# Dresden 2017 – wissenschaftliches Programm

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# DS: Fachverband Dünne Schichten

## DS 33: Transport: Topological Semimetals 2 (jointly with MA/TT)

### DS 33.6: Vortrag

### Mittwoch, 22. März 2017, 16:30–16:45, HSZ 204

**Magnetic Properties of Dirac Fermions in a Family of Anti-perovskites** — •Moritz Mandes Hirschmann and Andreas Philipp Schnyder — Max Planck Institute for Solid State Research, Stuttgart, Germany

We study the magnetic properties of the anti-perovskite materials A_{3}EO, where A denotes an alkaline earth metal, while E stands for Pb or Sn. The low-energy electronic properties of this family of anti-perovskites is described by three-dimensional Dirac fermions, which are gapped out by spin-orbit coupling [1-3]. We discuss the magnetic response of this Dirac electron system, considering both orbital and spin Zeeman effects. Interestingly, a strong Zeeman field splits the gapped Dirac cones into ungapped Weyl points, which are protected by a quantized Chern number. The compound Eu_{3}PbO breaks in its ferromagnetic phase intrinsically the time-reversal symmetry by exhibiting a magnetization that corresponds to a large Zeeman splitting at the Europium atoms. Again we observe Weyl points in the band structure. Using a tight-binding description we calculate these Chern numbers and demonstrate that the Weyl points are connected by Fermi arcs in the surface Brillouin zone.
Furthermore, we determine the Landau level structure of the gapped Dirac electrons.

[1] T. H. Hsieh, J. Liu, and L. Fu. *Phys. Rev. B*, 90:081112, Aug 2014

[2] J. Nuss, C. Mühle, K. Hayama, V. Abdolazimi, and H. Takagi. *Acta Crystallographica Section B*, 71(3):300-312, Jun 2015.

[3] D. Samal, H. Nakamura, and H. Takagi. *APL Mater.*, 4(7), 2016.