Effect of nonmagnetic substitution on the magnetic correlation of the frustrated Ca3CoMn1-xGaxO6 (0≤x≤0.2)

Abstract

For the spin-chain compound Ca3CoMnO6, the perfect Co/Mn ionic order causes the lost of ↑↑↓↓ long-range antiferromagnetic order. The lost long-range magnetic order results in the emergence of short range magnetic correlation interaction, forming the so called “order by disorder” phenomenon. In present paper, nonmagnetic Ga3+-doped Ca3CoMn1-xGaxO6 compounds were prepared. The influence of Ga3+ substitution on the structure and magnetic order of Ca3CoMn1-xGaxO6 were investigated. It is found that the solid solubility of Ga3+ cation in Ca3CoMn1-xGaxO6 is 0.2 < x < 0.3. With introducing of Ga3+ cation, the oxidation state of some Co cations changes from Co2+ to Co3+. Magnetization measurements reveal that doped with nonmagnetic Ga3+ weakens the formation of short range magnetic order and enhances the antiferromagnetic transition temperature. As a result, more robust long rang antiferromagnetic order is established and the transition field that causes the ↑↑↓↓ spin state of Co–Mn–Co–Mn chain to ↑↑↓↑ state increases obviously. Meanwhile, the shortened short range magnetic correlation in Ga3+ doped Ca3CoMn1-xGaxO6 can be driven more easily by the thermal activation energy and a quicker dynamic behavior was observed in time windows.