Effect of oxygen vacancy concentration on the absorption spectra of Dy2Ti2O7 crystal

Dy2Ti2O7 (DTO) crystal with magneto-optical effect has been grown by Czochralski method. Two DTO wafers with different oxygen vacancy concentrations were prepared by annealing in oxygen or ammonia atmospheres. The effect of oxygen vacancy concentration on the absorption spectra of DTO crystal was investigated by first-principles calculation based on the density functional theory. It is found that the absorption loss of DTO annealed in oxygen atmosphere is about twice as high as that of DTO annealed in ammonia atmosphere in the wavelength of 380-580 nm at room temperature. Based on their identical Faraday rotation angle, the magneto-optical figures of merit of DTO annealed in ammonia atmosphere are about twice as large as that of DTO in oxygen atmosphere in the 380-580 nm range. The corresponding results reveal that oxygen vacancy concentration plays a significant role in the absorption spectra of DTO crystal, and DTO with high oxygen vacancy concentration may be a promising material for magneto-optical devices especially in the 400-700 nm range.