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arXiv · 0706.3353

Microscopic origin of isotropic non-Heisenberg behavior in highly correlated systems

Roland Bastardis·Nathalie Guihery·Coen de Graaf
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Abstract

We have reanalyzed the microscopic origin of the isotropic deviations that are observed from the energy spacings predicted by the HDVV Hamiltonian. Usually, a biquadratic spin operator is added to the HDVV Hamiltonian to account for such deviations. It is shown here that this operator cannot describe the effect of the excited atomic non-Hund states which brought the most important contribution to the deviations. For systems containing more than two magnetic centers, non-Hund states cause additional interactions that are of the same order of magnitude as the biquadratic exchange and should have significant effects on the macroscopic properties of extended systems.

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Roland Bastardis, Nathalie Guihery, Coen de Graaf. 2007-06-22. Microscopic origin of isotropic non-Heisenberg behavior in highly correlated systems. https://doi.org/10.1103/physrevb.76.132412

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