Recent results for the Landau-Lifshitz equation

TL;DR

This paper surveys recent advances in understanding the Landau-Lifshitz equation, covering well-posedness, approximations, stability of solitons, and self-similar solutions, highlighting its geometric and physical significance in ferromagnetism.

Contribution

It provides a comprehensive review of recent mathematical results on the Landau-Lifshitz equation, including new insights into approximations, stability, and singular solutions.

Findings

Analysis of the Cauchy problem for smooth and energy space solutions.

Connections between Landau-Lifshitz and Sine-Gordon and Schrödinger equations.

Results on stability and existence of solitons and self-similar solutions.

Abstract

We give a survey on some recent results concerning the Landau-Lifshitz equation, a fundamental nonlinear PDE with a strong geometric content, describing the dynamics of the magnetization in ferromagnetic materials. We revisit the Cauchy problem for the anisotropic Landau-Lifshitz equation, without dissipation, for smooth solutions, and also in the energy space in dimension one. We also examine two approximations of the Landau-Lifshitz equation given by of the Sine-Gordon equation and cubic Schr\"odinger equations, arising in certain singular limits of strong easy-plane and easy-axis anisotropy, respectively. Concerning localized solutions, we review the orbital and asymptotic stability problems for a sum of solitons in dimension one, exploiting the variational nature of the solitons in the hydrodynamical framework. Finally, we survey results concerning the existence, uniqueness and stability of self-similar solutions (expanders and shrinkers) for the isotropic Landau-Lifshitz equation with Gilbert term. Since expanders are associated with a singular initial condition with a jump discontinuity, we also review their well-posedness in spaces linked to the BMO space.