Ferromagnetism in Co-Doped TiO2 Rutile Thin Films Grown by Laser Molecular Beam Epitaxy

Epitaxial TiO2 rutile films were fabricated on α-Al2O3 (1012) substrate in the layer-by-layer fashion by laser molecular beam epitaxy. Ablation with a Co-doped TiO2 target produced single phase of rutile film with the concentration of Co between 0 and 5%. Some ferromagnetic domain structures were observed in Co x Ti1-x O2 rutile films by a scanning superconducting quantum interference device microscope at 3 to 90 K. The magnetic hysteresis could also be observed even at room temperature with a magnetic moment of ∼ 1 µB/Co atom.