20 December 2006 Structural and magnetic properties of cobalt implanted TiO2 thin films
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We experimentally investigate the room temperature ferromagnetism (RTFM) observed in Co implanted anatase TiO2 thin films. TiO2 thin films were prepared by RF sputtering onto thermally grown oxide layers on Si substrates. Cobalt implantation was performed using a metal vapor vacuum arc ion source at an implant dose of 4 x1016 cm-2. Post annealing was performed in a vacuum chamber at various temperatures up to 700°C for 2 or 4 hours. Characterization of these films as-implanted and after thermal annealing under various conditions was performed using Rutherford backscattering spectrometry, transmission electron microscopy, x-ray diffractometry and vibrating sample magnetometry. Clear RTFM properties were observed in all samples. The MS value showed a general increase trend with increasing annealing time with higher values at higher annealing temperatures. Quite a number of samples showed Ms values exceeding the bulk Co value of 1.69μB/Co atom after annealing. The maximum MS value observed is about 3.16μB/Co atom for the sample annealed at 700°C for 4 hours. Such high MS values indicate that the RTFM must not come from Co clusters alone. Possible origins of the RTFM properties are discussed in conjunction with the structural properties.
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W. Y. Luk, W. Y. Luk, S. P. Wong, S. P. Wong, N. Ke, N. Ke, Q. Li, Q. Li, J. K. N. Lindner, J. K. N. Lindner, } "Structural and magnetic properties of cobalt implanted TiO2 thin films", Proc. SPIE 6415, Micro- and Nanotechnology: Materials, Processes, Packaging, and Systems III, 64150M (20 December 2006); doi: 10.1117/12.695191; https://doi.org/10.1117/12.695191

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