Annealing influence on the exchange stiffness constant of Permalloy films with stripe domains

Abstract

An investigation of the annealing influence on the stripe domains structure in Permalloy films has been performed by comparing the static and dynamic magnetic properties. An increasing exchange stiffness constant Aex is found when the annealing temperature rises. The magnetic force microscopy images show that the width of stripe domain increases with the increase of annealing temperature, and the increasing exchange stiffness constant is considered to be the most prominent reason. A perpendicular standing spin-wave model is used to deduce the Aex from the evolution of resonance frequencies, and the Aex increases nearly twice from 7.2 × 10-7 ergs cm-1 for the as-deposited film to 12.9 × 10-7 ergs cm-1 for the film annealing at 400 °C. Micromagnetic calculation is also used to compute the magnetization configuration, and the results agree well with the experimental conclusions.