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Magnon Dispersion and Anisotropies in SrCu$_2$(BO$_3$)$_2$

Y. F. Cheng·O. Cepas·P. W. Leung·T. Ziman
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Abstract

We study the dispersion of the magnons (triplet states) in SrCu$_2$(BO$_3$)$_2$ including all symmetry-allowed Dzyaloshinskii-Moriya interactions. We can reduce the complexity of the general Hamiltonian to a new simpler form by appropriate rotations of the spin operators. The resulting Hamiltonian is studied by both perturbation theory and exact numerical diagonalization on a 32-site cluster. We argue that the dispersion is dominated by Dzyaloshinskii-Moriya interactions. We point out which combinations of these anisotropies affect the dispersion to linear-order, and extract their magnitudes.

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Y. F. Cheng, O. Cepas, P. W. Leung, T. Ziman. 2007-04-20. Magnon Dispersion and Anisotropies in SrCu$_2$(BO$_3$)$_2$. https://doi.org/10.1103/physrevb.75.144422

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