On the room temperature ferromagnetism in Co-doped TiO2 films

We report detailed studies of magnetization (M) as a function of magnetic field H (up to 50 kOe) and temperature T (5-380 K) in x% Co/TiO2 (rutile) films for x=1, 4, 6, 10, and 12. These films, prepared by sputtering, show room temperature ferromagnetism (RTFM). Measurements of M vs T at H=50 Oe reported here in zero-field-cooled (ZFC) and field-cooled (FC) cases show M peaking at T(p)similar or equal to30 K for 1% Co to T(p)similar or equal to125 K for 12% Co doped films whereas bifurcation of the FC and ZFC data is observed near 300 K. For T