Tuning the inter-subband tunnelling and universal conductance fluctuations with an in-plane magnetic field in the 'quantum transport regime'

Magnetotransport measurements are reported on mesoscopic wire samples containing tunnelling-coupled two-dimensional electron gases (2DEGs) confined on opposite sides of a single wide quantum well. An in-plane magnetic field ‘tunes’ the tunnelling between the 2DEGs and controls the number of occupied magnetoelectric subbands. It is found that in mesoscopic wires extra disorder quenches the resistance resonance observed in macroscopic Hall-bars. Universal conductance fluctuations are observed in a parallel magnetic field, reflecting the three-dimensional nature of electron trajectories, even in the limit of only one occupied subband.