Structural and magnetic properties of Tb implanted ZnO single crystals

ZnO single crystals have been implanted with Tb ions. For an atomic concentration of 1.5%, annealing at 823 K leads to an increase of the saturation magnetization per implanted Tb ion up to 1.8 μB at room temperature. Structural investigations revealed no secondary phase formation, but the out-diffusion of Tb. No significant evidence is found for Tb substituting Zn sites either in the as-implanted or annealed samples. However, indications for the existence of a small amount of Tb nanoclusters however have been found using magnetization versus temperature measurements. The ferromagnetic properties disappear completely upon annealing at 1023 K. This behavior is related to the formation of oxide complexes or nanoparticles.