Enhancement of ferromagnetism in C ion implanted CeO2 thin films

Abstract

This investigation reports on room temperature ferromagnetism in pristine and C ion implanted CeO2 thin films deposited on Si (111) substrates by the radio frequency (RF)-sputtering method. X-ray diffraction analysis shows that the face-centered cubic (FCC) structure corresponds to CeO2. The Raman spectra further confirm the formation of phase and also indicate the presence of defects, mainly oxygen vacancies, in these films. The presence of C is evident from Rutherford backscattering studies. Atomic force microscopy images indicate that the surface roughness values of the films reduce after C ion implantation. It is observed that the magnetic properties in CeO2 thin films are enhanced by C ion implantation. The saturation magnetization of the pristine film increases from ∼7 emu cm−3 to ∼27 emu cm−3 for a fluence of 6 × 1016 ions cm−2. It is also observed that the coercivity values change after C ion implantation and reduce for a film with an ion fluence of 6 × 1016 ions cm−2 compared with other films. Mechanisms such as the F-center exchange (FCE) model are considered when attempting to understand the enhanced ferromagnetism of C ion implanted CeO2 thin films.