than typical recombination lifetimes. The Kerr rotation dependence on the pump laser conditions implies that the temporally generated dimple-shaped potential profile induced by remote charges effectively confines the electrons and enhances the spin lifetime determined by fluctuating spin-orbit effective magnetic fields.