Research group “Topological materials”

© Heinrich Pniok

Beginning with the discovery of the first three-dimensional weak topological insulator by Dr. Bertold Rasche (B. Rasche, A. Isaeva, M. Ruck, S. Borisenko, V. Zabolotnyy, B. Büchner, K. Koepernik, C. Ortix, M. Richter, J. van den Brink, Nat. Mater. 2013, 12, 422–425.) a research group under supervision of Dr. Anna Isaeva was developed, focusing on the explorative research on new topological non-trivial materials. Next to Dr. Isaeva the group currently consists of the four PhD students Mai Lê Anh, Paul Gebauer, Maria Herz and Eduardo Carrillo. The group is targeting systems containing heavy atoms, which underlie a strong spin-orbit coupling essential for the sought-for properties. The spectrum ranges from halides and chalcogenides of bismuth to mixed ternary Compounds (Bi_nTeHal; n = 2,3; Hal = Br, I), as well as the combination of the aforementioned with transition and rare earth elements. Following the exploration of new materials, the research group develops methods for single crystal growth to obtain crystals suitable for physical characterization. A broad network of national and international cooperations enables characterizations from quantum mechanical calculations to highly specialized physical characterization of new materials. Thus, the research group is involved in both the SPP 1666 and the international ERA-Chemistry project of the Deutsche Forschungsgemeinschaft (DFG).

A selection of published articles:

• Bi₁₄Rh₃I₉ - First experimentally confirmed weak 3D TI

[1] B. Rasche, A. Isaeva, M. Ruck et al., Nat. Mater. 2013, 12, 422–425.

[2] B. Rasche, A. Isaeva, A. Gerisch, M. Kaiser, W. Van den Broek, C. T. Koch, U. Kaiser, M. Ruck, Chem. Mater. 2013, 25, 2359–2364.

[3] A. Isaeva, B. Rasche, M. Ruck, Phys. Status Solidi RRL 2013, 7, 39–49.

[4] B. Rasche, A. Isaeva, M. Ruck, K. Koepernik, M. Richter, J. van den Brink, Sci. Rep. 2016, 6, 20645.

• ß-Bi₄I₄ - A strong 3D TI with pronounced anisotropy and tentative superconductivity under pressure

[5] G. Autès, A. Isaeva, L. Moreschini, J. C. Johannsen et al., Nat. Mater. 2016, 15, 154.

[6] A. Pisoni, R. Gaál, A. Zeugner, V. Falkowski, A. Isaeva, H. Huppertz, G. Autès, O. V. Yazyev, L. Forró, Phys. Rev. B 2017, 95, 235149.

• Bi_nTeHal (n = 2,3; Hal = Br, I) - A family of modular structures with topological properties changing upon bismuth content

[7] I. P. Rusinov, T. V. Menshchikova, A. Isaeva et al., Sci. Rep. 2016, 6, 20734.

[8] A. Zeugner, M. Kaiser, P. Schmidt, T. V. Menshchikova, I. P. Rusinov, M. Ruck, A. Isaeva et al., Chem. Mater. 2017, 29, 1321–1337.

[9] N. Avraham, A. Norris, Y. Sun, Y. Qi, L. Pan, A. Isaeva, A. Zeugner, C. Felser, B. Yan, H. Beidenkopf, arXiv:1708.09062 2017.

[10] A. Zeugner, J. Teichert, M. Kaiser, T. V. Menshchikova, I. P. Rusinov, T. Doert, M. Ruck, A. Isaeva et al., Chem. Mater. 2018, 30, 5272–5284.

• MnBi₂Te₄ - Putative first antiferromagnetic topological insulator

[11] M. M. Otrokov, I. I. Klimovskikh, H. Bentmann, A. Zeugner, Z. S. Aliev, S. Gaß, A. U. B. Wolter, A. V. Koroleva, D. Estyunin, A. Isaeva, et al., arXiv:1809.07389 2018.