@article{oai:nagoya.repo.nii.ac.jp:00023020,
 author = {Tazai, Rina and Yamakawa, Youichi and Tsuchiizu, Masahisa and Kontani, Hiroshi},
 journal = {Physical Review B},
 month = {Sep},
 note = {In various multiorbital systems, the emergence of the orbital fluctuations and their role on the pairing mechanism attract increasing attention. To achieve deep understanding on these issues, we perform a functional renormalization group (fRG) study for the two-orbital Hubbard model. The vertex corrections for the electron-boson coupling (U-VC), which are dropped in the Migdal-Eliashberg gap equation, are obtained by solving the RG equation. We reveal that the dressed electron-boson coupling for the charge channel Uˆceff becomes much larger than the bare Coulomb interaction Uˆ0 due to the U-VC in the presence of moderate spin fluctuations. For this reason, the attractive pairing interaction due to the charge or orbital fluctuations is enlarged by the factor (Uˆceff/Uˆ0)2>>1. In contrast, the spin fluctuation pairing interaction is suppressed by the spin-channel U-VC, because of the relation Uˆseff<<Uˆ0. The present study demonstrates that the orbital or charge fluctuation pairing mechanism can be realized in various multiorbital systems thanks to the U-VC, such as in Fe-based superconductors.},
 pages = {115155--115155},
 title = {Functional renormalization group study of orbital fluctuation mediated superconductivity: Impact of the electron-boson coupling vertex corrections},
 volume = {94},
 year = {2016}
}