Stability of Moving Néel Walls in Ferromagnetic Thin Films

Abstract This paper studies moving 180-degree Néel walls in ferromagnetic thin films under the reduced model for the in-plane magnetization proposed by Capella, Melcher and Otto (2007), in the case when a sufficiently weak external magnetic field is applied. It is shown that the linearization around the moving Néel wall’s phase determines a spectral problem that is a relatively bounded perturbation of the linearization around the static Néel wall, which is the solution when the external magnetic field is set to zero and which is spectrally stable. Uniform resolvent-type estimates for the linearized operator around the static wall are established in order to prove the spectral stability of the moving wall upon application of perturbation theory for linear operators. The spectral analysis is the basis to prove, in turn, both the decaying properties of the generated semigroup and the nonlinear stability of the moving Néel wall under small perturbations, in the case of a sufficiently weak external magnetic field. The stability of the static Néel wall, which was established in a companion paper (Capella et al. 2024), plays a key role to obtain the main result.