Spin polarized transport in 1D and 2D semiconductor heterostructures

The high electron mobility spin transistor comprises a 1D or 2D electron gas, obtained from III-V semiconductor heterostructure, with ferromagnetic source and drain contacts. The latter act respectively as a polarizer and as an analyzer for the spin of the electrons, and the gate potential is used to control the spin precession in the channel. After reviewing the main spin dephasing effects existing in m-V heterostructures, we present the model that we develop to investigate the spin polarized transport in the channel of a HEMT. The results obtained from this model show that in a 2D electron gas the spin polarization is randomized by the scattering events, which leads to non negligible loss of spin polarization. However, this spin relaxation vanishes if the width of the 2D-channel is sufficiently reduced, or if a 1D-channel is used. In these conditions, the gate-controlled spin rotation may yield a large negative transconductance effect. We discuss finally the spin-dependent injection/collection from ferromagnets.