Prediction and observation of the first antiferromagnetic topological insulator
Abstract
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 a number of exotic phenomena having potential applications in spintronics. So far, MTIs have only been created by means of doping nonmagnetic TIs with 3d transition metal elements, 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 magnetic compound, could be an ideal solution to these problems, but no such material was observed to date. Here, using density functional theory we predict and further confirm by means of structural, transport, magnetic, angle- and spin-resolved photoemission spectroscopy measurements the realization of the antiferromagnetic (AFM) TI phase, that is hosted by the van der Waals layered compound MnBiTe. An interlayer AFM ordering makes MnBiTe invariant with respect to the combination of the time-reversal () and primitive-lattice translation () symmetries, , giving rise to the topological classification of AFM insulators. We find for MnBiTe, which confirms its topologically nontrivial nature. The -breaking (0001) surface of MnBiTe exhibits a giant bandgap in the topological surface state as evidenced by ab initio calculations and photoemission measurements. These results culminate almost a decade-long search of an AFMTI, predicted in 2010. Furthermore, MnBiTe is the first intrinsic magnetic TI realized experimentally.
Keywords
Cite
@article{arxiv.1809.07389,
title = {Prediction and observation of the first antiferromagnetic topological insulator},
author = {Mikhail M. Otrokov and Ilya I. Klimovskikh and Hendrik Bentmann and Dmitry Estyunin and Alexander Zeugner and Ziya S. Aliev and Sebastian Gass and Anja U. B. Wolter and Alexandra V. Koroleva and Alexander M. Shikin and María Blanco-Rey and Martin Hoffmann and Igor P. Rusinov and Alexandra Yu. Vyazovskaya and Sergey V. Eremeev and Yury M. Koroteev and V. M. Kuznetsov and F. Freyse and J. Sánchez-Barriga and Imamaddin R. Amiraslanov and Mahammad B. Babanly and Nazim T. Mamedov and Nadir A. Abdullayev and Vladimir N. Zverev and Alexey Alfonsov and Vladislav Kataev and Bernd Büchner and Eike F. Schwier and Shiv Kumar and Akio Kimura and Luca Petaccia and Giovanni Di Santo and Raphael C. Vidal and Sonja Schatz and Katharina Kißner and M. Ünzelmann and Chul-Hee Min and Simon K. Moser and Thiago R. F. Peixoto and Friedrich Reinert and Arthur Ernst and Pedro M. Echenique and Anna Isaeva and Evgueni V. Chulkov},
journal= {arXiv preprint arXiv:1809.07389},
year = {2025}
}