CONDUCTANCE OF A QUANTUM-WIRE IN A LONGITUDINAL MAGNETIC-FIELD

We examine the ballistic conductance of a quantum wire in a parallel m agnetic field in the presence of several impurities and derive analyti c expressions for the transmission coefficient and the conductance in such a system. We show that scattering by impurities leads to a number of sharp peaks near the thresholds of the conductance quantization st eps. The number of such peaks is determined by the distance between th e impurities and the energy of the scattered particle. We also study t he conductivity of a quantum wire in the region where the transport me chanism is diffusive. The conductivity is examined for the case in whi ch charge carriers are scattered by randomly distributed point impurit ies. We study Shubnikov-de Haas oscillations in such a system. The gen eral oscillation pattern consists of broad minima separated by irregul arly spaced sharp peaks of the burst type. (C) 1998 American Institute of Physics.