Effects of oxygen vacancy on impurity distribution and exchange interaction in Co-doped TiO2

Abstract

Dilute magnetic semiconductors have auracted much attention because of their potential applications in spintronics. In this paper, the effects of oxygen vacancy on total energy and magnetism in Co-doped TiO2 are investigated using the density functional theory. The energy of the system with a shorter Co-Co distance is higher than that with larger Co-Co distance after introducing oxygen vacancy. Oxygen vacancy trends to congregate around the Co cations. Moreover, the strength of exchange couple reduces in the system with a shorter Co-Co distance after introducing oxygen vacancy. For the system with a larger Co-Co distance, the exchange couple between two Co impurities is anti-ferromagnetic if oxygen vacancy is located at the basal site of octahedron containing Co, and ferromagnetic if oxygen vacancy is located at the apical site of octahedron containing Co.