Characterization of ferromagnetic Co-implanted rutile TiO2(110)

Co ions of energy 100 KeV and fluences between 1.25×10¹⁶ and 5.0×10¹⁶ Co⁺/cm² were implanted in single crystal TiO₂(110) substrates at temperatures of 300, 875 and 1075 K. Co depth profiles were obtained using X-ray photoelectron spectroscopy and Rutherford backscattering spectrometry. The Co diffused to a much greater depth when implanted at 1075 K compared to implantation at lower temperatures. The valence state of Co was investigated using Co K and L edge X-ray absorption near edge spectra. Although implantation at lower temperatures results in a mixture of metallic and oxidized Co, implantation at 1075 K results in no measurable Co(0) in the sample. The magnetic properties were investigated using magneto-optical Kerr-effect and vibrating sample magnetometer. The sample implanted at 1075 K shows ferromagnetic properties at room temperature.