ANISOTROPY OF DIELECTRIC-DISPERSION IN ERFE2O4 SINGLE-CRYSTAL

Dielectric dispersion was observed in a single crystal with the composition of ErFe2O3.95, below magnetic transition temperature. It is characterized by a large dielectric constant of the order of 10(4), and a Debye-type frequency dependence like in the polycrystalline samples of the same substance which we reported in a previous paper. Large anisotropy exists in the strength epsilon S - epsilon(infinity) and the characteristic relaxation frequency of the dispersion. The strength is higher within the c-plane than along the c-axis, while the characteristic frequency is much larger along the c-axis than within the c-pIane. The dielectric dispersion in the polycrystalline sample cannot be explained by a simple average of the single crystal results. The observed dispersion is qualitatively discussed with a model of domain wall motion on an assumption that ErFe2O4 is a polar crystal.