Energy gap and defects engineered optical, and magnetic properties of ZnO-based diluted magnetic semiconducting nanoparticles

Diluted magnetic semiconducting nanostructures are attractive materials for spintronics applications. This study focuses on the fabrication of (Gd, Fe) co-doped ZnO nanoparticles (NPs). X-ray diffractogram analysis confirms a monophase hexagonal wurtzite structure, matching JCPDS file number (36–1451). The Scherrer equation and Williamson-Hall plot are used to measure crystal size and strain, respectively. Scanning electron microscopy reveals a spherical surface morphology, and energy-dispersive X-ray analysis confirms elemental composition. Transmission electron microscopy shows average diameter of 17–52 nm and fringe spaces of 0.269–0.245 nm. The incorporation of dopant ions leads to a slight reduction in the bandgap. The Fe3+ and Gd3+ oxidation states of the dopant elements are confirmed using X-ray photoelectron spectroscopy. Functional groups are identified via Fourier transform spectroscopy, and structural defects are identified by photoluminescence analysis. Pristine ZnO NPs exhibit diamagnetic behavior, while the doped samples demonstrate ferromagnetic properties. The observed ferromagnetism in the doped NPs is attributed to bound magnetic polaron interactions. Electron paramagnetic resonance spectroscopy detects unpaired electrons in samples, with g factor values of approximately 2. The co-doping of Gd and Fe presents a promising approach for achieving ferromagnetism in ZnO systems, offering significant potential for advancement in spintronics technology.