Ferromagnetic ordering in Co-Sm co-doped ZnO prismoids grown by co-precipitation method

Abstract

• Co-precipitation method is used to synthesize Co-Sm co-doped ZnO sample. • The crystallinity of the sample enhanced on adding Co dopant into ZnO matrix. • Prismoid structure is observed for CZ and CSZ1 samples. • CSZ1 sample showed strong superparamagnetic with weak ferromagnetic ordering. The current study illustrates the impact of defects on magnetic behaviour of the ZnO based samples. We examined the structural, luminescent, and magnetic properties of Co-Sm co-doped ZnO nano powder synthesized using the co-precipitation method. X-ray diffraction (XRD) and a Raman study were carried to understand the structural properties. The XRD results showed that all the prepared samples exhibited wurtzite phase with no impurity peaks. The same was reflected in the Raman study along with disorder induced band indicating enhanced defects sites on doping and co-doping. The presence of defects in the prepared samples was further confirmed using photoluminescence characterization. The morphological study confirms the prismoid structures in Co doped, and Co and Sm co-doped ZnO samples. A vibrating sample magnetometer (VSM) was used to investigate the magnetic properties of the samples at room temperature, which showed the coexistence of superparamagnetic and weak ferromagnetic ordering in doped/co-doped samples. The formation of defects in prismoid structures enhanced the magnetic behaviour of the samples. The evolution of ferromagnetic ordering in doped/co-doped samples due to defect states was discussed in detail.