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Chern Numbers for Spin Models of Transition Metal Nanomagnets

C. M. Canali·A. Cehovin·A. H. MacDonald
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Abstract

We argue that ferromagnetic transition metal nanoparticles with fewer than approximately 100 atoms can be described by an effective Hamiltonian with a single giant spin degree of freedom. The total spin $S$ of the effective Hamiltonian is specified by a Berry curvature Chern number that characterizes the topologically non-trivial dependence of a nanoparticle's many-electron wavefunction on magnetization orientation. The Berry curvatures and associated Chern numbers have a complex dependence on spin-orbit coupling in the nanoparticle and influence the semiclassical Landau-Liftshitz equations that describe magnetization orientation dynamics.

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C. M. Canali, A. Cehovin, A. H. MacDonald. 2003-03-26. Chern Numbers for Spin Models of Transition Metal Nanomagnets. https://doi.org/10.1103/physrevlett.91.046805

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