Monte Carlo Study of Phase Separation in Magnetic Insulators
S. Murawski, K.J. Kapcia, G. Pawłowski and S. Robaszkiewicz
Electron States of Solids Division, Faculty of Physics, Adam Mickiewicz University in Poznań, Umultowska 85, 61-614 Poznań, Poland
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In this work we focus on the study of phase separation in the zero-bandwidth extended Hubbard with nearest-neighbors intersite Ising-like magnetic interactions J and on-site Coulomb interactions U. The system has been analyzed by means of the Monte Carlo simulations (in the grand canonical ensemble) on two-dimensional square lattice (with N = L × L = 400 sites) and the results for U/(4J) = 2 as a function of chemical potential and electron concentration have been obtained. Depending on the values of interaction parameters the system exhibits homogeneous (anti-)ferromagnetic or non-ordered phase as well as phase separation state. Transitions between homogeneous phases (i.e. antiferromagnetic-non-ordered transitions) can be of first or second order and the tricritical point is also present on the phase diagrams. The electron compressibility K is an indicator of the phase separation and that quantity is of particular interest of this paper.

DOI: 10.12693/APhysPolA.127.281
PACS numbers: 71.10.Fd, 75.10.-b, 75.30.Fv, 64.75.Gh, 71.10.Hf