Quantum anomalous Hall multilayers grown by molecular beam epitaxy

TL;DR

This paper reports the first experimental realization of quantum anomalous Hall multilayers grown by molecular beam epitaxy, demonstrating high Chern number QAH insulators with potential for exotic topological phases and low-energy electronics.

Contribution

It introduces the fabrication and characterization of QAH multilayers composed of magnetically doped topological insulators and normal insulators, achieving quantized Hall resistance indicative of high Chern number phases.

Findings

Successful growth of QAH multilayers via molecular beam epitaxy.

Observation of quantized Hall resistance proportional to the number of magnetic layers.

Potential to engineer exotic topological phases like magnetic Weyl semimetals.

Abstract

Quantum anomalous Hall (QAH) effect is a quantum Hall effect that occurs without the need of external magnetic field. A system composed of multiple parallel QAH layers is an effective high Chern number QAH insulator and the key to the applications of the dissipationless chiral edge channels in low energy consumption electronics. Such a QAH multilayer can also be engineered into other exotic topological phases such as a magnetic Weyl semimetal with only one pair of Weyl points. This work reports the first experimental realization of QAH multilayers in the superlattices composed of magnetically doped (Bi,Sb)$_2$Te$_3$ topological insulator and CdSe normal insulator layers grown by molecular beam epitaxy. The obtained multilayer samples show quantized Hall resistance $h/Ne$$^2$, where $h$ is the Planck's constant, $e$ is the elementary charge and $N$ is the number of the magnetic topological insulator layers, resembling a high Chern number QAH insulator.