Dresden 2026 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 62: Correlated Electrons – Poster II
TT 62.12: Poster
Wednesday, March 11, 2026, 15:00–17:00, P4
Emergent relativity and topology of interacting quadratic fermions — •Lukas Berger and Thomas C. Lang — Institute for Theoretical Physics, University of Innsbruck, Austria
We investigate the lattice realization of perfect quadratic band touching of fermions augmented by local Coulomb interactions via quantum Monte Carlo simulations. We show that due to the C4 rotational symmetry of the lattice, interactions trigger an instability towards quantum anomalous Hall order. In contrast, once the rotational symmetry of the lattice is reduced to C2, infinitesimally small interactions dynamically induce a topological transition from quadratic band touching to multiple Dirac cones before undergoing a Gross-Neveu transition where lattice symmetry is spontaneously broken via charge order. We directly monitor the separation of the Berry flux and the simultaneous emergence of Dirac-like excitation spectra.
Keywords: quadratic band touching; quantum monte carlo; anomalous hall effect; lifshitz transition