Influences of the dissipative topological edge state on quantized transport in MnBi2Te4

TL;DR

This study reveals that in MnBi2Te4, dissipative topological edge states persist even when quantized transport breaks down, highlighting their diffusive nature and impact on device performance.

Contribution

It demonstrates that quantization breakdown is not due to edge state disappearance but due to their dissipative, diffusive character in MnBi2Te4.

Findings

Topological edge states exist during quantization breakdown.

Dissipative edge states cause overlapping with bulk states.

Diffusive edge states impact practical device applications.

Abstract

The beauty of quantum Hall (QH) effect is the metrological precision of Hall resistance quantization that originates from the topological edge states. Understanding the factors that lead to quantization breakdown not only provides important insights on the nature of the topological protection of these edge states, but is beneficial for device applications involving such quantized transport. In this work, we combine conventional transport and real space conductivity mapping to investigate whether the quantization breakdown is tied to the disappearance of edge state in the hotly studied MnBi2Te4 system. Our experimental results unambiguously show that topological edge state does exist when quantization breakdown occurs. Such edge state is dissipative in nature and could lead to a quantization breakdown due to its diffusive character causing overlapping with bulk and other edge states in real devices. Our findings bring attentions to issues that are generally inaccessible in the transport study of QH, but can play important roles in practical measurements and device applications.