Zero-field quantum anomalous Hall metrology as a step towards a universal quantum standard unit system

TL;DR

This paper reports a highly precise measurement of the quantized anomalous Hall resistance in a ferromagnetic topological insulator at zero magnetic field, advancing toward a universal quantum resistance standard.

Contribution

It provides the most precise measurement to date of zero-field quantum anomalous Hall resistance, establishing a new upper limit for deviations from the von-Klitzing constant.

Findings

Resistance deviation limit of 0.26 ± 0.22 ppm from R_K

First comprehensive uncertainty budget for zero-field QAH resistance

Progress towards a universal quantum resistance standard

Abstract

In the quantum anomalous Hall effect, the edge states of a ferromagnetically doped topological insulator exhibit quantized Hall resistance and dissipationless transport at zero magnetic field. Up to now, however, the resistance was experimentally assessed with standard transport measurement techniques which are difficult to trace to the von-Klitzing constant R$_K$ with high precision. Here, we present a metrologically comprehensive measurement, including a full uncertainty budget, of the resistance quantization of V-doped (Bi,Sb)$_2$Te$_3$ devices without external magnetic field. We established as a new upper limit for a potential deviation of the quantized anomalous Hall resistance from RK a value of 0.26 +- 0.22 ppm, the smallest and most precise value reported to date. This provides another major step towards realization of the zero-field quantum resistance standard which in combination with Josephson effect will provide the universal quantum units standard in the future.