Resonant magneto-transport through a lateral quantum box in a semiconductor heterostructure

Abstract

The authors have investigated magneto-transport through a lateral quantum box defined by a patterned Schottky barrier on a GaAs-AlGaAs heterojunction. As the size of the box, and the reflecting barrier potential, are varied, edge states are successively reflected with a consequent change in the value of the plateaux of resistance. Superimposed on a plateau are modulations of resistance having both electrical and magnetic origin. Resonant transport, with an increase in transmission ratio to unity, (corresponding to oscillations in resistance at, or above, the plateaux values), occurs when an integer number of wavelengths fit into the box perimeter and are rapidly modulated by flux quantisation of the Aharonov-Bohm type. In addition, resonance can arise when an incident wave tunnels through the barriers via a circulating, trapped, edge current. This behaviour brings in an extra mode of current and causes the resistance to drop below the value of a plateau in contrast to the previously mentioned resonance arising from transport above the barrier.