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arXiv · 0805.2167

Theory of the Magnetic Moment in Iron Pnictides

Jiansheng Wu·Philip Phillips·A. H. Castro-Neto
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Abstract

We show that the combined effects of spin-orbit, monoclinic distortion, and p-d hybridization in tetrahedrally coordinated Fe in LaOFeAs invalidates the naive Hund's rule filling of the Fe d-levels. The two highest occupied levels have one electron each but as a result of the p-d hybridization have very different on-site repulsions. As a result, electrons in the upper level are more itinerant while those in the lower level are more localized. It is the xy-projection of the spin in the lower level that orders antiferromagnetically as the z-components of the spins in the two levels is shown to be vanishingly small in the ground state. The resulting magnetic moment is highly anisotropic with an in-plane value of $0.25-0.35μ_B$ per Fe and a z-projection of $0.06μ_B$, both of which are in agreement with experiment. As a consequence, we arrive the minimal model that describes the electronic properties of LaOFeAs.

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Jiansheng Wu, Philip Phillips, A. H. Castro-Neto. 2008-09-17. Theory of the Magnetic Moment in Iron Pnictides. https://doi.org/10.1103/physrevlett.101.126401

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