TUNING THE INTERSUBBAND TUNNELING AND UNIVERSAL CONDUCTANCE FLUCTUATIONS WITH AN INPLANE MAGNETIC-FIELD IN THE QUANTUM TRANSPORT REGIME

Magnetotransport measurements are reported on mesoscopic wire samples containing tunnelling-coupled two-dimensional electron gases (2DEGs) c onfined on opposite sides of a single wide quantum well. An in-plane m agnetic field 'tunes' the tunnelling between the 2DEGs and controls th e number of occupied magnetoelectric subbands. It is found that in mes oscopic wires extra disorder quenches the resistance resonance observe d in macroscopic Hall-bars. Universal conductance fluctuations are obs erved in a parallel magnetic field, reflecting the three-dimensional n ature of electron trajectories, even in the limit of only one occupied subband. (C) 1997 Academic Press Limited.