Magnetic properties of Co-doped ZnO prepared by sol–gel method

Zn1−xCoxO (0 < x ≤ 0.09) were prepared by sol–gel method. The structure and magnetism analysis indicate that Co2+ ions substitute for Zn2+ ions to form a solid solution with wurtzite structure of ZnO. Zn1−xCoxO (0.03 ≤ x ≤ 0.09) are paramagnetic at 300 K, but ferromagnetic component seems to exists in the Zn1−xCoxO (x = 0.01 and 0.02). Low-temperature (about 150 K) ferromagnetism is found in Zn1−xCoxO (0 < x ≤ 0.09). Both maximum moment/Co at 80 K and the phase-transition temperature (Curie temperature) decrease with the increase of Co content. This magnetic phenomenon can be understood in the framework of the mean-field Zener model.