Effects of Fe²⁺ substitution on magnetic and dielectric properties of CdCr₂S₄

The magnetic and dielectric properties of polycrystalline Cd_{1 - x}Fe_xCr₂S₄ (0 ≤ x ≤ 0.9) are investigated. Upon substitution of Cd by Fe, the Curie temperature (T_C) is increased while the saturation magnetization is decreased. A low doping level of Fe increases the permittivity, while a high doping level decreases the permittivity, which is explained by the internal barrier layer capacitor model. Kinks are observed in the temperature-dependent permittivity and loss tangent near T_C for the samples with x= 0.5, 0.7, 0.9, implying the existence of the magnetodielectric effect. Furthermore, with the increase of Fe content, a decrease of anomaly deviation rate induced by internal molecular field is revealed in the permittivity, while an increase is observed for the loss tangent.