Metal-insulator transition, gap opening due to the combined orbital-spin ordering, and spin-triplet superconductivity

We consider a metal-insulator transition for the quarter-filled doubly dege nerate band of correlated electrons, as well as the onset of the itinerant orbitally ordered phase combined with the saturated ferromagnetism near tha t limit. The insulating state is instable with respect to either spin-tripl et superconductivity or that of ferromagnetic superconductor for strong-eno ugh Hund's-rule coupling. The auxiliary (slave) boson approach we use repro duces correctly the kinetic-exchange limit for strong correlations.