Observation of the quantized Hall insulator in the quantum critical regime of the two-dimensional electron gas

TL;DR

This study demonstrates that the Hall resistance in a two-dimensional electron gas becomes quantized at h/e^2 near the critical point of the plateau-insulator transition at low temperatures, revealing a quantized Hall insulator phase.

Contribution

The paper provides experimental evidence of a quantized Hall insulator in the quantum critical regime, using high-field magnetotransport data and universal scaling analysis.

Findings

Hall resistance quantizes at h/e^2 near critical filling fraction at low T

Hall resistance diverges for filling fractions below critical as T approaches zero

Universal scaling functions describe the behavior of R_H in the critical regime

Abstract

We have investigated the Hall resistance $R_H$ near the plateau-insulator transition of a two-dimensional electron gas in the quantum critical regime. High-field magnetotransport data taken on a low-mobility InGaAs/InP heterostructure with the plateau-insulator transition at a critical field $B_c$ of 17.2 T show that the Hall resistance $R_H$ is quantized at $h/e^2$ near the critical filling fraction ($\nu_c$ = 0.55) when $T \to 0$. By making use of universal scaling functions extracted from the magnetotransport data we show that $R_H$ in the insulating phase in the limit $T \to 0$ is quantized at $h/e^2$ for all values of the scaling parameter $\Delta\nu /(T/T_0)^\kappa$ with $\Delta\nu = \nu - \nu_c$. However, as a function of $\Delta\nu $ (or magnetic field) the Hall resistance diverges in the limit $T \to 0$ for all values $\nu < \nu_c$.