Magnetic lump motion in saturated ferromagnetic films

TL;DR

This paper investigates the nonlinear behavior of magnetic solitons and lumps in saturated ferromagnetic films, deriving a new model, exhibiting stable lump solutions, and analyzing their interactions and damping effects.

Contribution

A new (2+1)-dimensional asymptotic model for magnetic solitons in ferromagnetic films is derived, with exact solutions and analysis of lump stability and interactions.

Findings

Stable magnetic lumps can be generated from unstable solitons.

Lumps maintain shape and velocity during evolution and collisions.

Gilbert damping causes exponential decay of lump amplitude and velocity.

Abstract

In this paper, we study in detail the nonlinear propagation of magnetic soliton in a ferromagnetic film. The sample is magnetized to saturation by an external field perpendicular to film plane. A new generalized (2+1)-dimensional short-wave asymptotic model is derived. The bilinear-like forms of this equation are constructed, and exact magnetic line soliton solutions are exhibited. It is observed that a series of stable lumps can be generated by an unstable magnetic soliton under Gaussian disturbance. Such magnetic lumps are highly stable and can maintain their shapes and velocities during evolution or collision. The interaction between lump and magnetic soliton, as well as interaction between two lumps, are numerically investigated. We further discuss the nonlinear motion of lumps in ferrites with Gilbert-damping and inhomogeneous exchange effects. The results show that the Gilbert-damping effects make the amplitude and velocity of the magnetic lump decay exponentially during propagation. And the shock waves are generated from a lump when quenching the strength of inhomogeneous exchange.