Pressure-Induced Topological and Structural Phase Transitions in an Antiferromagnetic Topological Insulator

• Published in: Chinese physics letters Vol. 37; no. 6; p. 66401
• Main Authors: Pei, Cuiying, Xia, Yunyouyou, Wu, Jiazhen, Zhao, Yi, Gao, Lingling, Ying, Tianping, Gao, Bo, Li, Nana, Yang, Wenge, Zhang, Dongzhou, Gou, Huiyang, Chen, Yulin, Hosono, Hideo, Li, Gang, Qi, Yanpeng
• Format: Journal Article
• Language: English
• Published: 01.06.2020
• ISSN: 0256-307X; 1741-3540
• DOI: 10.1088/0256-307X/37/6/066401

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.