Pressure-Induced Topological and Structural Phase Transitions in an Antiferromagnetic Topological Insulator*
Cuiying Pei, Yunyouyou Xia, Jiazhen Wu, Yi Zhao, Lingling Gao, Tianping Ying, Bo Gao, Nana Li, Wenge Yang, Dongzhou Zhang, Huiyang Gou, Yulin Chen, Hideo Hosono, Gang Li, Yanpeng Qi
Abstract
Recently, natural van der Waals heterostructures of (MnBi 2 Te 4 ) m (Bi 2 Te 3 ) n have been theoretically predicted and experimentally shown to host tunable magnetic properties and topologically nontrivial surface states. We systematically investigate both the structural and electronic responses of MnBi 2 Te 4 and MnBi 4 Te 7 to external pressure. In addition to the suppression of antiferromagnetic order, MnBi 2 Te 4 is found to undergo a metal–semiconductor–metal transition upon compression. The resistivity of MnBi 4 Te 7 changes dramatically under high pressure and a non-monotonic evolution of ρ ( T ) is observed. The nontrivial topology is proved to persist before the structural phase transition observed in the high-pressure regime. We find that the bulk and surface states respond differently to pressure, which is consistent with the non-monotonic change of the resistivity. Interestingly, a pressure-induced amorphous state is observed in MnBi 2 Te 4 , while two high-pressure phase transitions are revealed in MnBi 4 Te 7 . Our combined theoretical and experimental research establishes MnBi 2 Te 4 and MnBi 4 Te 7 as highly tunable magnetic topological insulators, in which phase transitions and new ground states emerge upon compression.