Above Room Temperature Ferromagnetism in Co- and V-Doped TiO2 — Revealing the Different Contributions of Defects and Impurities

We report recent experimental results on themagnetic, magnetotransport, and magneto-optical properties of Co- and V-doped TiO2−δ magnetic oxides at the doping level around 1 at. %. The samples were prepared using rf magnetron sputtering in identical conditions that allows to compare the mechanisms of above-room-temperature ferromagnetism observed in both cases of doping. In spite of the comparable values of magnetic moment around 1 ÷ 2.5 μB per 3d impurity derived from macroscopic magnetic measurements for both systems, the magneto-optical response of TiO2−δ :V was at least 2 orders of magnitude weaker. The anomalous Hall effect was absent in V-doped TiO2−δ, and no appreciable magnetic moment on V impurities was found by X-ray magnetic circular dichroism (XMCD) technique in contrast to Co-doped TiO2−δ. The obtained experimental data indicate dissimilar origin of intrinsic ferromagnetismin TiO2−δ:Co and TiO2−δ:V.