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Title
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Elusive s-f intrasite interactions and double exchange in solids: ferromagnetic versus nonmagnetic ground state
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Author
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Abstract
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| From the theory of many-electron states in atoms, we know that there exists a strong Coulomb repulsion, which results in the electronic term structure of atoms and is responsible for Hunds rules. By expanding the Coulomb on-site repulsion into a multipolar series, we derive this interaction and show that it is also present in solids as a correlation effect, which means that the interaction requires a multideterminant version of the Hartree-Fock method. Of particular interest is the case where this interaction couples states of localized ( f) and delocalized ( s) electrons. We show that the interaction is bilinear in the creation/annihilation operators for localized electrons and bilinear in the operators for conduction electrons. To study the coupling, we consider a simple model in the framework of an effective limited configuration interaction method with one localized f-electron and one itinerant s-electron per crystal site. The on-site multipole interaction between the f- and s-electrons is explicitly taken into account. It is shown that depending on the low-lying excitation spectrum imposed by the crystal electric field, the model can lead not only to ferromagnetism but also to a nonmagnetic state. The model is relevant for solids with localized and itinerant electron states. |
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Language
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English
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Source (journal)
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Journal of experimental and theoretical physics / American Institute of Physics. - Woodbury, N.Y., 1993, currens
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Publication
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Woodbury, N.Y.
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American Institute of Physics
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2009
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ISSN
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1063-7761
[print]
1090-6509
[online]
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Volume/pages
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109
:2
(2009)
, p. 286-292
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ISI
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000270506500014
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Full text (Publisher's DOI)
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