Magnetodielectric effect in ErFeO₃ single crystals

We investigated magnetodielectric effect of orthoferrite single crystals of ErFeO₃, synthesized by the flux method using PbO flux. The canted antiferromagnetic order of Fe³⁺ moments arises below T_N ≈ 640 K and a spin reorientation transition occurs at T_SR ≈ 93 K, which accompanies the rotation of weak net magnetic moments from the c- to a-axis. As the temperature is further decreased, a long-range magnetic order of Er³⁺ spins emerges at T_Er ≈ 4 K. From our investigation of anisotropic dielectric constant meausurements, the magnetodieletric effect, described as the variation in the dielectric constant by applying external magnetic fields, is found in a broad range of temperature. Especially, the temperature dependence of dielectric constant exhibits a sharp anomaly at T_Er, as similarly observed in magnetic susceptibility along the c axis. In addition, a nonlinear variation in the isothermal dielectric constant, with a similar hysteretic behavior of the magnetic-field derivative of magnetization, is observed. The simultaneous non-linear variations of isothermal magnetization and dielectric constant below T_Er suggest the important role of magnetic rare earth ions in magnetoelectric characteristics of the orthoferrite compound.