Effective electron-phonon coupling and polaronic transition in the presence of strong correlation

Abstract

We study the Hubbard-Holstein model using slave-boson mean-field and a variation al Lang-Firsov transformation. We identify weak and strong e-ph coupling solutions, whose stability depends both on the bare e-ph coupling and on the correlation strength. At mean field level the evolution from weak to strong electron-phonon coupling occurs via a first-order polaronic transition if the adiabatic parameter is below a critical value. In the strongly correlated regime and in the adiabatic limit, the region in which the weak-coupling solution is stable is sizeably enlarged with respect to the weakly correlated system and the Mott metal-insulator transition is found to be robust with respect to e-ph interaction.

arXiv comment6 pages, 2 figures

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• Relevance of phonon dynamics in strongly correlated systems coupled to phonons: A Dynamical Mean Field Theory analysis
• Gutzwiller scheme for electrons and phonons: the half-filled Hubbard-Holstein model
• Polaronic effects in one- and two-band quantum systems
• Extended Gutzwiller wavefunction for the Hubbard-Holstein model
• Mixed-state phase transitions in spin-Holstein models
• Competing Correlated Insulators in multi-orbital systems coupled to phonons
• Intertwined fluctuations and isotope effects in the Hubbard-Holstein model on the square lattice from functional renormalization