Interlayer coupling modulated tunable magnetic states in superlattice MnBi2Te4 (Bi2Te3)n topological insulators

The intrinsic superlattice magnetic topological insulators of MnBi2Te4(Bi2Te3)n (n=0,1,2...) provides a promising material platform for the realization of diverse exotic topological quantum states, such as quantum anomalous Hall effect and axion-insulator state. All these quantum states are sensitively dependent on the complex interplay and intertwinement of their band topology, magnetism, and defective structural details. Here, we report a comprehensive real-space investigation on the magnetic ordering states of MnBi2Te4(Bi2Te3)n using cryogenic magnetic force microscopy. The MnBi2Te4(Bi2Te3)n crystals exhibit a distinctive magnetic evolution from A-type antiferromagnetic to ferromagnetic states via the increased Bi2Te3 intercalation layers. The magnetic field- and temperature-dependent phase evolution behaviors of MnBi6Te10 and MnBi8Te13 are comparatively investigated to obtain the complete H-T phase diagrams. The combination impact of the intrinsic and defect-mediated interlayer coupling on their magnetic states were further discussed. Our results pave a possible way to realize more exotic quantum states via the tunable magnetic configurations in the artificial-stacking MnBi2Te4(Bi2Te3)n multilayers.