Thin Films of Ferromagnetic Materials

Experimental observations are reported on the magnetic properties of thin evaporated films of nickel. The saturation magnetization follows the general prediction of Klein and Smith after somewhat arbitrary modifications on the basis of fitting the Weiss curve for bulk specimens, as suggested by Drigo. Qualitatively observed properties due to domain structure follow the predictions of Kittle. The surface roughness of the specimens has been carefully controlled. Measurements of temperature coefficient of resistance have led to modification of the theory of electron mean free path in thin films. The mean free path is found to vary at small thicknesses, rather than remaining constant as assumed by Fuchs and Sondheimer. The surface roughness has been estimated with the help of this theory. The films of nickel behave as if surface variations extend into the film approximately 3 angstroms from each surface.