Nonlinear response in overlapping and separated Landau levels of GaAs quantum wells

TL;DR

This study investigates the nonlinear magnetotransport response of high-mobility GaAs quantum wells, revealing a transition from magnetic field-dependent to independent behavior linked to Landau level separation, with implications for future theoretical models.

Contribution

It provides experimental evidence of a crossover in nonlinear response behavior associated with Landau level overlap and separation in GaAs quantum wells.

Findings

At low B, resistivity correction scales with -λ^2 j^2 / B^2.

At higher B, resistivity correction becomes B-independent, scaling with -j^2.

The crossover is linked to Landau level separation, but full theoretical understanding remains open.

Abstract

We have studied magnetotransport properties of a high-mobility two-dimensional electron system subject to weak electric fields. At low magnetic field $B$, the differential resistivity acquires a correction $\delta r \propto -\lambda^2 j^2/B^2$, where $\lambda$ is the Dingle factor and $j$ is the current density, in agreement with theoretical predictions. At higher magnetic fields, however, $\delta r$ becomes $B$-independent, $\delta r \propto -j^2$. While the observed change in behavior can be attributed to a crossover from overlapping to separated Landau levels, full understanding of this behavior remains a subject of future theories.