Decay of spin polarized hot carrier current in a quasi one-dimensional spin valve structure

We study the spatial decay of spin polarized hot carrier current in a spin-valve structure consisting of a semiconductor quantum wire flanked by half-metallic ferromagnetic contacts. The current decays because of D'yakonov-Perel' spin relaxation in the semiconductor caused by Rashba spin orbit interaction. The associated relaxation length is found to decrease with increasing lattice temperature (in the range 30-77 K) and exhibit a non-monotonic dependence on the electric field driving the current. The relaxation lengths are several tens of microns which are at least an order of magnitude larger than what has been theoretically calculated for two-dimensional structures at comparable temperatures, Rashba interaction strengths and electric fields. This improvement is a consequence of one-dimensional carrier confinement that does not necessarily suppress carrier scattering, but nevertheless suppresses D'yakonov-Perel' spin relaxation.