Magnetic Properties of Zn1-xCoxO Nanoparticles.

Zn1-xCoxO nanoparticles have been synthesized at various concentrations of Co2+ doping (0.005 ≤ x ≥ 0.15) by wet chemical method. Particle size was ranging from 34 – 45 nm. The magnetic moment increases from x = 0.005 and 0.01 sample to x = 0.04 sample drastically showing a value of magnetic moment as high as 8.54 μB/Cations and then decreases for x = 0.09 and 0.15 values of Co2+ doping. There is almost paramagnetic behaviour for x = 0.005 and 0.01 Co2+ doped samples. The x = 0.04 sample shows ferromagnetic ordering. Ferromagnetic behaviour decreases for x = 0.09 and 0.15 samples as the antiferromagnetic interaction dominates at higher Co2+ doping concentrations. To probe the source of magnetism, we have undertaken photolu-minescence studies also which revealed the presence of oxygen and Zinc vacancies along with other defects.