# Berlin 2018 – wissenschaftliches Programm

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# HL: Fachverband Halbleiterphysik

## HL 7: Topological insulators I (joint session HL/TT)

### HL 7.1: Vortrag

### Montag, 12. März 2018, 09:30–09:45, A 151

**Model for ferromagnetic Weyl and nodal line semimetals: topological invariants, surface states, anomalous and spin Hall effect** — Tomáš Rauch^{1,2}, Huong Nguyen-Minh^{1}, •Jürgen Henk^{1}, and Ingrid Mertig^{1,3} — ^{1}Institute of Physics, Martin Luther University Halle-Wittenberg, Halle, Germany — ^{2}Berc Materials Physics Center, Donostia–San Sebastián, Spain — ^{3}Max Planck Institute for Microstructure Physics, Halle, Germany

By adding a Zeeman term to the extended Dirac equation [1] we show that this equation describes not only topological insulators but also models the electronic properties of ferromagnetic Weyl and nodal line semimetals [2], both of which arise for specific parameter sets. We confirm the topological nontriviality of the nodal objects by calculating the topological invariants as well as by demonstrating the existence of characteristic topological surface states of the associated semi-infinite systems. Moreover, Weyl points and nodal lines produce notable features in the anomalous and in the spin Hall conductivity.

[1] S.-Q. Shen, W.-Y. Shan, and H.-Z. Lu, Spin **1**, 33 (2011).

[2] T. Rauch, H. Nguyen-Minh, J. Henk, and I. Mertig, Phys. Rev. B, submitted.