Effects of Ho-ion substitution on the magnetic properties of the Ca3Co2O6 frustrated spin-chain compound

Abstract Ho3+-ion doped spin-chain compounds Ca3Co2-xHoxO6 (x = 0, 0.05, 0.1, 0.15) were prepared by a conventional solid-state reaction method. Rietveld refinement of the X-ray diffraction patterns at room temperature confirmed the rhombohedral structure with the R 3 ¯ c space group. The results reveal that the solid solubility of the Ho element in Ca3Co2O6 is in the range of x = 0.1–0.15. Magnetic measurement suggests that with the increased Ho content: (1) the ferromagnetic transition temperature Tc and spin freezing temperature Tƒ decrease obviously; (2) the ferrimagnetic configuration becomes less stable; (3) the dynamic characteristics become slower; and (4) the antiferromagnetic (AFM) interaction enhances gradually. Based on these phenomena, the mechanism was discussed in detail. The magnetic correlation length is broken at a low Ho3+-ion level, and the Ho3+-ion pair formation along the chain with a high level of doping was interpreted.