Model of magnetic and charge superstructures in itinerant electron systems

Abstract

We present a simple microscopic model capable to describe charge and magnetic long range order in itinerant electron systems. This is the Falicov–Kimball model supplemented with an anisotropic, spin-dependent term. It contains localized and itinerant electrons coupled by the on-site interaction that represents Coulomb repulsion and the Hund's first rule. Ground-state properties of the system are studied rigorously on the infinite square lattice but the configurational space is restricted to the lowest-period phases only. In the current work we focus on stripe phases formed in the regime, where the density of localized electrons is fixed and equal to 1 2 . With a change of the density of itinerant electrons (band filling) from n d = 1 2 to n d = 1 it occurs a steadily rearrangement of axial stripes into diagonal stripes. The process follows a simple rule described in the text. As for the magnetic order both ferro- and various sorts of antiferromagnetic phases were detected.