Exploring the Epitaxial Growth Kinetics and Anomalous Hall Effect in Magnetic Topological Insulator MnBi₂Te₄ Films.

Abstract

The discovery of MnBi₂Te₄-based intrinsic magnetic topological insulators has fueled tremendous interest in condensed matter physics, owing to their potential as an ideal platform for exploring the quantum anomalous Hall effect and other magnetism-topology interactions. However, the fabrication of single-phase MnBi₂Te₄ films remains a common challenge in the research field. Herein, we present an effective and simple approach for fabricating high-quality, near-stoichiometric MnBi₂Te₄ films by directly matching the growth rates of intermediate Bi₂Te₃ and MnTe. Through systematic experimental studies and thermodynamic calculations, we demonstrate that binary phases of Bi₂Te₃ and MnTe are easily formed during film growth, and the reaction of Bi₂Te₃ + MnTe → MnBi₂Te₄ represents the rate-limiting step among all possible reaction paths, which could result in the presence of Bi₂Te₃ and MnTe impurity phases in the grown MnBi₂Te₄ films. Moreover, Bi₂Te₃ and MnTe impurities introduce negative and positive anomalous Hall (AH) components, respectively, in the AH signals of MnBi₂Te₄ films. Our work suggests that further manipulation of growth parameters should be the essential route for fabricating phase-pure MnBi₂Te₄ films.