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Topological Transitions Induced by Antiferromagnetism in a Thin-Film Topological Insulator



Qing Lin He, Gen Yin, Luyan Yu, Alexander Grutter, Lei Pan, Chui-Zhen Chen, Xiaoyu Che, Guoqiang Yu, Bin Zhang, Qiming Shao, Alexander L. Stern, Brian Casas, Jing Xia, Xiaodong Han, Brian Kirby, Roger K. Lake, K. T. Law, Kang L. Wang


Ferromagnetism in topological insulators (TIs) opens a topologically non-trivial exchange band gap, providing an exciting platform for manipulating the topological order through external magnetic field. Here, we experimentally show that the surface of an antiferromagnetic thin film can independently control the topological order of the top and the bottom surface states in a TI thin film through proximity couplings. During magnetization reversal, two intermediate spin configurations stem from unsynchronized switchings of the top and the bottom antiferromagnetic layers. These configurations are shown to induce topological phases with secondary Chern numbers, introducing two counter-propagating chiral edge modes inside the exchange gap. This change in the number of transport channels induces antisymmetric magneto resistance spikes during the scan of the external magnetic field. With the help of the high ordering temperature of the CrSb layers, signatures of the induced topological transition persists in transport measurements up to temperatures of approximately 90 K.
Physical Review Letters


Topological Insulator, Magnetism, Superlattice, Film, Neutron Reflectometry


He, Q. , Yin, G. , Yu, L. , Grutter, A. , Pan, L. , Chen, C. , Che, X. , Yu, G. , Zhang, B. , Shao, Q. , Stern, A. , Casas, B. , Xia, J. , Han, X. , Kirby, B. , Lake, R. , Law, K. and Wang, K. (2018), Topological Transitions Induced by Antiferromagnetism in a Thin-Film Topological Insulator, Physical Review Letters, [online], (Accessed April 17, 2024)
Created August 28, 2018, Updated October 12, 2021