Cooperative Effect of Coulomb Interaction and Electron-Phonon Coupling on the Heavy Fermion State in the Two-Orbital Periodic Anderson Model

Abstract

We investigate the two-orbital periodic Anderson model, where the local orbital fluctuations of f-electrons couple with a two-fold degenerate Jahn-Teller phonon, by using the dynamical mean-field theory. It is found that the heavy fermion state caused by the Coulomb interaction between f-electrons U is largely enhanced due to the electron-phonon coupling g, in contrast to the case with the single-orbital periodic Anderson model where the effects of U and g compete to each other. In the heavy fermion state for large $U$ and g, both the orbital and lattice fluctuations are enhanced, while the charge (valence) and spin fluctuations are suppressed. In the strong coupling regime, a sharp soft phonon mode with a large spectral weight is observed for small U, while a broad soft phonon mode with a small spectral weight is observed for large U. The cooperative effect of U and g for half-filling with two f-electrons per atom $n_f=2$ is more pronounced than that for quarter-filling with $n_f=1$.

8 pages, 11 figures, accepted for publication in JPSJ

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Cited by in corpus (6)

• Kondo Effect of a Magnetic Ion Vibrating in a Harmonic Potential
• Heavy-Electron Formation and Bipolaronic Transition in the Anharmonic Holstein Model
• Electric Dipolar Susceptibility of the Anderson-Holstein Model
• Kondo Effect of a Jahn-Teller Ion Vibrating in a Cubic Anharmonic Potential
• Metal-insulator transition and superconductivity in the two-orbital Hubbard-Holstein model for iron-based superconductors
• Chaos in Jahn-Teller Rattling