Search

In this work the study of the ferromagnetic resonance (FMR) and of the electrical conductivity in the perovskite sample, Sr[SUB2]FeMoO[SUB6], is presented. The sample has been manufactured by conventional ceramic method sintering in inert gas atmosphere. Electrical conductivity, of about 1000-1200 S/m, has been measured in the 125-300 K temperature range. FMR linewidths have been measured at 9.48 GHz from 125 to 300 K. A decrease of the linewidth with increasing temperature has been obtained. This behavior has been attributed to the presence of valence exchange mechanism, which takes places in samples with Fe[SUP2+] cations. In this way, FMR linewidth analysis has been revealed like a useful and clear technique in determining the cation distribution of the sample showing the presence of Fe[SUP2+] ions. This technique has also shown data about the microstructure of the sintered polycrystalline sample finding the porosity value of the sample. [ABSTRACT FROM AUTHOR]

The analysis of the induced current distribution in conducting wires subjected to a harmonic axial voltage is important in designing many electrical devices such as transformers and transmission lines. The azimuthal magnetic field induces axial electric currents and therefore the impedance of the wire depends on the excitation frequency. The current density is increasingly confined to a thin layer at the boundary of the wire as the frequency increases. To minimize this effect at higher frequencies it is necessary to enhance the surface-to-volume ratio by using thin high-conductivity wires. The study of induction phenomena in conducting samples subjected to a harmonic longitudinal magnetic field has attracted less attention. The time-varying magnetic flux induces eddy currents, which flow perpendicularly to the axis of the sample. We study the electromagnetic field in samples of simple geometry, making the usual approximations in good conductors. The validity of our calculations extends to several GHz and allows us to propose a method for determining the electrical conductivity by measuring the phase angle of the complex mutual inductance between a primary coil, responsible for the external magnetic field, and a secondary winding around the sample. [ABSTRACT FROM AUTHOR]

In this paper, we present a precise technique for contactless measurement of resistivity in conductive tubes. The method is simply based on the determination of the phase angle of the complex mutual inductance between two coils working under low-frequency conditions. The first coil is placed around the tube, whereas the detecting coil is situated inside it. Study of the magnetic screening caused by the currents induced in the tube allows its conductivity to be determined. The use of low frequency guarantees the almost complete absence of the skin effect in such a way that the results are obtained in a very simple manner. [ABSTRACT FROM AUTHOR]