Аннотация:Single crystal (100) and (001) TiO2 rutile plates were implanted with vanadium 40 keV ions
to the fluence of 1.5×1017 ion/cm2. A set of samples was also annealed at high-temperature in
air to restore oxygen stoichiometric content and recover the TiO2 lattice structure after the
high-dose ion implantation. In addition, a control set of TiO2 rutile plates was implanted with
40 keV argon ions to the same fluence to explore the effect of radiation-induced defects on
magnetic properties. Rutherford backscattering spectroscopy (RBS), X-ray photoelectron
spectroscopy (XPS) and vibrating sample magnetometry (VSM) measurements were carried
out to characterize the structural and magnetic properties of the vanadium-implanted TiO2.
Both as-implanted and subsequently annealed V-TiO2 samples reveal ferromagnetic response
at room temperature. Strong ferromagnetism observed in the vanadium- implanted (001) TiO2
plates is related to the substitutional V4+ ions coupled by the indirect exchange via electrons
trapped at oxygen vacancies, while much weaker ferromagnetism in the (100)-oriented plates
and the Ar-implanted samples is attributed to lattice defects induced by the high-dose ion
irradiation. Suppression of the ferromagnetic response in the vanadium-implanted (001) TiO2
after thermal treatment is explained by filling in the oxygen vacancies due to oxygen
diffusion during annealing in air atmosphere.