Berlin 2015 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 112: Correlated Electrons: (General) Theory 3
TT 112.7: Talk
Friday, March 20, 2015, 11:15–11:30, H 3010
First order character and observable signatures of topological quantum phase transitions — •Adriano Amaricci1, Jan Budich2,3, Bjoern Trauzettel4, Massimo Capone1, and Giorgio Sangiovanni4 — 1Democritos National Simulation Center, Consiglio Nazionale delle Ricerche, Istituto Officina dei Materiali (IOM) and Scuola Internazionale Superiore di Studi Avanzati (SISSA), Via Bonomea 265, 34136 Trieste, Italy — 2Institute for Theoretical Physics, University of Innsbruck, 6020 Innsbruck, Austria — 3Institute for Quantum Optics and Quantum Information, Austrian Academy of Sciences, 6020 Innsbruck, Austria — 4Institut fur Theoretische Physik und Astrophysik, Universitat Wuerzburg, Am Hubland, D-97074 Wuerzburg, German
Topological quantum phase transitions are characterised by changes in global topological invariants beyond the paradigm of spontaneous symmetry breaking. For non-interacting electrons, such transitions are continuous and always accompanied by a gap-closing in the energy spectrum. Here, we demonstrate that sufficiently strong electron-electron interaction can fundamentally change the situation: we discover a topological quantum phase transition of first order character in the genuine thermodynamic sense, that occurs without gap closing. Our theoretical study reveals the existence of a quantum critical endpoint associated with an orbital instability on the transition line between a 2D topological insulator and a trivial band insulator. Remarkably, this phenomenon entails unambiguous signatures associated to the orbital occupations that can be detected experimentally.