Spin-Dynamical Analysis of Supercell Spin Configurations

Andrew L. Goodwin; Martin T. Dove; Matthew G. Tucker; David A. Keen

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Spin-Dynamical Analysis of Supercell Spin Configurations

Andrew L. Goodwin·Martin T. Dove·Matthew G. Tucker·David A. Keen

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Abstract

A model-independent approach capable of extracting spin-wave frequencies and displacement vectors from ensembles of supercell spin configurations is presented. The method is appropriate for those systems whose spin-dynamical motion is well characterised by small-amplitude fluctuations that give harmonic spin waves. First, the the spin-dynamical matrix is described and its eigenvalues shown to correspond to the spin-wave mode frequencies. The generalised spin coordinate matrix - a quantity that may be calculated from the observed spin orientations in an ensemble of spin configurations - is then introduced and its relationship to the spin-dynamical matrix established. Its eigenvalues are subsequently shown to be related to the spin-wave mode frequencies, allowing the extraction of spin-wave dispersion curves from configurational ensembles. Finally, a quantum-mechanical derivation of the same results is given, and the method applied as a case study to spin Monte-Carlo configurations of a 3D Heisenberg ferromagnet.

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Andrew L. Goodwin, Martin T. Dove, Matthew G. Tucker, David A. Keen. 2006-06-15. Spin-Dynamical Analysis of Supercell Spin Configurations. https://arxiv.org/abs/cond-mat/0601559

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