Quantum anomalous Hall effect for metrology

TL;DR

This paper reviews the quantum anomalous Hall effect in magnetic topological insulators, highlighting its potential for quantum electrical metrology and discussing material growth, characterization, and challenges in establishing resistance standards.

Contribution

It provides a comprehensive overview of QAHE, discusses progress in material development, and proposes strategies for implementing QAHE-based resistance standards in metrology.

Findings

QAHE can enable zero-field quantum resistance standards

Material improvements are crucial for robust resistance quantization

Guidelines for QAHE resistance metrology are proposed

Abstract

The quantum anomalous Hall effect (QAHE) in magnetic topological insulators offers great potential to revolutionize quantum electrical metrology by establishing primary resistance standards operating at zero external magnetic field and realizing a universal "quantum electrical metrology toolbox" that can perform quantum resistance, voltage and current metrology in a single instrument. To realize such promise, significant progress is still required to address materials and metrological challenges -- among which, one main challenge is to make the bulk of the topological insulator sufficiently insulating to improve the robustness of resistance quantization. In this Perspective, we present an overview of the QAHE; discuss the aspects of topological material growth and characterization; and present a path towards an QAHE resistance standard realized in magnetically doped (Bi,Sb)$_2$Te$_3$ systems. We also present guidelines and methodologies for QAHE resistance metrology, its main limitations and challenges as well as modern strategies to overcome them.