Atomistic Control in Molecular Beam Epitaxy Growth of Intrinsic Magnetic Topological Insulator MnBi2Te4

TL;DR

This paper demonstrates atomic-level control in growing high-quality MnBi2Te4 magnetic topological insulator films via molecular beam epitaxy, revealing insights into growth dynamics and substrate interactions crucial for quantum applications.

Contribution

It provides a detailed analysis of the epitaxial growth process of MnBi2Te4, including free energy landscape and chemical potential, advancing understanding of MBE growth of topological insulators.

Findings

Optimized layer-by-layer growth improves film quality.

Identified the free energy landscape for epitaxial relationships.

Determined chemical potential and Dirac point at various thicknesses.

Abstract

Intrinsic magnetic topological insulators have emerged as a promising platform to study the interplay between topological surface states and ferromagnetism. This unique interplay can give rise to a variety of exotic quantum phenomena, including the quantum anomalous Hall effect and axion insulating states. Here, utilizing molecular beam epitaxy (MBE), we present a comprehensive study of the growth of high-quality MnBi2Te4 thin films on Si (111), epitaxial graphene, and highly ordered pyrolytic graphite substrates. By combining a suite of in-situ characterization techniques, we obtain critical insights into the atomic-level control of MnBi2Te4 epitaxial growth. First, we extract the free energy landscape for the epitaxial relationship as a function of the in-plane angular distribution. Then, by employing an optimized layer-by-layer growth, we determine the chemical potential and Dirac point of the thin film at different thicknesses. Overall, these results establish a foundation for understanding the growth dynamics of MnBi2Te4 and pave the way for the future applications of MBE in emerging topological quantum materials.