Mikhail Otrokov1,2,Sergey Eremeev3,4,Yury Koroteev3,4,Igor Rusinov4,Alexandra Vyazovskaya4,Evgenii Petrov4,Vladimir Men’shov5,Tatyana Menshchikova4,Arthur Ernst6,Maria Blanco-Rey7,8,Andres Arnau7,1,8,Ilya Klimovskikh9,Dmitry Estyunin9,Alexander Shikin9,Ziya Aliev10,Mahammad Babanly11,Imamaddin Amiraslanov10,Nadir Abdullayev10,Vladimir Zverev12,Nazim Mamedov10,Evgueni Chulkov8,7,9
Centro de Física de Materiales1,IKERBASQUE, Basque Foundation for Science2,Institute of Strength Physics and Materials Science, Russian Academy of Sciences3,Tomsk State University4,NRC Kurchatov Institute5,Johannes Kepler University6,University of the Basque Country7,Donostia International Physics Center (DIPC)8,Saint Petersburg State University9,Institute of Physics, Azerbaijan National Academy of Sciences10,Institute of Catalysis and Inorganic Chemistry, Azerbaijan National Academy of Sciences11,Institute of Solid State Physics, Russian Academy of Sciences12
Mikhail Otrokov1,2,Sergey Eremeev3,4,Yury Koroteev3,4,Igor Rusinov4,Alexandra Vyazovskaya4,Evgenii Petrov4,Vladimir Men’shov5,Tatyana Menshchikova4,Arthur Ernst6,Maria Blanco-Rey7,8,Andres Arnau7,1,8,Ilya Klimovskikh9,Dmitry Estyunin9,Alexander Shikin9,Ziya Aliev10,Mahammad Babanly11,Imamaddin Amiraslanov10,Nadir Abdullayev10,Vladimir Zverev12,Nazim Mamedov10,Evgueni Chulkov8,7,9
Centro de Física de Materiales1,IKERBASQUE, Basque Foundation for Science2,Institute of Strength Physics and Materials Science, Russian Academy of Sciences3,Tomsk State University4,NRC Kurchatov Institute5,Johannes Kepler University6,University of the Basque Country7,Donostia International Physics Center (DIPC)8,Saint Petersburg State University9,Institute of Physics, Azerbaijan National Academy of Sciences10,Institute of Catalysis and Inorganic Chemistry, Azerbaijan National Academy of Sciences11,Institute of Solid State Physics, Russian Academy of Sciences12
Magnetic topological insulators (MTIs) are narrow gap semiconductor materials that combine non-trivial band topology and magnetic order. Unlike their nonmagnetic counterparts, MTIs may have some of the surfaces gapped due to breaking the time-reversal symmetry, which enables exotic phenomena having potential applications in spintronics. Previously, MTIs were only created by means of doping nonmagnetic TIs with 3<i>d</i> transition metal atoms, however such an approach leads to strongly inhomogeneous magnetic and electronic properties of these materials, restricting the observation of important effects to very low temperatures. Finding intrinsic MTI, i.e. a stoichiometric well-ordered compound, could be an ideal solution to these problems. Using <i>ab initio</i> calculations, we predicted the van der Waals layered compound MnBi<sub>2</sub>Te<sub>4</sub> to be the first antiferromagnetic TI (AFMTI) [1]. To date, many experimental groups confirmed the AFMTI state in MnBi<sub>2</sub>Te<sub>4</sub>, with the first observation reported in [1]. In the 2D limit, MnBi<sub>2</sub>Te<sub>4</sub> is predicted to show a unique set of thickness- and field-dependent magnetic and topological transitions, which drive it through the intrinsic quantum anomalous Hall state, its zero plateau (axion insulator), and the Chern insulator state, achieved under external magnetic field, but without Landau levels [2]. These predictions have been confirmed in recent experiments [3,4]. The discovery of the first AFMTI MnBi<sub>2</sub>Te<sub>4</sub> opens a new field that focuses on intrinsically magnetic stoichiometric compounds: several MnBi<sub>2</sub>Te<sub>4</sub>-derived MTIs were synthesized right away [5], that will be discussed in the talk along with other AFMTI candidates, predicted and observed. We will also discuss in detail the issue of the Dirac point gap in the MnBi<sub>2</sub>Te<sub>4</sub> topological surface state that caused a lot of controversy [6-9].<br/><br/>[1] M.M. Otrokov et al. Nature 576, 416 (2019)<br/>[2] M.M. Otrokov et al. Phys. Rev. Lett. 122, 107202 (2019)<br/>[3] Y. Deng et al. Science 367, 895 (2020)<br/>[4] C. Liu et al. Nature Mater. 19, 522 (2020)<br/>[5] I.I. Klimovskikh, M.M. Otrokov et al. npj Quantum Mater. 5, 54 (2020)<br/>[6] Y. Hao et al. Phys. Rev. X 9, 041038 (2019)<br/>[7] H. Li et al. Phys. Rev. X 9, 041039 (2019)<br/>[8] A.M. Shikin et al. Phys. Rev. B 104, 115168 (2021)<br/>[9] M. Garnica, M. M. Otrokov et al. arXiv:2109.01615