Dielectric constant and losses in a magnetic field in RexMn1-xS solid solutions (Re = Gd, Yb)

Abstract

Polycrystalline samples GdxMn1-xS and YbxMn1-xS with a concentration x = 0.2, near the ions percolation concentration through the face-centered cubic lattice, are studied in order to determine fluctuations in the valence of the ytterbium ion on dielectric properties. Dielectric constant and dielectric losses were determined from measurements of capacitance and loss tangent in the frequency range 102–106 Hz at temperatures of 80–500 K without a magnetic field and in a magnetic field. The magnetic capacity and dielectric losses in the magnetic field of the sample were determined from the relative change in the real and imaginary parts of the dielectric constant of the sample in a magnetic field H = 12 kOe applied parallel to the capacitor plates. Dielectric losses decrease in a magnetic field. The magnetic capacity decreases by an order of magnitude in Gd0.2Mn0.8S compared to Yb0.2Mn0.8S. The dielectric constant in both compounds is described in the Debye model with the activation dependence of the relaxation time on temperature, where the activation energies differ for ytterbium and gadolinium ions.