Impedance Spectroscopy of Fe Nanofilms Grown in a Magnetic Field on Gd2O3 and Glass

The frequency characteristics of impedance, phase difference between current and voltage, hodographs, and corresponding equivalent circuits of Fe nanofilms grown in a constant magnetic field on Gd2O3 and silicate glass substrates are investigated. It is shown that with increasing magnetic field strength from 40 E to 1200 E, the morphology of Fe films changes from labyrinthine to continuous, consisting of coalesced iron islands. This complex morphology of the films is the source of the induction and capacitance components of the imaginary part of the impedance. It was found that at a frequency of 630 Hz, a consistent electrical resonance is observed in Fe films, as well as a minimum value of the total impedance. At frequencies above 104 Hz, a sharp change in the impedance components and phase difference is observed in Fe films, which is probably due to the peculiarities of the film morphology. The Nyquist hodographs were constructed and the parameters of the corresponding equivalent circuits were calculated using the ZView computer program. It is shown that both the equivalent schemes of the hodographs and the peculiarities of the frequency dependence of the impedance and phase difference components depend largely on the morphology of the films, which is determined by the elasticity of the magnetic field applied during their growth, as well as by the chemical composition of the substrates. Gd2O3 substrates affect Fe films due to the d-f exchange interaction between the unfilled f and d electron shells of the atoms that make up the Gd2O3 and Fe layers. Silicate glass has an effect due to the ions of technological impurities contained in its composition, which can act as traps for electrons passing through the Fe film.