Phase diagram of the one dimensional Hubbard-Holstein Model at 1/2 and 1/4 filling

Abstract

The Hubbard-Holstein model is one of the simplest to incorporate both electron-electron and electron-phonon interactions. In one dimension at half filling the Holstein electron-phonon coupling promotes onsite pairs of electrons and a Peierls charge density wave while the Hubbard onsite Coulomb repulsion U promotes antiferromagnetic correlations and a Mott insulating state. Recent numerical studies have found a possible third intermediate phase between Peierls and Mott states. From direct calculations of charge and spin susceptibilities, we show that (i) As the electron-phonon coupling is increased, first a spin gap opens, followed by the Peierls transition. Between these two transitions the metallic intermediate phase has a spin gap, no charge gap, and properties similar to the negative-U Hubbard model. (ii) The transitions between Mott/intermediate and intermediate/Peierls states are of the Kosterlitz-Thouless form. (iii) For larger U the two transitions merge at a tritical point into a single first order Mott/Peierls transition. In addition we show that an intermediate phase also occurs in the quarter-filled model.

10 pages, 10 eps figures

References in corpus (3)

• Quantum lattice dynamical effects on the single-particle excitations in 1D Mott and Peierls insulators
• Retardation effects in the Holstein-Hubbard chain at half-filling
• Dominant particle-hole contributions to the phonon dynamics in the spinless one-dimensional Holstein model

Cited by in corpus (4)

• Metallicity in the half-filled Holstein-Hubbard model
• Temperature-driven transition from the Wigner Crystal to the Bond-Charge-Density Wave in the Quasi-One-Dimensional Quarter-Filled band
• Charge ordering and magnetism in quarter-filled Hubbard-Holstein model
• Gutzwiller scheme for electrons and phonons: the half-filled Hubbard-Holstein model