Energy spectrum analysis and finite temperature properties of the Falicov-Kimball model with Hund coupling at half filling

Abstract

The Falicov-Kimball model supplemented with the Ising-type Hund coupling describes charge and magnetic order induced by on-site, charge-, and spin-dependent interactions between itinerant electrons and localized ions. Motivated by a discovery of the rich structure of ground-state phase diagrams containing various charge and magnetic superstructures, we analyze the energy spectrum and determine numerically finite temperature properties of the model on the square 4 ϫ 4 cluster at half filling. For the density of magnetic ions equal to 1 and 1/2 and not too small coupling constants we show that many-electron collective excitations derived from changes in positions of the ions or inversions their spins have much lower energy than single-electron excitations. From an analysis of the excitation spectrum structure we derive effective interactions between the ions. When the coupling constants are large enough the interactions reduce to two-body forces between ions occupying the nearest-neighboring sites. Finite-temperature characteristics and temperatures of transformation from charge or magnetically ordered to disordered phases are determined in the wide range of the interaction couplings.

Formation of charge and spin ordering in strongly correlated electron systems

“…It should be noted that similar calculations of finite temperature properties of the model have been recently performed by Wrzodak and Lemanski[129] on the square 4 × 4 cluster at half-filling.…”

Electronic transport through correlated electron systems with nonhomogeneous charge orderings

“…This opens a vast variety of problems that can be addressed by the used method and various extensions of the FKM. Besides investigating other regimes of the spinless FKM, e.g., the vicinity of the PHS case where various nonhomogeneouse axial orderings compete with full CDW phase [71], insight into the spin-resolved current can be gained from the investigation of the transport through the spinfull version of the FKM, where the homogeneous charge orderings are accompanied by different spin orderings [76,129,130]. Such studies are expected to be particularly interesting in the context of spintronics.…”