Strain induced ferromagnetism in Sb co-doped ZnMnO samples

We report on the effect of Sb co-doping on the structural and magnetic properties of bulk ZnMnO samples. Samples with nominal compositions Zn0.98-yMn0.02SbyO (y = 0, 0.01 and 0.03) were synthesized using a solid state reaction route at 800 deg. C. X-ray diffraction (XRD) results reveal wurtzite structure of pure ZnO without any impurity phases for compositions y = 0.0 and 0.01. On the other hand, a weak diffraction peak corresponding to the impurity phase Zn/MnSb2O6 was detected in the XRD pattern of composition y = 0.03. Energy dispersive x-ray (EDAX) results confirm the presence of all elements in the samples in the stoichiometric ratio. The M-H curve of the pure ZnMnO sample shows paramagnetic behavior, whereas M-H curves of Sb co-doped samples show room temperature ferromagnetism (RTFM) with saturated loops. Saturation magnetization (MS) and coercive field (HC) both increase with the increase in Sb doping percentage. Inverse susceptibility (1/χ) versus temperature (T) curves suggests dominant antiferromagnetic interactions in the samples which decrease with the co-doping of Sb. Based on the experimental results we conclude that the observed RTFM in Sb co-doped ZnMnO is due to defects induced by strain.