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Density-of-states picture and stability of ferromagnetism in the highly-correlated Hubbard model

V. Yu. Irkhin·A. V. Zarubin
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Abstract

The problem of stability of saturated and non-saturated ferromagnetism in the Hubbard model is considered in terms of the one-particle Green's functions. Approximations by Edwards and Hertz and some versions of the self-consistent approximations based on the 1/z-expansion are considered. The account of longitudinal fluctuations turns out to be essential for description of the non-saturated state. The corresponding pictures of density of states are obtained. "Kondo" density-of-states singularities owing to spin-flip processes are analyzed. The critical electron concentrations for instabilities of saturated ferromagnetism and paramagnetic state are calculated for various lattices. Drawbacks of various approximations are discussed. A comparison with the results of previous works is performed.

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V. Yu. Irkhin, A. V. Zarubin. 2004-01-23. Density-of-states picture and stability of ferromagnetism in the highly-correlated Hubbard model. https://doi.org/10.1103/physrevb.70.035116

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