Magnetic and photoconductive properties of the CoxPt1−x-Pt-TiO2 nanocomposite films prepared by reactive sputter-deposition

Co-Pt-Ti-O films were prepared on SiO2 glass substrate by sputtering of a Co-Pt-Ti composite target in Ar+O2 atmosphere with the total pressure of 4 Pa and then in situ annealed at an elevated temperature Ta to form the CoxPt1−x-TiO2 films. It is found that the ferromagnetic films grow in the form of fiber-like columnar grain about 10 nm in diameter when sputtered in the pressure ratio of O2/Ar=1/133 followed by in situ annealing at Ta≧600°C. The films contain Pt and amorphous anatase-type TiO2 phases besides the ferromagnetic fcc-CoxPt1−x phase. Thus, such nanocomposite films show photoconductive properties due to the anatase-type TiO2 phase as well as ferromagnetic properties due to the CoxPt1−x phase.