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arXiv · 1705.08146

The Sine-Gordon regime of the Landau-Lifshitz equation with a strong easy-plane anisotropy

André de Laire·Philippe Gravejat
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Abstract

It is well-known that the dynamics of biaxial ferromagnets with a strong easy-plane anisotropy is essentially governed by the Sine-Gordon equation. In this paper, we provide a rigorous justification to this observation. More precisely, we show the convergence of the solutions to the Landau-Lifshitz equation for biaxial ferromagnets towards the solutions to the Sine-Gordon equation in the regime of a strong easy-plane anisotropy. Moreover, we establish the sharpness of our convergence result. This result holds for solutions to the Landau-Lifshitz equation in high order Sobolev spaces. We first provide an alternative proof for local well-posedness in this setting by introducing high order energy quantities with better symmetrization properties. We then derive the convergence from the consistency of the Landau-Lifshitz equation with the Sine-Gordon equation by using well-tailored energy estimates. As a by-product, we also obtain a further derivation of the free wave regime of the Landau-Lifshitz equation.

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André de Laire, Philippe Gravejat. 2017-05-23. The Sine-Gordon regime of the Landau-Lifshitz equation with a strong easy-plane anisotropy. https://arxiv.org/abs/1705.08146

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