Frequency-dependent electromagnetic properties of the Pb-doped manganite measured in the transformer-type circuit

The dependence of the transformation coefficient of the four-pole network with the toroid core made of the La0.6Pb0.4MnO3 manganite on dc biasing magnetic field and frequency was experimentally investigated. The factors which influence the value of the transmission coefficient are analyzed. In the megahertz frequency range the frequency dependence of the transformation coefficient has a resonant form with the position of the maximum and amplitude increasing with the dc biasing. The dc magnetic field dependence of the phase shift between the voltages in the primary and secondary windings was investigated. The results are interpreted taking into account the imaginary component of magnetic permeability of the core material.