Films of iron from 100 to 200 millimicrons thick deposited electrolytically from neutral and acid solutions of iron ammonium sulphate show a surprising magnetic hardness. At a field of 40 gauss the intensity of magnetization is from 200 to 300 c.g.s. units. No sudden increase in magnetization is found up to fields of 150 gauss. Films deposited on the initial film, using much smaller current densities than that required for the initial deposit, show the usual properties of electrolytic iron. An intensity of magnetization of 1000 is reached at 40 gauss field. The cause of the hardness of the initia1 films is not apparent. The great thickness at which it occurs in comparison with Maurain's critical thickness renders unlikely the assumption of a pure "thinness" effect. It may be due to the occluded hydrogen, though it does not seem likely that much hydrogen is occluded since (1) a heat treatment in carbon dioxide of several hours at 250°C changes the magnetic properties not at all, (2) the films are permanent in time in magnetic properties and do not rust.
Proceedings of the Iowa Academy of Science
©1926 Iowa Academy of Science, Inc.
Tyndall, E. P. T.
"Magnetic Properties of Thin Films of Iron, Electrolytically Deposited,"
Proceedings of the Iowa Academy of Science, 33(1), 248-249.
Available at: https://scholarworks.uni.edu/pias/vol33/iss1/67