Measurements of spin polarization and spin relaxation in 2D electron gases

Pure spin currents are generated and detected using quantum point contacts in narrow channels of a GaAs/AlGaAs 2D electron gas. A spin relaxation length of 50 microns is achieved due to a cancellation of Rashba and Dresselhaus spin-orbit interactions along 110 crystal direction. Spin currents observed at zero magnetic field are correlated with the 0.7 conductance feature of quantum point contacts, suggesting static spontaneous spin polarization.