The Quantized Hall Insulator: A New Insulator in Two-Dimensions

TL;DR

This paper reports the discovery of a new type of insulator in two-dimensional electron systems, called the quantized Hall insulator, characterized by a quantized Hall resistance despite being insulating, extending the quantum Hall effect series.

Contribution

The paper experimentally demonstrates the existence of a quantized Hall insulator, a novel insulator state with quantized Hall resistance, which terminates the quantum Hall effect series in 2D systems.

Findings

Existence of a quantized Hall insulator with quantized Hall resistance

The insulator terminates the quantum Hall effect series in 2D systems

Preceding insulating state at low magnetic field is also of the Hall insulator type

Abstract

Quite generally, an insulator is theoretically defined by a vanishing conductivity tensor at the absolute zero of temperature. In classical insulators, such as band insulators, vanishing conductivities lead to diverging resistivities. In other insulators, in particular when a high magnetic field (B) is added, it is possible that while the magneto-resistance diverges, the Hall resistance remains finite, which is known as a Hall insulator. In this letter we demonstrate experimentally the existence of another, more exotic, insulator. This insulator, which terminates the quantum Hall effect series in a two-dimensional electron system, is characterized by a Hall resistance which is approximately quantized in the quantum unit of resistance h/e^2. This insulator is termed a quantized Hall insulator. In addition we show that for the same sample, the insulating state preceding the QHE series, at low-B, is of the HI kind.