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

Abstract

This paper reports on the observation and analysis of magnetotransport phenomena in the nonlinear differential resistance ${r}_{xx}=d{V}_{xx}/dI$ of high-mobility In${}_{x}$Ga${}_{1\ensuremath{-}x}$As/InP and GaAs/Al${}_{x}$Ga${}_{1\ensuremath{-}x}$As Hall bar samples driven by direct current ${I}_{\mathrm{dc}}$. Specifically, it is observed that Shubnikov--de Haas (SdH) oscillations at large filling factors invert their phase at sufficiently large values of ${I}_{\mathrm{dc}}$. 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 ${r}_{xx}({I}_{\mathrm{dc}})$ 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.