# Regensburg 2019 – wissenschaftliches Programm

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# TT: Fachverband Tiefe Temperaturen

## TT 37: Topological Semimetals - Theory (joint session TT/MA)

### TT 37.2: Vortrag

### Mittwoch, 3. April 2019, 09:45–10:00, H22

**Topological crossings in magnetic space groups** — •Darshan G. Joshi^{1}, Yang-hao Chan^{2}, and Andreas P. Schnyder^{1} — ^{1}Max-Planck-Institute for Solid State Research, Stuttgart, Germany — ^{2}Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei, Taiwan

Non-symmorphic symmetry is known to enforce topological crossings in crystals. Using the elementary band irreducible representations non-trivial crossings in the form of hour-glass or accordian spectrum have been discovered in certain space groups. Here we extend such an analysis to a wider domain of magnetic space groups (MSGs). We show that the magnetic co-representations (coreps), which are derived from the non-magnetic irreducible representations, can be used to detect non-symmorphic symmetry enforced topological crossings in MSGs. We demonstrate this with two examples, where we find magnetic Weyl points and hour-glass dispersions. DFT band-structure calculation of corresponding magnetic materials confirms our findings. Furthermore, we compute the surface states and discuss other experimental consequences of the hourglass dispersion in magnetic materials.