Magnetic Properties of Thin Films of Electrolytic Iron

Magnetization curves and hysteresis loops for electrolytic Fe films, 26.5 to 102 mμ thick.—Films of iron are made by electro-deposition on brass tubes. The thickness ranges from 26.5 to 102 millimicrons. Magnetization curves and hysteresis cycles are obtained by a magnetometric method. The films show increasing magnetic hardness with decreasing thickness. In a 150 gauss field the maximum intensity of magnetization reached is 1480 units for a thickness of 50 millimicrons. Thicker and thinner films are slightly less completely saturated. The coercive force, from $H_{\max }=150\mathrm{}$, is related to the thickness as follows: $H_c=5\mathrm{}\times \frac{{10}^6}{(89\mathrm{}\theta +2260)}$ where $\theta$ is the thickness in millimicrons. The theory of McKeehan is found adequate to explain the observed magnetic properties, which are traced to the constraint placed on the films by the cathode on which they are deposited. It is further shown that the films when demagnetized must be in a state of tension. Other considerations supporting the views cited are advanced.