Superconductivity in a multiorbital model for the crystalline electric field state

Kubo, Katsunori 

A cubic system with the cubic crystalline electric field (CEF) state is an ideal system to investigate multipole physics, since it does not have dipole but has higher-order multipoles such as quadrupole and octupole. In addition, superconductivity has been observed in PrTX (T = Ir, Rh, X = Zn; T = Ti, V, X = Al) systems with the CEF ground state. To approach these phenomena theoretically, we consider a model composed of f electrons with the total angular momentum . From this model, we have derived multipole interactions for the systems. In the present study, we investigate superconductivity in the same model. We apply random phase approximation for superconductivity in a multiorbital system to the present model. Then, we have obtained a d-wave spin-singlet state. We will discuss the relevance of the present theory to the PrTX superconductors.