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Article Dans Une Revue Physical Review B: Condensed Matter and Materials Physics (1998-2015) Année : 2019

One-dimensional Hubbard-Holstein model with finite range electron-phonon coupling

Résumé

The Hubbard-Holstein model describes fermions on a discrete lattice, with on-site repulsion between fermions and a coupling to phonons that are localized on sites. Generally, at half-filling, increasing the coupling $g$ to the phonons drives the system towards a Peierls charge density wave state whereas increasing the electron-electron interaction $U$ drives the fermions into a Mott antiferromagnet. At low $g$ and $U$, or when doped, the system is metallic. In one-dimension, using quantum Monte Carlo simulations, we study the case where fermions have a long range coupling to phonons, with characteristic range $\xi$, interpolating between the Holstein and Fr\"ohlich limits. Without electron-electron interaction, the fermions adopt a Peierls state when the coupling to the phonons is strong enough. This state is destabilized by a small coupling range $\xi$, and leads to a collapse of the fermions, and, consequently, phase separation. Increasing interaction $U$ will drive any of these three phases (metallic, Peierls, phase separation) into a Mott insulator phase. The phase separation region is once again present in the $U \ne 0$ case, even for small values of the coupling range.

Dates et versions

hal-02009899 , version 1 (06-02-2019)

Identifiants

Citer

Frédéric Hébert, Bo Xiao, V. G. Rousseau, R. T. Scalettar, G. G. Batrouni. One-dimensional Hubbard-Holstein model with finite range electron-phonon coupling. Physical Review B: Condensed Matter and Materials Physics (1998-2015), 2019, 99 (7), ⟨10.1103/PhysRevB.99.075108⟩. ⟨hal-02009899⟩
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