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

摘要

We report recent experimental results on the magnetic, magnetotransport, and magneto-optical properties of Co- and V-doped TiO2-delta 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 A center dot 2.5 A mu (B) per 3d impurity derived from macroscopic magnetic measurements for both systems, the magneto-optical response of TiO2-delta :V was at least 2 orders of magnitude weaker. The anomalous Hall effect was absent in V-doped TiO2-delta , and no appreciable magnetic moment on V impurities was found by X-ray magnetic circular dichroism (XMCD) technique in contrast to Co-doped TiO2-delta . The obtained experimental data indicate dissimilar origin of intrinsic ferromagnetism in TiO2-delta :Co and TiO2-delta :V.