2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/23786We study tight-binding models of itinerant electrons in two different bands, with effective on-site interactions expressing Coulomb repulsion and Hund's rule. We prove that, for sufficiently large on-site exchange anisotropy, all ground states show metallic ferromagnetism: They exhibit a macroscopic magnetization, a macroscopic fraction of the electrons is spatially delocalized, and there is no energy gap for kinetic excitations.17 pagesStrongly Correlated ElectronsStatistical MechanicsMathematical Physicstext