epl draft Antisite Domains in Double Perovskite Ferromagnets: Impact on Magnetotransport and Half-metallicity

PACS 75.60.Ch – Domain walls and domain structure Abstract.- Several double perovskite materials of the form A2BB’O6 exhibit high ferromagnetic Tc, and significant low field magnetoresistance. They are also a candidate source of spin polarized electrons. The potential usefulness of these materials is, however, frustrated by mislocation of the B and B ’ ions, which do not organise themselves in the ideal alternating structure. The result is a strong dependence of physical properties on preparative conditions, reducing the magnetization and destroying the half-metallicity. We provide the first results on the impact of spatially corre-lated antisite disorder, as observed experimentally, on the ferromagnetic double perovskites. The antisite domains suppress magnetism and half-metallicity, as expected, but lead to a dramatic enhancement of the low field magnetoresistance. Double perovskite (DP) materials, of the form A2BB’O6, are of interest on account of their unusual mag-netic and transport properties [1]. In particular, some double perovskites, e.g., Sr2FeMoO6, show high ferromag-netic Tc, ∼ 420K, half-metallic behavior, and large lo