Field effect in ferromagnetic metals

The metallic field effect (MFE) was studied in thin films of permalloy, with compositions 10% and 20% iron in nickel, as a function of the magnitude and direction of an applied magnetic field in the plane of the film. The film acts as one electrode of a parallel plate condenser, with mica as the dielectric. An ac charge applied to the film gives a small modulation of its conductance Phase, and frequency sensitive detection techniques are used to measure the changes in conductance.