Phonon softening and double-well potential formation due to electron-phonon interaction in heavy-fermion systems

Abstract

We investigate the periodic Anderson-Holstein model by using the dynamical mean-field theory combined with the exact diagonalization method. For the strong electron-phonon coupling $g\simg g_c$, the system shows an anomalous heavy-fermion behaviour which is accompanied by a large lattice fluctuation and an extreme phonon softening. We also calculate an effective potential for the ions and find that a simple harmonic potential for $g\siml g_c$ changes into a double-well potential for $g\simg g_c$. The effective pairing interaction between the conduction electrons shows a maximum at $g\approx g_c$ where the superconducting transition temperature is expected to be maximum.

arXiv comment5 pages, 4 figures, accepted for publication in Physica C

References in corpus (5)

• Quadrupolar effect and rattling motion in heavy fermion superconductor PrOs_4Sb_{12}
• Gap formation and soft phonon mode in the Holstein model
• Ferroquadrupole ordering and Gamma_5 rattling motion in clathrate compound Ce_3Pd_20Ge_6
• First- and Second Order Phase Transitions in the Holstein-Hubbard Model
• Two-Channel Kondo Model as a Fixed Point of Local Electron-Phonon Coupling System

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• Low-lying excitations at the rare-earth site due to rattling motion in the filled skutterudite LaOs_4Sb_{12} revealed by ^{139}La NMR and ^{121/123}Sb NQR
• Enhanced Kondo Effect in an Electron System Dynamically Coupled with Local Optical Phonon
• Single polaron properties for double-well electron-phonon coupling
• Theory of Ultrasonic Dispersion in Local Phonon Systems Coupled with Conduction Electrons
• Inverse Isotope Effect on Kondo Temperature in Electron-Rattling System
• Phonons and the coherence scale of models of heavy fermions
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• Strong-Coupling Theory of Rattling-Induced Superconductivity
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• Cooperative Effect of Coulomb Interaction and Electron-Phonon Coupling on the Heavy Fermion State in the Two-Orbital Periodic Anderson Model
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• Electron Mass Enhancement due to Anharmonic Local Phonons
• Periodic Anderson model with electron-phonon correlated conduction band
• Heavy-Electron Formation and Bipolaronic Transition in the Anharmonic Holstein Model
• Electric Dipolar Susceptibility of the Anderson-Holstein Model
• Metal-insulator transition and superconductivity in the two-orbital Hubbard-Holstein model for iron-based superconductors