Institute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL),
CH-1015 Lausanne, Switzerland
Email: oleg.yazyev@epfl.ch

报告摘要：
A large number of different topological electronic phases that can be realized in materials have been predicted recently. We have developed a first-principles methodology for identifying materials hosting various topological phases among known compounds. In my talk, I will discuss various aspects of performing such high-throughput screening relying on the Z2Pack methodology [1] and present first predictions successfully confirmed by experiments. In particular, a new Z2 topological insulator was theoretically predicted and experimentally confirmed in the β-phase of quasi-one-dimensional bismuth iodide Bi4I4 [2]. The electronic structure of β-Bi4I4, characterized by Z2 invariants (1;110), is in proximity of both the weak TI phase (0;001) and the trivial insulator phase (0;000). We further predicted robust type-II Weyl semimetal phase in transition metal diphosphides MoP2 and WP2 characterized by very large momentum-space separation between Weyl points of opposite chirality [3]. Recent experimental investigation of WP2 revealed that this material shows record magnitudes of magnetoresistance combined with very high conductivity and residual resistivity ratio [4] as well as some other fascinating properties. We further show that transverse magnetoresistance and its anisotropy can be understood by analyzing the Fermi surface morphology [5].
 
This work was supported by the Swiss NSF, ERC project “TopoMat” and NCCR-MARVEL.
1.  D. Gresch, G. Autès, O. V. Yazyev, M. Troyer, D. Vanderbilt, B. A. Bernevig and A. A. Soluyanov, Phys. Rev. B 95, 075146 (2017)
2. G. Autès, A. Isaeva, L. Moreschini, J. C. Johannsen, A. Pisoni, R. Mori, W. Zhang, T. G. Filatova, A. N. Kuznetsov, L. Forró, W. Van den Broek, Y. Kim, K. S. Kim, A. Lanzara, J. D. Denlinger, E. Rotenberg, A. Bostwick, M. Grioni, and O. V. Yazyev, Nature Materials 15, 154 (2016).
3.  G. Autès, D. Gresch, M. Troyer, A. A. Soluyanov and O. V. Yazyev, Phys. Rev. Lett. 117, 066402 (2016).
4. N. Kumar, Y. Sun, K. Manna, V. Suess, I. Leermakers, O. Young, T. Foerster, M. Schmidt, B. Yan, U. Zeitler, C. Felser, and C. Shekhar, Nat. Commun. 8, 1642 (2017).
5. S. N. Zhang, Q. S. Wu, Y. Liu, and O. V. Yazyev, in preparation.

报告人简介：
Prof. Oleg Yazyev was born in Simferopol, Crimean peninsula. He obtained his degree in chemistry from Moscow State University in 2003. He then joined Ecole Polytechnique Fédérale de Lausanne (EPFL) completing his PhD thesis in 2007. Next two years he has spent as a postdoctoral fellow at the Institute of Theoretical Physics (ITP) and the Institute for Numerical Research in the Physics of Materials (IRRMA) of the same institution. In 2009-2011 he was a postdoctoral fellow at the Department of Physics of the University of California, Berkeley and the Lawrence Berkeley National Laboratory. In September 2011 he started an independent research group supported by the Swiss National Science Foundation professorship grant. In 2012 he was awarded an ERC Starting grant. His current research focuses on the theoretical and computational physics of two-dimensional and topological materials with strong emphasis on their prospective technological applications.

邀请人：翁红明
电话：82649941