Hard Magnetic Films of Iron, Cobalt, and Nickel

Abstract

Thin films of Fe, Co, and Ni were prepared by vacuum deposition. The angle of incidence was varied from 0° to 80° for the explicit purpose of changing the anisotropy and producing very high coercivities. The film thicknesses, determined interferometrically, were in the range from 100 to 4000 Å. X‐ray and electron diffraction examination revealed a highly faulted cubic structure for Fe and Ni, and a mixture of cubic and hexagonal phases for Co, with crystallite size ranging from 20 to 1000 Å. Increasing the angle of deposition from the substrate normal had a pronounced effect on the magnetic properties of the films. The maximum effect was observed in Fe, where easy‐axis coercivity exceeded 1100 Oe at angles approaching 90°, while at normal incidence it was only 20 Oe. Next was Co with maximum coercivity of 1000 Oe and Ni with maximum coercivity of 350 Oe. This order is what would be expected on the basis of shape anisotropy of elongated particles formed on account of the oblique incidence of the vapor flux. Magnetization reversal was studied by Bitter patterns and Lorentz electron microscopy.