Charge and magnetic order in mixed valence systems

We analyze charge and magnetically ordered phases in systems described by a generalized FalicovKimball model, with a spin-dependent interaction term representing the Hund's rule. We study ground state properties of the model rigorously on the infinite 2D square lattice, but within the restricted configurational space, composed of all periodic phases (and their mixtures), for which the number of sites per unit cell is less or equal to 4. In the current work we focus on the mixed valence regime, where the total density of electrons is fixed and equal to 1. For a range of intermediate values of the interaction parameters we detected stable charge and magnetic superstructures of the form of stripes. They display various magnetic arrangements of the localized elctrons, including ferri- and antiferromagnetic, despite of the assumption of the ferromagnetic on-site coupling.