Dependence of Geometric Magnetic Anisotropy in Thin Iron Films

Abstract

Thin iron films produced by vacuum deposition are observed to display a magnetic anisotropy dependent on the geometric location of the evaporating filament. A fiber axis structure is induced during the evaporation. If the direction of incidence of the metallic flux varies from a normal to the substrate this fiber axis tilts in a similar direction. As soon as the fiber axis is no longer normal to the plane of the film, magnetic anisotropy is produced. The variation of the tilt of the fiber axis correlates with and can be shown to account for the geometric dependence of the observed anisotropy. Calculations of the magnetic anisotropy expected in a film with a fiber axis structure and an anisotropic tensile stress in the plane of the film agree with the experimental observations for those films which show only rotational switching. Anisotropies of 3\ifmmode\times\else\texttimes\fi{}${10}^{4}$ ergs/${\mathrm{cm}}^{3}$ have been observed in iron films about 350 A thick prepared without the use of applied magnetic fields either during deposition or during a subsequent thermal anneal.