Epitaxial Growth and Magnetic Ordering of Antiferromagnetic Topological Insulator  MnBi₂Te₄

MnBi₂Te₄ (MBT) is a prototypical antiferromagnetic topological insulator (AFMTI), that offers a platform to study emergent quantum phases where time-reversal symmetry is intrinsically broken. The compound consists of layered Van der Waals stacks of Te–Bi–Te–Mn–Te–Bi–Te septuple layers where the Mn sublattice introduces long-range magnetic order into a topological framework. 

Here we report the molecular beam epitaxy growth of MBT thin films epitaxially grown on insulating Al₂O₃ (0001) substrates with a Bi₂Te₃ buffer layer. Streaky reflection high-energy electron diffraction (RHEED) patterns during deposition and X-ray diffraction measurements confirm smooth surfaces, high crystallinity, and well-defined layered ordering. Low-temperature magnetization measurements at T=3.5K exhibit a primarily linear field dependence with a change in slope consistent with a spin-flop transition reported in bulk MBT single crystals.

Low-temperature magnetotransport measurements further reveal clear signatures of antiferromagnetic ordering, spin-flop behavior, and weak anti-localization effects characteristic of topological surface states. Together, these results confirm that epitaxial MBT thin films preserve intrinsic AFM order while exhibiting tunable spin configurations under applied field. This work establishes a pathway for exploring the interplay between magnetism and topology in MBT-based heterostructures and for developing AFMTI platforms relevant to next-generation quantum and spintronic devices.