Fabrication and characterization of nano-structured ferromagnetic Ti1-xFexO2 thin films
R. Apetrei, C. Negrila, D. Macovei, V. Dascaleanu, C.M. Teodorescu, D. Luca
Alexandru Ioan Cuza University, RO
Keywords: Ti1-xFexO2 films, ferromagnetism, oxygen vacancy, EXAFS/XANES
Abstract:Ti1-xFexO2, 300 nm thin films with x ranging between 0.0 and 0.6, have been fabricated by RF magnetron sputtering. Specimen characterization was done by XPS, AFM, XRD,UV-Vis spectrometry, MOKE, and XANES/EXAFS techniques. The AFM and XPS depth-profiling data showed that the films feature very smooth interfaces, while the XRD data showed the presence of nano-sized anatase ordered domains spread in a Fe-rich amorphous phase. An oxygen depletion is evident in the films, due to preparation conditions and the heavy doping, which finally results in the alteration of the electronic properties of the materials. This phenomenon was further demonstrated by the red shift in the optical transmittance data and the changes in the MOKE signal. The results are discussed in relation with the chemical reactivity and the alterations of atomic environment, as demonstrated by the XANES/EXAFS data. A close correlation between the activation of the oxygen vacancy processes in the initial anatase-ordered domains and the ferromagnetic properties of the films has been found.