@article{oai:niigata-u.repo.nii.ac.jp:00002123,
 author = {Mitsumoto, Keisuke and Ono, Yoshiaki},
 issue = {5},
 journal = {Journal of the Physical Society of Japan, Journal of the Physical Society of Japan},
 month = {May},
 note = {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 nf = 2 is more pronounced than that for quarter-filling with nf = 1.},
 pages = {054707-1--054707-7},
 title = {Cooperative Effect of Coulomb Interaction and Electron-Phonon Coupling on the Heavy Fermion State in the Two-Orbital Periodic Anderson Model},
 volume = {79},
 year = {2010}
}