Superconductivity in a multiorbital model for the Γ3 crystalline electric field state

Superconductivity in a three-orbital model for the Γ3 crystalline electric field (CEF) ground state is investigated by applying the random phase approximation. In this model, we assume an antiferromagnetic interaction between the Γ7 and Γ8 orbitals to stabilize the Γ3 CEF state among f2 states. This interaction may induce spin-singlet pairing between electrons in these orbitals. If we consider the onsite pairing state composed of the Γ7 and Γ8 orbitals, it has the Eg symmetry. Indeed, we find that the Eg spin-singlet superconducting state is realized in a wide parameter region. Possible coexistence of the superconductivity and quadrupole order is also discussed.