Non-linear magnetotransport phenomena in high-mobility two-dimensional electrons in InGaAs/InP and GaAs/AlGaAs

TL;DR

This study investigates nonlinear magnetotransport phenomena in high-mobility 2D electron systems, revealing phase-inverted SdH oscillations, diamond-shaped patterns in the quantum Hall regime, and a zero current anomaly, with implications for understanding electron heating and spin gaps.

Contribution

It provides the first detailed analysis of nonlinear differential resistance features, including phase-inverted SdH oscillations and transport diamonds, in high-mobility 2D electron systems, linking them to intrinsic properties.

Findings

Phase-inverted SdH oscillations at large currents

Diamond-shaped patterns in quantum Hall regime

Zero Current Anomaly dependent on temperature

Abstract

This paper reports on the observation and analysis of magnetotransport phenomena in the nonlinear differential resistance $r_{xx}=dV_{xx}/dI$ of high-mobility InGaAs/InP and GaAs/AlGaAs Hall bar samples driven by direct current, $\Idc$. Specifically, it is observed that Shubnikov -de Haas (SdH) oscillations at large filling factors invert their phase at sufficiently large values of $\Idc$. This phase inversion is explained as being due to an electron heating effect. In the quantum Hall effect regime the $r_{xx}$ oscillations transform into diamond-shaped patterns with different slopes corresponding to odd and even filling factors. The diamond-shaped features at odd filling factors can be used as a probe to determine spin energy gaps. A Zero Current Anomaly (ZCA) which manifests itself as a narrow dip in the $r_{xx}(\Idc)$ characteristics at zero current, is also observed. The ZCA effect strongly depends upon temperature, vanishing above 1 K while the transport diamonds persist to higher temperatures. The transport diamonds and ZCA are fully reproduced in a higher mobility GaAs/AlGaAs Hall bar structure confirming that these phenomena reflect intrinsic properties of two-dimensional systems.