Spin-transport dynamics of optically spin-polarized electrons in GaAs quantum wires

We investigate the drift and diffusion dynamics of optically spin-polarized electrons in p-type rectangular GaAs/AlAs quantum wires with small (10 nm) lateral sizes by time- and spatially resolved photoluminescence measurement. The drift process causes a rapid expansion of the spin-polarized electrons, keeping the spin polarization beyond by 10 μm. We theoretically analyze the transport characteristics of spin-polarized electrons and their spin-relaxation dynamics based on a drift-diffusion model which includes a spin-flip process. Experiment can be consistently explained by considering that the dependence of the diffusivity and mobility on the degree of the spin polarization, demonstrating the possibility of spin-dependent electron-electron scattering that affects the transport properties in one-dimensional structures.