Exploring the Epitaxial Growth Kinetics and Anomalous Hall Effect in Magnetic Topological Insulator MnBi 2 Te 4 Films.

The discovery of MnBi 2 Te 4 -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 MnBi 2 Te 4 films remains a common challenge in the research field. Herein, we present an effective and simple approach for fabricating high-quality, near-stoichiometric MnBi 2 Te 4 films by directly matching the growth rates of intermediate Bi 2 Te 3 and MnTe. Through systematic experimental studies and thermodynamic calculations, we demonstrate that binary phases of Bi 2 Te 3 and MnTe are easily formed during film growth, and the reaction of Bi 2 Te 3 + MnTe → MnBi 2 Te 4 represents the rate-limiting step among all possible reaction paths, which could result in the presence of Bi 2 Te 3 and MnTe impurity phases in the grown MnBi 2 Te 4 films. Moreover, Bi 2 Te 3 and MnTe impurities introduce negative and positive anomalous Hall (AH) components, respectively, in the AH signals of MnBi 2 Te 4 films. Our work suggests that further manipulation of growth parameters should be the essential route for fabricating phase-pure MnBi 2 Te 4 films.