EXACT GROUND-STATE IN AN ORBITALLY DEGENERATE HUBBARD-MODEL

We present an exact solution on the ground stale of a one-dimensional orbitally degenerate Hubbard model in the ease of strong coupling, and the phase diagram in terms of electron filling and relevant parameter s. The ground state is nondegenerate apart for spin SU(2) symmetry and a fully saturated and metallic ferromagnet except the case of the qua rter filling, at which a ferromagnetic Mott insulator transition occur s. The phase diagram shows coexistence of ferromagnetism and spin-trip let pairing superconductivity when the Hund coupling is sufficiently l arger. A mechanism for spin-triplet pairing superconductivity and its possible relevance to the quasi-one-dimensional organic superconductor are proposed.