The intrinsic magnetic topological insulator MnBi₂Te₄ has attracted much attention due to its special magnetic and topological properties. To date, most reports have focused on bulk or flake samples. For material integration and device applications, the epitaxial growth of MnBi₂Te₄ film in nanoscale is more important but challenging. Here, we report the growth of self-regulated MnBi₂Te₄ films by the molecular beam epitaxy. By tuning the substrate temperature to the optimal temperature for the growth surface, the stoichiometry of MnBi₂Te₄ becomes sensitive to the Mn/Bi flux ratio. Excessive and deficient Mn resulted in the formation of a MnTe and Bi₂Te₃ phase, respectively. The magnetic measurement of the 7 SL MnBi₂Te₄ film probed by the superconducting quantum interference device (SQUID) shows that the antiferromagnetic order occurring at the Néel temperature 22 K is accompanied by an anomalous magnetic hysteresis loop along the c-axis. The band structure measured by angle-resolved photoemission spectroscopy (ARPES) at 80 K reveals a Dirac-like surface state, which indicates that MnBi₂Te₄ has topological insulator properties in the paramagnetic phase. Our work demonstrates the key growth parameters for the design and optimization of the synthesis of nanoscale MnBi₂Te₄ films, which are of great significance for fundamental research and device applications involving antiferromagnetic topological insulators.

A spectroscopic imaging-scanning tunneling microscope (SI-STM) allows for the atomic scale visualization of the surface electronic and magnetic structure of novel quantum materials with a high energy resolution. To achieve the optimal performance, a low vibration facility is required. Here, we describe the design and performance of an ultrahigh vacuum STM system supported by a hybrid vibration isolation system that consists of a pneumatic passive and a piezoelectric active vibration isolation stage. We present the detailed vibrational noise analysis of the hybrid vibration isolation system, which shows that the vibration level can be suppressed below 10−8 m/sec/√Hz for most frequencies up to 100 Hz. Combined with a rigid STM design, vibrational noise can be successfully removed from the tunneling current. We demonstrate the performance of our STM system by taking high resolution spectroscopic maps and topographic images on several quantum materials. Our results establish a new strategy to achieve an effective vibration isolation system for high-resolution STM and other scanning probe microscopies to investigate the nanoscale quantum phenomena.