Magnetic Orderings and Phase Separations in the Zero-Bandwidth Limit of the Extended Hubbard Model with Intersite Magnetic Interactions
W. Kłobus, K. Kapcia and S. Robaszkiewicz
Electron States of Solids Division, Faculty of Physics, Adam Mickiewicz University, Umultowska 85, 61-614 Poznań, Poland
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A simple effective model for a description of magnetically ordered insulators is analysed. The tight binding Hamiltonian consists of the effective on-site interaction (U) and intersite magnetic exchange interactions (Jz, Jxy) between nearest neighbours. The phase diagrams of this model have been determined within the variational approach, which treats the on-site interaction term exactly and the intersite interactions within the mean-field approximation. We show that, depending on the values of interaction parameters and the electron concentration, the system can exhibit not only homogeneous phases: (anti-)ferromagnetic (Fα) and nonordered (NO), but also phase separated states (PSα: Fα-NO).
DOI: 10.12693/APhysPolA.118.353
PACS numbers: 71.10.Fd, 75.10.-b, 75.30.Gw, 64.75.Gh, 71.10.Hf