Exact studies of hybrid latticestatistical models of localized Ising spins and delocalized electrons

by Jozef Strecka (Kosice Slovakia)

Wednesday 26 Oct 2011, 11:15 → 12:15 Europe/Zurich

727 du BSP Cuotron (EPFL, Lausanne)

Two-dimensional lattice-statistical model, which describes the hybrid system of localized Ising spins and delocalized electrons, is exactly solved using the generalized decoration-iteration transformation when fixing the number of delocalized electrons per each couple of decorating sites. The ground state of the model with one electron delocalized over each couple of the decorating sites exhibits either a classical ferromagnetic or ferrimagnetic spontaneous long-range ordering, while the model with two delocalized electrons per each pair of the decorating sites displays a more striking four-sublattice quantum antiferromagnetic ordering with the obvious quantum reduction of the staggered magnetization. The ground state, critical behavior, order parameter and basic thermodynamic quantities will be calculated and analyzed in dependence on a relative strength of the hopping term and the Ising-type exchange interaction.