MAGNETOCONDUCTANCE OF A NANOSCALE ANTIDOT

A 300-nm-diameter gate is used to introduce an antidot or artificial i mpurity into a quantum wire defined in an AlxGa1-xAs/GaAs two-dimensio nal electron gas. At low magnetic fields, geometry-induced quantum int erference effects are observed, while at higher fields adiabatic edge- state transport is established. In the transitional regime, conductanc e resonances due to magnetically bound impurity states exhibit distinc t characteristics including beating, sharp period changes, and spin sp litting. An asymmetry is observed between the resonances observed as a function of magnetic field and gate voltage. The results are explaine d by a model based on an interedge-state coupling mechanism.