Enhancement in the optical and magnetic properties of ZnO:Co implanted by Gd³⁺ nanoparticles

Rare-earth metal Gadolinium (Gd³⁺) co-doped with ZnO:Cobalt (Co) nanoparticles are fabricated by simple, quick and versatile chemical precipitation technique. Structural, optical and magnetic studies have been carried out for Gd co-doped ZnO:Co nanoparticles. The structural analysis shows that Gd co-doped samples are single phase of wurtzite structure, where the average crystallite size of the samples is found to be nanometric regime. The morphology and chemical composition of the nanoparticles were studied using scanning electron microscopy and energy dispersive spectroscopy. Scanning electron microscopic study shows increase in particle size. In photoluminescence spectra, Gd co-doped samples show a remarkably prominent blue shift in UV region with that of pure ZnO with an increase in the intensity of green emission. The broad green emission due to the oxygen vacancy related to defect centers is present below the conduction band introduced by the Gd impurities in ZnO nanoparticles. When compared to the Co doped ZnO, Gd with ZnO:Co exhibits a clear ferromagnetism at room temperature with high coercivity. The unprecedented ferromagnetic property is attributed to the effective Ruderman–Kittel–Kasuya–Yosida exchanging interaction and change with dopant concentration Gd³⁺ into ZnO:Co nanoparticles. These results strongly suggest the future development of efficient luminescence and magnetic materials at normal room temperatures with Gd and Co doped ZnO nanostructures for spintronic devices.