第11回物理工学科教室談話会[Prof. Oleg V. Yazyev・1/13(火)14:00～]

講　師：Prof. Oleg V. Yazyev
所　属：1 Institute of Physics, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
　　　　2 National Centre for Computational Design and Discovery of Novel Materials MARVEL, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
題　目：In silico discovery of novel topological materials
日　時：2026 年 1 月 13 日(火)14:00～
Date and Time： January 13th, 2026 (Tuesday) 14:00-
場　所：工 6 号館 3 階セミナー室 A
Place：Seminar Room A, 3rd floor, Engineering Bldg. 6

Abstract：
In my talk, I will focus on our recent efforts directed towards the search of novel topological materials. A large number of diverse topological electronic phases that can be realized in materials have been predicted recently. We have developed a high-throughput computational screening methodology for identifying materials hosting various topological phases among known materials. The entire dataset of results obtained using this high-throughput search is now publicly available via the Materials Cloud platform [1]. Several predictions resulting from this search that have been successfully confirmed by experiments. 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 experiments on WP2 revealed record magnitudes of magnetoresistance combined with very high conductivity and residual resistivity ratio [4], and many other extraordinary properties. I will discuss in detail the physical mechanism underlying magnetotransport in WP2 as well as in other trivial and topological semimetals [5].
[1] G. Autès, Q. S. Wu, N. Mounet, and O. V. Yazyev, “TopoMat: a database of high-throughput first-principles calculations of topological materials”, https://www.materialscloud.org/discover/topomat
[2] G. Autès et al., Nature Mater. 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 et al., Nature Commun. 8, 1642 (2017).
[5] S. N. Zhang, Q. S. Wu, Y. Liu and O. V. Yazyev, Phys. Rev. B 99, 035142 (2019).

紹介教員：村上 修一 教授（物理工学専攻）、渡辺 悠樹 准教授（物理工学専攻）