Who: Tero Heikkilä (University of Jyväskylä, Finland)
Place: Auditorium of the Centro de Fisica de Materiales, Paseo Manuel de Lardizabal 5, Donostia-San Sebastián
Date: Tuesday, 27 October 2015, 11:00
University of Jyväskylä, Finland
Topological media: exotic particles and a possible route to room temperature superconductivity
One of the main focus points of condensed matter research in the past decade has been in the topological classification of media. This is a rather novel viewpoint in the characterization of the electronic properties of matter, and its successes include the prediction and observation of new classes of elements beyond the usual metals and insulators, for example topological insulators, nodal line semimetals and most recently Weyl semimetals. This approach also unites different branches of physics, as it gives a unified view on the emergent low-energy properties of matter. In my talk, I will show how the Berry phase analysis of the spectrum of a lattice periodic Hamiltonian leads to such a classification of elements. I will also demonstrate how the topological robustness shows up in the formation of protected (invariant to local deformations) surface and edge states in topological media. These surface states have intriguing properties, and especially in nodal line semimetals the interactions may lead to ordered states - such as superconductivity - with a very high critical temperature.