Conductance of a quantum wire in a longitudinal magnetic field

We examine the ballistic conductance of a quantum wire in a parallel magnetic field in the presence of several impurities and derive analytic 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 steps. The number of such peaks is determined by the distance between the impurities and the energy of the scattered particle. We also study the conductivity of a quantum wire in the region where the transport mechanism is diffusive. The conductivity is examined for the case in which charge carriers are scattered by randomly distributed point impurities. We study Shubnikov-de Haas oscillations in such a system. The general oscillation pattern consists of broad minima separated by irregularly spaced sharp peaks of the burst type. (C) 1998 American Institute of Physics.