Chromium-Doped Bismuth Antimony Telluride for Future Quantum Hall Resistance Standards

TL;DR

This paper explores magnetically doped topological insulators as a promising material for quantum Hall resistance standards that operate at low or zero magnetic fields, potentially revolutionizing electrical metrology.

Contribution

It presents precision measurements of the quantized resistance in Cr-doped (BixSb1-x)2Te3, demonstrating its potential as a new quantum resistance standard without strong magnetic fields.

Findings

Achieved quantized resistance plateau in Cr-doped (BixSb1-x)2Te3

Compared MTI-based standards with graphene-based standards

Showed potential for zero-field quantum resistance measurements

Abstract

Since 2017, epitaxial graphene has been the base material for the US national standard for resistance. A future avenue of research within electrical metrology is to remove the need for strong magnetic fields, as is currently the case for devices exhibiting the quantum Hall effect. The quantum Hall effect is just one of many research endeavours that revolve around recent quantum physical phenomena like composite fermions, charge density waves, and topological properties [1-2]. New materials, like magnetically doped topological insulators (MTIs), offer access to the quantum anomalous Hall effect, which in its ideal form, could become a future resistance standard needing only a small permanent magnet to activate a quantized resistance value [3-5]. Furthermore, these devices could operate at zero-field for measurements, making the dissemination of the ohm more economical and portable. Here we present results on precision measurements of the h/e2 quantized plateau of Cr-Doped (BixSb1-x)2Te3 and give them context by comparing them to modern graphene-based resistance standards. Ultimately, MTI-based devices could be combined in a single system with magnetic-field-averse Josephson voltage standards to obtain an alternative quantum current standard.