Study of electronic structure and magnetization correlations in hydrogenated and vacuum annealed Ni doped ZnO

The influence of hydrogen and vacuum annealing on the structural, electronic, and magnetic properties of Ni-doped ZnO pellets viz. Zn0.95Ni0.05O has been investigated using x-ray diffraction (XRD), magnetization, resistance measurements, and x-ray photoelectron spectroscopy (XPS). Rietveld refinement of the XRD patterns confirms that all the polycrystalline samples possess wurtzite type hexagonal structure with no evidence of secondary phases. The superconducting quantum interference device magnetometry measurements exhibit a paramagnetic state for the as-synthesized Zn0.95Ni0.05O. However, the post annealing in H2 as well as in vacuum, drive it to a ferromagnetic state at 300 K. The obtained values of coercivity are 177 and 270 Oe, and the saturation magnetizations are 1.67 and 1.91 emu/g, respectively, for the H2 and vacuum annealed samples. Temperature dependent magnetization results show that the Curie temperatures are nearly the same (∼550 K) for both the annealed samples. Resistance of the annealed ...