séminaire DQMP - Computational search of novel topological materials

04.12.2018 13:00 – 14:30

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 approach is based on first-principles calculations in combination with the Z2Pack methodology for evaluating topological invariants [1]. The entire dataset of results obtained using this high-throughput search is publically available via the Materials Cloud platform [2]. In the rest of my talk, I will focus on 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 [3]. 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 [4]. Recent experimental investigation of WP2 revealed that this material shows record magnitudes of magnetoresistance combined with very high conductivity and residual resistivity ratio [5] as well as some other fascinating properties. We further show that the extremely large non-saturating transverse magnetoresistance and its anisotropy observed in WP2 can be fully understood within the semiclassical approximation [6]. Moreover, we argue that the Fermi-arc surface states, the hallmark of the topological band degeneracies, are actually rather common in materials lacking inversion or time-reversal symmetry. We support this statement by identifying the Fermi-arc surface resonances at the Fermi level in a material as simple and common as ferromagnetic iron [7].

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, 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
3. 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).
4. G. Autès, D. Gresch, M. Troyer, A. A. Soluyanov and O. V. Yazyev, Phys. Rev. Lett. 117, 066402 (2016).
5. 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, Nature Commun. 8, 1642 (2017).
6. S. N. Zhang, Q. S. Wu, Y. Liu, and O. V. Yazyev, arXiv:1808.08178.
7. D. Gosálbez-Martínez, G. Autès, and O. V. Yazyev, arXiv:1811.08178.

Lieu

Bâtiment: Ecole de Physique

auditoire Stuckelberg

entrée libre