Ordered States in Periodic Anderson Hamiltonian with Orbital Degeneracy and with Large Coulomb Correlation

Ordered states of a periodic Anderson Hamiltonian with large Coulomb correlation and with orbital degeneracy of localized levels are theoretically investigated. When the number of f electrons is nearly one per site, and when the exchange interaction is antiferromagnetic as a whole, it is predicted that an antiferromagnetic type ordering occurs in the orbital order of localized levels at a certain low temperature accompanied by the lattice distortion due to the Jahn-Teller effect, and that a ferromagnetic or an antiferromagnetic ordering of spin, if it occurs, occurs at a lower temperature. One of the most characteristic features of this orbital ordered state is a strong coupling between orbital antiferromagnetic moments and spin ferromagnetic ones. It is tried to explain the experimental data of CeB 6 with a model that a quartet is the ground multiplet of localized levels.