Controllable quantum point junction on the surface of an antiferromagnetic topological insulator

Nicodemos Varnava,Justin H Wilson,J H Pixley,David Vanderbilt

doi:10.1038/s41467-021-24276-5

Abstract

Engineering and manipulation of unidirectional channels has been achieved in quantum Hall systems, leading to the construction of electron interferometers and proposals for low-power electronics and quantum information science applications. However, to fully control the mixing and interference of edge-state wave functions, one needs stable and tunable junctions. Encouraged by recent material candidates, here we propose to achieve this using an antiferromagnetic topological insulator that supports two distinct types of gapless unidirectional channels, one from antiferromagnetic domain walls and the other from single-height steps. Their distinct geometric nature allows them to intersect robustly to form quantum point junctions, which then enables their control by magnetic and electrostatic local probes. We show how the existence of stable and tunable junctions, the intrinsic magnetism and the potential for higher-temperature performance make antiferromagnetic topological insulators a promising platform for electron quantum optics and microelectronic applications.

Highlights

Engineering and manipulation of unidirectional channels has been achieved in quantum Hall systems, leading to the construction of electron interferometers and proposals for low-power electronics and quantum information science applications
The MnBi2Te4 family of materials belongs to a class of 3D materials that have been variously described as intrinsic magnetic topological insulators[12,15,16,17], axion insulators[18,19,20] and second-order topological insulators[21,22,23]
This class of materials was introduced theoretically by Mong and Moore[26] and has recently become the focus of intense research with various candidates such as MnBi2Te427, MnBi4Te728, EuIn2As229 and NpBi30 appearing in the literature. Motivated by these recent developments and the fact that there is in principle no reason why both the bulk and surface gaps could not be on the order of hundreds of meV, allowing for potential high temperature device operation for certain applications, we propose and explore the properties of a robust and controllable quantum point junction (QPJ) on the surface of an AFM topological insulators (TI)

Summary

Introduction

Engineering and manipulation of unidirectional channels has been achieved in quantum Hall systems, leading to the construction of electron interferometers and proposals for low-power electronics and quantum information science applications. The discovery of the quantum anomalous Hall effect in twisted bilayer graphene[10,11], MnBi2Te412 and MnBi2Te4/Bi2Te3 heterostructures[13] holds promise for the realization of topologically protected chiral channels at higher temperatures, due in part to the absence of magnetic-impurity disorder[14] In their bulk version, the MnBi2Te4 family of materials belongs to a class of 3D materials that have been variously described as intrinsic magnetic topological insulators[12,15,16,17], axion insulators[18,19,20] and second-order topological insulators[21,22,23]. They exhibit a half-quantized surface anomalous Hall conductivity, i.e., an odd integer times e2/

Methods

Results

Conclusion