Hall Effect and Ferromagnetism of Very Thin Nickel Films

Abstract

Hall effect measurements have been used to determine the two Hall constants and the magnetic properties of nickel films less than 100 A thick at room temperature. The extraordinary Hall constant R₁ is found to be very much larger than in bulk nickel. In the thicker films, R₁ shows the resistivity dependence predicted by Karplus and Luttinger. For the thinner films, the deviation of the measured initial Hall slope from the value thus predicted is taken as a measure of the hardness of magnetization in the direction normal to the film plane. The saturation magnetization obtained in this manner, and its variation with film thickness, agree fairly well with values found by other methods. For our thinnest films the direction normal to the film plane is one of very hard magnetization.