Abstract
Until recently, most work in the area of mesoscopic devices and quantum wire transport has assumed the free-electron model, assuming non-interacting spin-free electrons. We introduce electron-electron interactions, electron spin and microscopic crystal properties into the design of experimental mesoscopic device structures. This work results in the prediction of spontaneous (i.e. without an externally applied magnetic field) spin-polarization effects in quantum wire transport. We have analysed electron-pair scattering for two-dimensional electrons and show that scattering for electron pairs is much reduced for partners with parallel spin. More dramatically, in quantum wires, only scattering for pairs with opposite spins is possible. We show that electron-pair scattering rates can be dramatically different for the two spin subbands of a thin quantum wire and we show the construction principle of an active spin polarizer based on this effect. Hot electrons in one subband (e.g. ‘spin up’) pass such a device with weak electron-pair scattering, while electrons in the opposite subband (e.g. ‘spin down’) have a high conversion probability into the ‘spin-up’ subband, resulting in spin polarization of a -hot-electron beam. In a differently constructed device, a hot-electron beam passing through a single-mode quantum wire may induce steady-state magnetization of the background electron gas in a section of a quantum wire.