Oxygen vacancies or/and antisite imperfections in Sr2FeMoO6 double perovskites:: an ab initio investigation

We report on electronic band structure calculations, using the ab initio full potential linearized augmented plane wave (FLAPW) method, for Sr2FeMoO6 (SFMO) double perovskites presenting antisite defects or/and oxygen vacancies. We exhibit that the half-metallic character is preserved for SFMO containing only nearly isolated oxygen vacancies, indicating that the control of oxygen content in such compounds is less critical for the transport properties than the control of the antisite defects. We show that the total magnetic moment is much more reduced for structures with oxygen vacancies (approximately 2 mu(B) per vacancy) than for structures without. We also investigate the stability of an antiparallel (AP) magnetic moment on Fe antisites and we show that these solutions are highly unstable relative to the parallel (P) solution, even if the presence of O vacancies reduces the difference between P and AP solutions.