Showing papers by "Mikhail A. Zagrebin published in 2011"
TL;DR: In this paper, a microscopic Hamiltonian for a ferromagnet with two degenerate bands was investigated and a macroscopic free energy was obtained from the microscopic Hubbard Hamiltonian, taking into account the Jahn-Teller effect.
Abstract: In this work a microscopic Hamiltonian is investigated using the Hubbard model for a ferromagnet with two degenerate bands, taking into account the Jahn-Teller effect. A macroscopic free energy is obtained from the microscopic Hubbard Hamiltonian. All free energy coefficients depend on microscopic parameters: temperature T and composition x . As a result of analytical minimization of free energy, phase diagrams are numerically constructed. It is shown that at certain values of parameters on the phase diagrams there are thermodynamic paths which correspond to experimentally observed sequences of phase transitions. Using density of states spectra for different compositions x the T - x phase diagram is numerically constructed. This phase diagram can theoretically explain experimentally observed behavior of the temperatures of phase transitions.