Dresden 2014 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 79: Correlated Electrons - Poster Session
TT 79.46: Poster
Mittwoch, 2. April 2014, 15:00–19:00, P2
Fermi condensation near Van Hove singularities in the triangular lattice — •Daniel Hirschmeier1, Dmitry Yudin2, Hartmut Hafermann3, Olle Eriksson2, Alexander I. Lichtenstein1, and Mikhail I. Katsnelson4 — 1Institut für Theoretische Physik, Universität Hamburg, Jungiusstraße 9, D-20355 Hamburg, Germany — 2Department of Physics and Astronomy, Uppsala University, Box 516, SE-751 20 Uppsala, Sweden — 3Institut de Physique Théorique (IPhT), CEA, CNRS, 91191 Gif-sur-Yvette, France — 4Radboud University Nijmegen, Institute for Molecules and Materials, NL-6525, AJ Nijmegen, The Netherlands
The proximity of the Fermi surface to Van Hove singularities drastically enhances interaction effects and leads to essentially new physics. In this work we address the formation of flat bands ("Fermi condensation") within the Hubbard model on the triangular lattice and provide a detailed analysis from an analytical and numerical perspective. To describe the effect we consider both weak-coupling and strong-coupling approaches, namely the renormalization group and dual fermion methods. It is shown that the band flattening is driven by correlations and is well pronounced even at sufficiently high temperatures, of the order of 0.1-0.2 of the hopping parameter. The effect can therefore be probed in experiments with ultra cold fermions in optical lattices.