Spin Transport in Nanowires

We study high-field spin transport of electrons in a quasi one-dimensional channel of a GaAs gate controlled spin interferometer (SPINFET) using a semiclassical formalism (spin density matrix evolution coupled with Boltzmann transport equation). Spin dephasing (or depolarization) is predominantly caused by D’yakonov-Perel’ relaxation associated with momentum dependent spin orbit coupling effects that arise due to bulk inversion asymmetry (Dresselhaus spin orbit coupling) and structural inversion asymmetry (Rashba spin orbit coupling). Spin dephasing length in a one dimensional channel has been found to be an order of magnitude higher than that in a two dimensional channel. This study confirms that the ideal configuration for a SPINFET is one where the ferromagnetic source and drain contacts are magnetized along the axis of the channel. The spin dephasing length in this case is about 22.5μm at lattice temperature of 30K and 10μm at lattice temperature of 77K for an electric field of 2kV/cm. Spin dephasing length has been found to be weakly dependent on the driving electric field and strongly dependent on the lattice temperature.