P. Ganitzer

A network model for the Hall insulator

A Landauer-Buttiker type back scattering between pairs of opposite directed channels is used to describe the node of a network at the saddle point of a slowly varying potential in the high magnetic field regime. We show that the network can be solved without needing a transfer matrix like used by e.g. Chalker and Coddington.

Anomalous magnetotransport in wide quantum wells

Abstract We present magneto transport experiments of quasi 3D PbTe wide quantum wells. A plateau-like structure in the Hall resistance is observed, which corresponds to the Subnikov de Haas oscillations in the same manner as known from the quantum Hall effect. The onsets of plateaux in R xy do not correspond to 2D filling factors but coincide with the occupation of 3D (bulk-) Landau levels. At the same time a non-local signal is observed which corresponds to the structure in R xx and R xy and fulfils exactly the Onsager-Casimir relation [ R ij , kl ( B ) = R kl , ij (− B )]. We explain the behaviour in terms of edge channel transport which is controlled by a permanent backscattering across a system of “percolative EC-loops” in the bulk region. Long range potential fluctuations with an amplitude of the order of the subband splitting are explained to play an essential role in this electron system.

Magnetic field induced metal-to-insulator transition in wide quantum wells

Abstract We present a systematic experimental study of the magnetic field induced metal–insulator transition in high mobility quasi-3D wide quantum wells. Depending on carrier density and carrier mobility we observe both a metal-like and insulator-like temperature dependence as well as a magnetic field induced transition between both regimes.

Conductance fluctuations in PbTe wide parabolic quantum wells

Abstract We report on conductance fluctuations which are observed in local and non-local magnetotransport experiments. Although the Hall bar samples are of macroscopic size, the amplitude of the fluctuations from the local measurements is close to e2/h. It is shown that the fluctuations have to be attributed to edge channel effects.