Negative Electron Drag and Hole-Like behavior in the Integer Quantum Hall Regime

TL;DR

This paper reports the observation of negative electron drag in the integer quantum Hall regime, revealing hole-like dispersion in Landau levels and suggesting disorder as a key factor.

Contribution

It demonstrates the occurrence of negative drag linked to hole-like dispersion in Landau levels within the quantum Hall regime, a novel insight into electron interactions under magnetic fields.

Findings

Negative drag occurs only when one Landau level is more than half filled and the other less than half filled.

Hole-like dispersion is present in half of each Landau level.

Disorder is proposed as a cause for negative drag.

Abstract

Electron drag between two two-dimensional electron gases in magnetic fields has been observed with a polarity opposite that for zero field. This negative drag requires that the electrons have a hole-like dispersion. Density dependence measurements in the integer quantum Hall regime show that drag is negative only when the upper Landau level of one layer is more than half filled while the other is less than half filled, indicating that hole-like dispersion is present in a half of each Landau level. Negative drag is argued to be a consequence of disorder.