Thickness-dependent electronic behavior of MBE grown MnBi₂Te₄

Quantum anomalous Hall insulator is seen as a promising candidate for the application of spintronics due to their symmetry-protected dissipationless edge states. Recently, van de Waals layered magnetic topological insulator, MnBi₂Te₄, was reported to show the anomalous hall effect at a temperature that is orders of magnitude higher than the previous magnetically doped topological insulators. However, its electronic structure, especially its surface state gaps, is still under debate. In this study, we report a controlled growth of MnBi₂Te₄ thin films using molecular beam epitaxy, and we revealed their thickness-dependent electronic behavior using scanning tunneling microscopy/spectroscopy. Our experimental observation is further supported by the theoretical calculation. This study provides insight into the intrinsic property of MnBi₂Te₄ and sheds light on the spintronics application based on the topological insulator platform.