Anomalous magnetotransport in wide quantum wells

TL;DR

This study investigates anomalous magnetotransport in wide quantum wells, revealing 3D Landau level occupation, edge channel transport, and the influence of potential fluctuations, challenging traditional 2D quantum Hall interpretations.

Contribution

It introduces a novel explanation for magnetotransport phenomena in wide quantum wells involving 3D Landau levels and bulk edge channel transport mechanisms.

Findings

Observation of plateau-like structures in Hall resistance linked to 3D Landau levels.

Non-local signals obeying Onsager-Casimir relations indicate edge channel transport.

Long-range potential fluctuations significantly influence electron behavior.

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 Shubnikov de Haas oscillations in the same manner as known from the quantum Hall effect. The onsets of plateaux in Rxy 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 Rxx and Rxy and fulfils exactly the Onsager-Casimir relation (Rij,kl(B) = Rkl,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.