Demonstration of Dissipative Quasihelical Edge Transport in Quantum Anomalous Hall Insulators

TL;DR

This study investigates the dissipation mechanisms in quantum anomalous Hall insulators, revealing how interactions between bulk, chiral, and non-chiral edge states influence transport properties, crucial for realizing dissipationless quantum devices.

Contribution

It demonstrates the switching of dissipation mechanisms between non-chiral edge states and residual bulk states in magnetic topological insulators under different magnetic fields.

Findings

Dissipation in QAH insulators can originate from non-chiral edge states or residual bulk states.

The dissipation mechanism depends on the magnetic field regime.

Interactions between bulk, chiral, and non-chiral edge states are characterized.

Abstract

Doping a topological insulator (TI) film with transition metal ions can break its time-reversal symmetry and lead to the realization of the quantum anomalous Hall (QAH) effect. Prior studies have shown that the longitudinal resistance of the QAH samples usually does not vanish when the Hall resistance shows a good quantization. This has been interpreted as a result of the presence of possible dissipative conducting channels in magnetic TI samples. By studying the temperature- and magnetic field-dependence of the magnetoresistance of a magnetic TI sandwich heterostructure device, we demonstrate that the predominant dissipation mechanism in thick QAH insulators can switch between non-chiral edge states and residual bulk states in different magnetic field regimes. The interactions between bulk states, chiral edge states, and non-chiral edge states are also investigated. Our study provides a way to distinguish between the dissipation arising from the residual bulk states and non-chiral edge states, which is crucial for achieving true dissipationless transport in QAH insulators and for providing deeper insights into QAH-related phenomena.