Charge instabilities of the two-dimensional Hubbard model with attractive nearest neighbour interaction

18th International Conference on Recent Progress in Many-Body Theories

Frésard, Raymond^1 ; Steffen, Kevin^2 ; Kopp, Thilo^2

Laboratoire CRISMAT, UMR 6508 CNRS-ENSICAEN, Caen, France^1

Center for Electronic Correlations and Magnetism, EP VI, Institute of Physics, University of Augsburg, Augsburg

86135, Germany^2

关键词: Attractive interactions;    Extended Hubbard model;    Nearest-neighbour interactions;    Non-local interactions;    Particle-hole asymmetry;    Strong electronic correlations;    Two dimensional square lattice;    Van Hove singularities;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/702/1/012003/pdf
DOI  :  10.1088/1742-6596/702/1/012003

来源: IOP

【 摘 要 】

Attractive non-local interactions jointly with repulsive local interaction in a microscopic modelling of electronic Fermi liquids generate a competition between an enhancement of the static charge susceptibility-ultimately signalling charge instability and phase separation-and its correlation induced suppression. We analyse this scenario through the investigation of the extended Hubbard model on a two-dimensional square lattice, using the spin rotation invariant slave-boson representation of Kotliar and Ruckenstein. The quasiparticle density of states, the renormalised effective mass and the Landau parameter Fs0are presented, whereby the positivity of Fs0- 1 constitutes a criterion for stability. Van Hove singularities in the density of states support possible charge instabilities. A (negative) next-nearest neighbour hopping parameter t' shifts their positions and produces a tendency towards charge instability even for low filling whereas the t'-controlled particle-hole asymmetry of the correlation driven effective mass is small. A region of instability on account of the attractive interaction V is identified, either at half filling in the absence of strong electronic correlations or, in the case of large on-site interaction U, at densities far from half filling.