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 TiO2. The Co ions have been accelerated to 40 keV and implanted into TiO2 (100) and TiO2 (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) TiO2 samples. The theoretical analysis of FMR data has revealed rhombic magnetic anisotropy energy for Co-doped rutile TiO2. The temperature annealing drastically affects the magnetic properties of the samples resulting in disappearance of the ferromagnetism and formation of paramagnetic Co2+ centers.