Giant room temperature ferromagnetism in rutile TiO_2 implanted by Co

摘要

Giant room temperature ferromagnetism has been observed, for the first time, in the Co ion- implanted rutile TiO_2. The Co ions have been accelerated to 40 keV and implanted into TiO_2 (100) and TiO_2 (001) substrates. Both as prepared and temperature annealed samples were studied by magnetic resonance technique in the temperature range of 4-300 K. Strongly anisotropic ferromagnetic resonance (FMR) signals have been observed in the as prepared (100) and (001) TiO_2 samples. The theoretical analysis of FMR data has revealed rhombic magnetic anisotropy energy for Co-doped rutile TiO_2. The temperature annealing drastically affects the magnetic properties of the samples resulting in disappearance of the ferromagnetism and formation of paramagnetic Co~(2+) centers.