Effect of oxygen content on magnetic properties of bulk Zn0.9Co0.1O1±δ synthesized by high pressure and high temperature technique
Polycrystalline Zn0.9Co0.1O1±δ (Zn0.9Co0.1O0.9, Zn0.9Co0.1O and Zn0.9Co0.1O1.033) bulk samples have been prepared by directly adjusting the proportion of the starting materials under high pressure and high temperature. Structure analysis revealed that Co is incorporated into the lattice as Co2+ substituting Zn2+ ions, forming a wurtzite structure. Magnetization measurements clearly showed all samples in the absence of ferromagnetism and exhibit an antiferromagnetic behavior at 5 K. And the antiferromagnetic couple between Co atoms through oxygen evidenced that the magnetism is related to oxygen content. By combination of analysis, the effect of oxygen content on the nature and origin of an antiferromagnetism was investigated. This is further supported by a simple model, which shows the decrease of oxygen content decreases the chance of the antiferromagnetic super-exchange interaction. The results suggested oxygen content show no significant effect on ferromagnetic, however have a certain influence on antiferromagnetic in our Co-doped ZnO system.
KeywordsOxygen Content Co3O4 Boundary Defect Effective Magnetic Moment Paramagnetic Behavior
The authors gratefully thank Professor Eiji Takayama-Muroaachi of National Institute for Materials Science (NIMS), Japan to provide the flat-belt-type-high-pressure apparatus for the sample synthesis. This work is partially supported by Natural Science Foundation of Jiangsu Province of China (Grant No. BK20141337), the Fundamental Research Funds for the Central Universities (Grant No. KYLX_0085), and Large Equipment Grants of Southeast University, China.
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