Structure and Magnetism of Pure and Co-Doped TiO$_{2}$ Clusters

Anatase TiO
₂
cluster films having Co concentrations of 0, 6, and 8 at.% were produced by inert-gas condensation and investigated by TEM, AFM, XRD, and SQUID. The cluster films are all magnetically ordered from 10 to 400 K, with magnetizations of about 3 emu/cc, and exhibit perpendicular magnetic anisotropy. For 6% Co, no Co clusters or secondary phases are apparent, but the 8% samples contain Co and CoO. The magnetism of the doped and undoped samples is largely associated with oxygen vacancies which tend to form near the cluster surfaces.