Preparation of Dilute Magnetic Oxide Thin Films by Reactive-Biased Target-Ion Beam-Sputter Deposition

We have used reactive-biased target-ion beam-sputter deposition to prepare Co$_{x}$Ti$_{1-x}$O$_{2 }$thin films on LaAlO$_{3}$ (100) and SrTiO$_{3 }$(100) substrates for \textit{0.005$<$x$<$0.06}. The influence of the growth parameters on the microstructure, magnetic and transport properties of Co$_{x}$Ti$_{1-x}$O$_{2 }$was systematically investigated. Both pure anatase phase and mixed anatase/rutile phases of TiO$_{2}$ films were obtained by varying the growth conditions and subsequently demonstrated different magnetic and transport properties. All samples show a curie temperature higher than 300 K. The pure anatase Co$_{x}$Ti$_{1-x}$O$_{2 }$thin films have saturated magnetic moments of 1$\sim $2 $\mu _{B}$/Co at 10 K. The presence of rutile phase seems to greatly enhance the moments at lower temperatures.