Effect of on-site Coulomb repulsion on phase transitions in exactly solved spin-electron model

A hybrid lattice-statistical model on doubly decorated planar lattices, which have localized Ising spins at their nodal lattice sites and two itinerant electrons at each pair of decorating sites, is exactly solved by the use of a generalized decoration-iteration transformation. Our main attention is focused on an in uence of the on-site Coulomb repulsion on ground-state properties and critical behavior of the investigated system.Comment: 2 pages, 3 figures, presented at 14th Czech and Slovak Conference on Magnetism 6.-9. July 2010, Kosice, Slovaki

Spin-1/2 XXZ diamond chain within the Jordan-Wigner fermionization approach

The spin-1/2 XXZ diamond chain is considered within the Jordan-Wigner fermionization. The fermionized Hamiltonian contains the interacting terms which are treated within the Hartree-Fock approximation. We obtain the ground-state magnetization curve of the model for some particular cases and compare the results with the exact diagonalization data for finite chains of 30 spins and known exact results. We also analyze the validity of the suggested approximation.Comment: 2 pages, 1 figure, presented at 14th Czech and Slovak Conference on Magnetism 6.-9. July 2010, Kosice, Slovaki