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arXiv · 1808.04385

Gilbert damping phenomenology for two-sublattice magnets

Akashdeep Kamra·Roberto E. Troncoso·Wolfgang Belzig·Arne Brataas
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Abstract

We present a systematic phenomenological description of Gilbert damping in two-sublattice magnets. Our theory covers the full range of materials from ferro- via ferri- to antiferromagnets. Following a Rayleigh dissipation functional approach within a Lagrangian classical field formulation, the theory captures intra- as well as cross-sublattice terms in the Gilbert damping, parameterized by a 2$\times$2 matrix. When spin-pumping into an adjacent conductor causes dissipation, we obtain the corresponding Gilbert damping matrix in terms of the interfacial spin-mixing conductances. Our model reproduces the experimentally observed enhancement of the ferromagnetic resonance linewidth in a ferrimagnet close to its compensation temperature without requiring an increased Gilbert parameter. It also predicts new contributions to damping in an antiferromagnet and suggests the resonance linewidths as a direct probe of the sublattice asymmetry, which may stem from boundary or bulk.

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Akashdeep Kamra, Roberto E. Troncoso, Wolfgang Belzig, Arne Brataas. 2018-08-13. Gilbert damping phenomenology for two-sublattice magnets. https://doi.org/10.1103/physrevb.98.184402

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