Quantized conductance of magnetoelectric subbands in ballistic point contacts

Abstract

The two-terminal conductance of ballistic point contacts in the two-dimensional electron gas of a high-mobility $\frac{\mathrm{GaAs}}{{\mathrm{Al}}_x{\mathrm{Ga}}_{1-x}\mathrm{As}}$ heterostructure has been studied in quantizing electric and magnetic fields. The conductance is found to be quantized at multiples of $\frac{e^2}{h}$, exclusively determined by the number of occupied magnetoelectric subbands in the constriction. The experiment provides the first direct demonstration of magnetic and electric depopulation of one-dimensional subbands in a single wire.