Localized Doping of Epitaxial Ferrite Films

Abstract

Films of Ni_0.6Mn_0.4Fe₂O₄ epitaxially grown on the cube plane of magnesium oxide crystals have been diffusion‐doped with cobalt to change the direction of magnetization from the [111] to either the [110] or the [100]. The change in the magnetic vector direction with the small cobalt additions is a result of the extremely strong preference of cobalt ferrite to adopt a [100] easy direction while other ferrites prefer the [111]. An expression is also derived defining the critical film thickness at which the magnetic vector will move from a position making a large angle to the plane to one where the vector will lie completely in the plane.