Construction of a microscopic model for -electron systems on the basis of - coupling scheme

Hotta, Takashi; Ueda, Kazuo

We construct a microscopic model for -electron systems, composed of -electron hopping, Coulomb interaction, and crystalline electric field terms. based on the - coupling scheme. The Hamiltonian obtained is regarded as an orbital degenerate Hubbard model, since it includes two pseudo-spin and three pseudo-orbital degrees of freedom. For practical purposes, it is further simplified into a couple of two-orbital models by discarding one of the three orbitals. One of those simplified models is here analyzed using the exact diagonalization method to clarify ground-state properties by evaluating several kinds of correlation functions. We attempt to discuss a possible relation of the present results with experimental observations for recently discovered heavy fermion superconductors CeMIn (M=Ir, Co, and Rh), and a comprehensive scenario to understand superconducting and antiferromagnetic tendencies in the so-called ``115'' materials such as CeMIn, UMGa, and PuCoGa from the microscopic viewpoint.