Topological phases and topological materials from elementary band representations
- Datum: 25.05.2018
- Uhrzeit: 10:15
- Vortragende(r): Dr. Maia Garcia Vergniory
- Donostia International Physics Center, Donostia, San Sebastian & IKERBASQUE, Bilbao, Spain
- Ort: Max-Planck-Institut für Mikrostrukturphysik, Weinberg 2, 06120 Halle (Saale)
- Raum: New Lecture Hall, Building B
The geometric phases of the single-particle wave functions turned out to be a very useful tool in band theory. Occupied states of a band insulator can be viewed from a topological perspective and reveal exotic transport properties in topological materials. During this talk, I will give an introduction to to- pology in condensed matter physic and a new way of de ning topology in materials. I will examine topological metals and insulators stabilized by any of the 230 crystal symmetry groups. By de ning the concept of elementary bandrepresentations of the double group augmented by time reversal, we can predict how many bandsare connected in momentum space based on the lattice positions (Wycko multiplicities) and character (s,p,d) of the elements/orbitals existent in the material. This allows for the prediction of symmetry-enforced semimetals whenever the valence number of electrons that occupies the orbitals is a fraction of the band connectivity. Our theory has discovered a new phase of topological materials: the high order topological insulators. This new phase has gapped bulk and surface states but displays hinge states.