Effects of single O vacancy on the magnetism and electronic structure of Ti doped CoO: A first principle study

The electronic structure and magnetism of Co₁₄Ti₂O₁₅ systems are investigated by first-principles calculations. CoO is an antiferromagnetic insulator. The Ti doped CoO at positions 9 and 11 shows a half-metallic character. The O vacancy near Ti has a great effect on Ti magnetic moment due to the electron transfer. When the O vacancy at position 6 or 9, the Ti magnetic moment is very small and the systems are magnetic insulator. As the O vacancy locates at position 1, the Ti magnetic moment is smaller than that in Co₁₄Ti₂O₁₆ system, showing a metallic character that makes its conductivity enhanced. The system with O vacancy at position 2 shows a half-metallic character due to the strong hybridization between Ti and Co atoms. The system with O vacancy at position 5 shows a metallic character; the system with O vacancy at position 13 or 14 shows a half-metallic character. - Highlights: • When the O vacancies at 6 position and 9, the systems are magnetic insulator. • The system with O vacancy at position 5 shows the metallic characteristic. • The system with O vacancy at position 2, 13 or 14 shows a half-metallic character