Magnetic and dielectric properties of the Co-defective Ca3Co2-xO6 compounds

Abstract

The Ca3Co2-xO6 (x = 0, 0.02, 0.04, 0.06, 0.08, 0.1) samples were prepared by reducing the stoichiometric ratio of Co atoms. Their structure, magnetic properties, dielectric and magnetodielectric properties were investigated. XRD results show that the presence of a small number of vacancies does not change the crystalline structure. The positive Curie-Weiss temperature θ and interchain exchange constants J indicate that ferromagnetic interactions are stronger than the antiferromagnetic interactions in Co-defective Ca3Co2-xO6. The Co-vacancies could weaken the Co-Co exchange interactions, it has an obvious dilution effect on the ferromagnetic interactions within the chain. The magnetization steps move to low field accompanying the defects increase. Simultaneously, Co defects could also release part of the magnetic frustration. The competition of the released magnetic frustration and the dilution effect of the vacancies to the ferromagnetic chains and low doping concentration make the Co-defective Ca3Co2-xO6 present similar magnetic property with the parent Ca3Co2O6. At the positions of magnetic phase transition and the critical magnetic field of magnetization steps, clear dielectric anomalies can be detected. This result suggests the strong magnetodielectric coupling effect in Ca3Co2-xO6 (x = 0, 0.02, 0.04, 0.06, 0.08, 0.1) samples.