Dipolar forces and stripe domain structure in ferromagnetic plates near the phase transition

Abstract

The authors discuss the domain structure in a ferromagnetic plate with strong uniaxial anisotropy in the perpendicular direction. The inclusion of dipolar interactions produces anisotropic magnetisation correlations above the ordering temperature T₀. They calculate the dependence of the width D of incipient domains on plate thickness L in the temperature region from slightly above to just below the transition temperature. They find that D approximately L^1/3 in this region, in contrast to the Kittel relation D approximately L^1/2 for stripe domains at temperatures well below T₀. At low temperatures the width of the walls is very small compared with the distance between them and so they do not interact with each other. They determine the range of validity of the Kittel theory and they use this to suggest substances upon which it might be possible to make appropriate observations.