Enhanced ferromagnetism in ZnGdO nanoparticles induced by Al co-doping

Dilute magnetic semiconductors with extended ferromagnetic properties are heavily sought for use in next-generation spintronic devices. In this work, we show that co-doping 3 at% Al into Zn0.44Gd0.03O0.50 nanoparticles can change their magnetic nature from weak to well-defined ferromagnetism (FM) at room temperature. X-ray diffraction (XRD), selected area electron diffraction (SAED), and Raman spectroscopy show that the Gd and Al atoms replaced the Zn atoms in the ZnO crystal lattice without forming other impurity phases. Field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) analyses of the suspensions revealed the high crystallinity and monodispersity of the 34-44 nm nanoparticles. The undoped and Gd-doped ZnO samples showed diamagnetism and weak FM, while the (Gd, Al) co-doped samples exhibited robust room temperature FM. The enhanced FM of the Zn0.44Gd0.03Al0.03O0.50 sample can be achieved by increasing the carrier concentration via Al co-doping.