Ab initio study of the electronic structure of Sr_2FeMoO_6 double perovskites presenting oxygen vacancies or/and antisite imperfections

摘要

Electronic band structure calculations using the ab initio full potential linearized augmented plane wave (FLAPW) method are reported for Sr_2FeMoO_6 (SFMO) double perovskites presenting oxygen vacancies or/and antisite defects. We show that the total magnetic moment is much more reduced for structures with oxygen vacancies (approximately 2μ_B per vacancy) than for structures without. We investigate also 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. Finally, we exhibit that the half-metallic character is preserved for SFMO containing only nearly isolated oxygen vacancies.