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CPA Treatment of the Hubbard Model with Intra‐Atomic Exchange Interaction
Author(s) -
Mizia J.
Publication year - 1976
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.2220740206
Subject(s) - ferromagnetism , condensed matter physics , coulomb , hubbard model , exchange interaction , degenerate energy levels , hamiltonian (control theory) , magnetization , electron , physics , atom (system on chip) , electronic correlation , uncorrelated , quantum mechanics , magnetic field , superconductivity , mathematics , mathematical optimization , statistics , computer science , embedded system
The Hamiltonian for a completely degenerate d‐band including intra‐atomic Coulomb and exchange interactions is derived and studied using the alloy analogy method. Green's function, the magnetic susceptibility and a criterion for the appearance of ferromagnetism are obtained by this method. The dependence of the magnetization on the exchange constant and on the number of electrons per atom is calculated for strong Coulomb correlation and for the uncorrelated case. It is shown that Coulomb correlation of any strength leads to a decrease of the exchange interaction constant needed to produce ferromagnetism and additionally to a change in the shapes of the magnetic dependences for (and only for) weakly ferromagnetic metals.