New Physics in High Landau Levels

TL;DR

Recent experiments on high Landau levels in 2D electron systems have uncovered new correlated states, including anisotropic resistivity and re-entrant quantum Hall effects, indicating novel physics beyond the lowest Landau level.

Contribution

This paper surveys the emerging field of new correlated electron states in high Landau levels, highlighting recent experimental discoveries and their implications.

Findings

Giant resistivity anisotropies near half filling of higher Landau levels

Observation of re-entrant integer quantum Hall states

Distinct differences from fractional quantum Hall liquids in lowest Landau level

Abstract

Recent magneto-transport experiments on ultra-high mobility 2D electron systems in GaAs/AlGaAs heterostructures have revealed the existence of whole new classes of correlated many-electron states in highly excited Landau levels. These new states, which appear only at extremely low temperatures, are distinctly different from the familiar fractional quantum Hall liquids of the lowest Landau level. Prominent among the recent findings are the discoveries of giant anisotropies in the resistivity near half filling of the third and higher Landau levels and the observation of re- entrant integer quantum Hall states in the flanks of these same levels. This contribution will survey the present status of this emerging field.