PREDICTION OF SPIN-POLARIZATION EFFECTS IN QUANTUM-WIRE TRANSPORT

We predict a new effect for transport in quantum wires: spontaneous sp in polarization. Most work on transport in mesoscopic devices has assu med a model of non interacting, spin-free electrons. We introduce spin , electron pair scattering and microscopic crystal properties into the design of mesoscopic devices. The new spin polarization effect result s from tile fact that in a single mode quantum wire, electron and hole bands still have two spin subbands. In general, these two spin subban ds are expected to be split even in zero magnetic field. At sufficient ly low temperatures the electron pair scattering rates for one spin su bband (e.g., the spin-down) can be much larger than for the other spin subband. This effect can be used for an active spin polarizer device: hot electrons in one subband (e.g.,'spin up') pass with weak pair sca ttering, while electrons in the opposite subband (e.g.,:spin down'), h ave high probability of scattering into the 'spin-up' subband, resulti ng in spin polarization of a hot electron beam.