MAPPING OF QUANTUM-HALL EDGE CHANNELS BY A DILUTION-REFRIGERATOR BASED NEAR-FIELD SCANNING OPTICAL MICROSCOPE

Abstract

A real-space mapping of photovoltage near the edge of the Hall-bar of a GaAs/AlGaAs single heterojunction has been obtained using a dilution-refrigerator-based near-field scanning optical microscope in magnetic fields. The optical probe-sample surface distance dependence of photovoltage is investigated. We obtain photovoltage profile in the vicinity of the edge, which reflects the local chemical potential of the two-dimensional electron gas determined by the distribution of the compressible and incompressible strips.