2014/11/30 by A. Amaricci, Jan Carl Budich, J. C. Budich +6 · 118 citations
Mathematics · Physics and Astronomy · #Character (mathematics) #Cold Atom Physics and Bose-Einstein Condensates #Combinatorics #Geometry #Mathematics #Observable #Order (exchange) #Phase (matter) #Phase transition #Physics #Quantum #Quantum many-body systems #Quantum mechanics #Quantum phase transition #Statistical physics #Theoretical physics #Topological Materials and Phenomena #Topological order #Topology (electrical circuits) #cond-mat.str-el
paper · pdf · doi:10.1103/physrevlett.114.185701
published in Physical Review Letters 114(18), 185701 (American Physical Society) · 5 pages, 3 figures. Updated Fig. 1 and updated discussion of the first-order transition
openalex publication_date 2015/05/08 · arxiv created 2015/05/09 · arxiv updated 2015/05/12 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
Topological quantum phase transitions are characterized by changes in global topological invariants. These invariants classify many-body systems beyond the conventional paradigm of local order parameters describing spontaneous symmetry breaking. For noninteracting electrons, it is well understood that such transitions are continuous and always accompanied by a gap closing in the energy spectrum, given that the symmetries protecting the topological phase are maintained. Here, we demonstrate that a 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 a 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 related to the orbital occupations that can be detected experimentally.