Current Carrying Edge Channels and the Role of Contacts in the Quantum Hall Regime

By selectively populating spin resolved edge channels using Schottky gates we experimentally investigate the transition from adiabatic to equilibrated transport in the Quantum Hall regime. The scattering processes within a contact e. g. provide an excellent possibility to equilibrate nonequally populated edge channels. Here we demonstrate that not only with metallic reservoirs but also with increasing temperature one can study the crossover from adiabatic to equilibrated transport. Increasing the current results in a transition from edge channel to bulk transport

Novel Far-Infrared-Photodetector based on Photon Induced Interedge Channel Scattering

We demonstrate experimentally that the far- infrared photoresponse of GaAs/AlGaAs heterostructures at photon energies corresponding to cyclotron resonance absorption is strongly enhanced in the adiabatic transport regime of the quantum Hall effect (QHE). Ideal adiabatic transport is characterized within the edge channel picture of the QHE by the absence of interedge channel scattering. We realize adiabatic transport by the means of a multiple gate finger structure, which is used for a selective population of the edge channels. The cyclotron resonance absorption is interpreted as an additional interchannel scattering process increasing the magnetoresistance. Applied Physics Letters is copyrighted by The American Institute of Physics

Influence of Interedge Channel Scattering on the Magneto-Transport of 2D-Systems

We investigate the influence of interedge channel scattering (IECS) on adiabatic transport in a two-dimensional electron gas (2DEG) in the quantum Hall regime. To realize adiabatic transport (non-equal distribution of the current among the available edge channels) Schottky gates are used to create areas of different well- defined filling factors. By studying the current dependence one can identify scattering processes and learn how these processes are affected by the device structure. Irradiating the device with photons at the cyclotron resonance frequency in the adiabatic transport regime leads to a drastic change in the magneto-resistance, indicating possible application as a sensitive photoconductor. In addition, a new device structure is discussed allowing direct measurement of the IECS rate