Anisotropy of Dielectric Dispersion in ErFe₂O₄Single Crystal

Abstract

Dielectric dispersion was observed in a single crystal with the composition of ErFe 2 O 3.95 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 ε s - ε ∞ 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 -plane. 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 ErFe 2 O 4 is a polar crystal.