Magnetic Properties of Itinerant Electrons in Triangular Lattices

Abstract

The investigation of the magnetic properties of itinerant electron systems has been object of enormousinterest of statistical physics since the beginning of quantum theory. During all this time it has importantprogress in the understanding of diverse systems, but little effort was used in the elucidation of thespecific properties of systems in lattices with triangular structures that present frustration inantiferromagnetic correlations. In order to contribute to a better understanding of these systems we usethe method of the equation of motion of the Green function on the Hubbard model to calculate the densityof states and the magnetic thermodynamic properties of a paramagnetic system with half-filled-band inthe cases of triangular and face centered cubic (fcc) lattices. We determine the internal energy and themagnetic susceptibility in function of the temperature (T) and the on-site Coulomb repulsion (U). Theresults show the strong dependence of the examined quantities with T and U. Particularly, we explicit thedependence of the critical temperature (Tc) with U in the ferromagnetic-paramagnetic transition, and thecritical value of the interaction (Uc) from which the system can present ferromagnetism.