Abstract
We study tight-binding models of itinerant electrons in two different bands, with effective on-site interactions expressing Coulomb repulsion and Hund’s rule. We prove that, for sufficiently large on-site exchange anisotropy, all ground states show metallic ferromagnetism: They exhibit a macroscopic magnetization, a macroscopic fraction of the electrons is spatially delocalized, and there is no energy gap for kinetic excitations.
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Fröhlich, J., Ueltschi, D. Hund’s Rule and Metallic Ferromagnetism. J Stat Phys 118, 973–978 (2005). https://doi.org/10.1007/s10955-004-2174-y
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DOI: https://doi.org/10.1007/s10955-004-2174-y