QUENCHING MECHANISMS OF NONLOCAL TRANSPORT IN LATERALLY CONFINED 2-DIMENSIONAL SYSTEMS

Non-Ohmic and sample-size-dependent transport effects [i.e., Shubnikov -de Haas (SdH) and quantum Hall effect] of mesoscopic two-dimensional (2D) systems prove the occurrence of nonlocal contributions to the ele ctronic conductance in these systems. However, this nonlocal regime ac companied by a nonequilibrium population of the edge states with respe ct to the 2D bulk state is quenched at rather low values of external e lectric fields or flowing currents, respectively. Beyond this quench, the bulk state is coupled to the edge by an increasing amount of elect ron transitions between the corresponding states. We analyze the non-O hmic behavior of SdH oscillations at GaAs/GaxAl1-xAs quantum Hall cond uctors on the basis of a model including edge and bulk transport. We d educe the current-dependent nonequilibrium population of edge and bulk states quantitatively. Further, we give estimates for the current ran ges in which transitions of electrons between edge and bulk states due to elastic and inelastic scattering are relevant. The change of the t ypical nonequilibrium parameters as the equilibration length and the m aximal difference of chemical potentials of edge and bulk states in ti lted magnetic fields are also discussed.