Application of narrow band-gap materials in nanoscale spin filters

We develop a simple analytical model to study the influence of different material systems on the operation of a quantum-point-contact spin filter. Such a device has been predicted to allow for local control of the spin polarization in a semiconductor, and for direct electrical detection of the induced spin polarization. Narrow band-gap semiconductors, such as InAs and InSb, are predicted to exhibit excellent spin-filter characteristics, due to their large g-factor values, and enhanced subband splittings. As a practical step towards the realization of such a spin filter, the electrical properties of InGaAs quantum wires are investigated. (C) 2002 Elsevier Science B.V. All rights reserved.