Anomalous conductance quantization observed in a quantum point contact with an asymmetric confinement potential

Abstract

The conductance through a quantum point contact with an asymmetric confinement potential has been studied. Multiple anomalous conductance plateaus were observed, around 0.5G0 and 0.9G0, when the confinement potential of the QPC was set to be asymmetric. Also, resonance-like conductance peaks were observed in some devices for highly asymmetric confinement potentials while some of the peaks evolved into anomalous conductance plateaus when the asymmetry was reduced. We found that the spin polarization model based on spin-orbit coupling in an asymmetric confinement potential could not directly explain our data.