Dependence of the longitudinal resistance on edge potential and electron density in quantum Hall systems

Differently prepared mesas of the same wafer yield different longitudinal r esistances rho(xy)(B) in the quantum Hall regime. The ratio of two neighbor ing spin-split maxima is constant for one sample, but varies from sample to sample. We assume an exponential law for the short-range elastic edge chan nel scattering rate 1/tau(el)(n,n+1) proportional to exp(- const.gamma n(2D )l(depl)) where gamma is spin-dependent, l(depl) the depletion length and n (2D) the electron density. Different depiction lengths can explain the meas urements mentioned above. Furthermore, experiments with in-plane gates defi ned with focussed ion beam writing or mechanical scratching verify this dep endence. Measurements under illumination confirm the dependence on l(depl) and n(2D.) (C) 2000 Elsevier Science B.V. All rights reserved.