Diluted ferromagnetic properties in Fe- and Co-doped TiO/sub 2-/spl delta// thin films

Abstract

Magnetic and electronic properties of Fe- and Co-doped TiO/sub 2-/spl delta// thin films are investigated by vibrating sample magnetometer (VSM), Mossbauer spectroscopy, and X-ray photoelectron spectroscopy (XPS). When the precursor films are annealed in vacuum, the resulting oxygen-deficient TiO/sub 2-/spl delta//:Fe and TiO/sub 2-/spl delta//:Co films are found to become semiconducting with p-type carriers in the 10/sup 18/ cm/sup -3/ range. The oxygen-deficient films go through conductivity transitions from n-type to p-type by Fe and Co doping. Results of VSM measurements show that ferromagnetism is exhibited at room temperature. XPS measurements on the thin films reveal that Fe ions have both Fe/sup 2+/ and Fe/sup 3+/ ionic valences while Co ions have Co/sup 2+/ mostly. Also, the density of Fe/sup 2+/ ions is found to decrease after annealing.