Penetration of electromagnetic field through La0.75Pb0.25MnO3. Magnetic phase transition studies

Penetration of electromagnetic field into the bulk polycrystalline La0.75Pb0.25MnO3 manganite in a frequency range from 20 kHz to 10 MHz as a function of DC magnetic field in a temperature range near magnetic phase transition was studied experimentally. At low frequencies, variations of penetration coefficient are mostly determined by variations of magnetic permeability while in the megahertz frequency range they are mostly determined by magnetoresistance. At radio frequencies the dynamic magnetic susceptibility can substantially exceed unity even in a temperature range of 10-14° above the Curie temperature. This can be interpreted as confirmation of existence of a local short-range magnetic order above the Curie temperature.