Strongly Anisotropic Transport in Higher Two-Dimensional Landau Levels

TL;DR

This paper investigates the highly anisotropic electronic transport phenomena observed in higher Landau levels of a two-dimensional electron system at low temperatures, suggesting the emergence of a new many-particle state.

Contribution

It reports the discovery of strong anisotropic transport in Landau levels N>1, highlighting a potential new many-particle state exclusive to higher Landau levels.

Findings

Transport anisotropy appears only in higher Landau levels (N>1).

Anisotropic magnetoresistance depends on current direction.

Absence of anisotropy in N=0 and N=1 levels.

Abstract

Low-temperature, electronic transport in Landau levels N>1 of a two-dimensional electron system is strongly anisotropic. At half-filling of either spin level of each such Landau level the magnetoresistance either collapses to form a deep minimum or is peaked in a sharp maximum, depending on the in-plane current direction. Such anisotropies are absent in the N=0 and N=1 Landau level, which are dominated by the states of the fractional quantum Hall effect. The transport anisotropies may be indicative of a new many particle state, which forms exclusively in higher Landau levels.