Room temperature ferromagnetism of Ni doped cerium oxide single crystalline thin Films deposited by using rf magnetron sputtering

• Pure and Ni doped CeO2 thin films have been prepared using rf magnetron sputtering.
• The observed optical band gap was decreases of the Ni doped film.
• Defect peaks were increases for the doped films in the PL spectra.
• Raman spectra confirmed the Ni vibration was present in the doped film.
• Defect induced ferromagnetic nature of the Ni doped films was confirmed through VSM.

CeO2 and Ni–CeO2 thin films with cubic fluorite structure were prepared by rf magnetron sputtering. Crystallinity and optical properties of the prepared thin films were studied using X-ray diffraction, UV–vis and Photo Luminescence analysis. Vibrational and magnetic properties of the films were analysed through Raman and VSM analyses. The results from XRD and Raman spectroscopy indicate that doped Ni species were dispersed on the ceria surface. Room temperature magnetic measurements reveal paramagnetic nature of pure CeO2 thin films and ferromagnetic nature with reasonable saturation magnetisation (4.03×10−5 emu/cm3) of Ni doped CeO2 thin films. It is believed that the ferromagnetic contributions exhibited in the M–H loops originate from the absorptive oxygen on the surface rather than the oxygen vacancies in the lattice.