Effects of Oxygen Vacancy Defect on Magnetic Properties of (Ca,Mn)O Doped System

We study the (Ca, Mn)O doped system with oxygen vacancy point defects in monoxide CaO material. Using density functional theory calculation based on a generalized gradient approximation, we show that such a defect can convert the ground state from a spin glass to a ferromagnetic phase. Then, we discuss the stability of the magnetism in the (Ca, Mn)O doped system. The ferromagnetic and the disordered local moment states are also investigated and a super-exchange mechanism is proposed to explain such ferromagnetic magnetic behaviours. Based on the mean field approximation used in the elaboration of the Heisenberg model, we estimate the Curie temperature