Thin magnetic films of Co‐P were prepared in two somewhat different electroless cobalt solutions. The magnetic properties and the corrosion behavior of these films as a function of thickness was studied. The films exhibited high coercivities with a maximum of about 1000 oe at a thickness of 600Aå. The magnetic moment of these films was found to decrease on exposure to high humidity and moderate temperatures (40°–70°C); this was used as a means of studying the extent of corrosion. The extent of corrosion was found to vary as the 2/3 power of the thickness of the film.

Samples of electroless cobalt phosphorus films of various thickness in the region less than 3000Aå were prepared from solutions containing different concentrations of hypophosphite ion. These samples were analyzed by x‐ray fluorescence and their magnetic characteristics were studied. The per cent phosphorus in the films was found to increase approximately logarithmically as the concentration of hypophosphite was increased. The plating rate increased concomitantly. The saturation magnetic moment and the coercivity were found to depend strongly on the phosphorus content of the films. The coercivities of these films also have a strong dependence on thickness. To a large extent the interaction of these two physical properties of the film determine the magnetic properties observed.

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 A. 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 A. Increasing the angle of