Spin fluctuation-induced superconductivity controlled by orbital fluctuation

Takimoto, Tetsuya; Hotta, Takashi; Maehira, Takahiro; Ueda, Kazuo*

A microscopic Hamiltonian of the orbitally-degenerated Hubbard model reflecting correct symmetry of -orbitals is proposed to discuss superconductivity in -electron systems. In the degenerated region, cancellation among spin and orbital fluctuations basically destabilizes singlet superconductivity, while -wave superconductivity mediated by spin fluctuations emerges out of the suppression of orbital fluctuations due to the lift of orbital degeneracy. We argue that the present scenario can be applied to recently discovered Ce-based heavy-fermion superconductor.