6533b839fe1ef96bd12a6e0c

RESEARCH PRODUCT

Substitution Effects in Double Perovskites: How the Crystal Structure Influences the Electronic Properties

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We systematically studied substituted Sr2FeReO6 with respect to experimental characterization and theoretical band structure calculations. In the framework of the tight-binding approach, hole- or electron-doping of Sr2MM’O6 were performed at the M or M’ positions either by transition or main group metals. Hole-doping, rather than electron-doping, has a favorable effect to improve the half-metallicity (Curie temperature and saturation magnetization) of the parent compound. When M is substituted by another metal, the original M’ metal will serve as a redox buffer (and vice versa). Substituting M by another metal with a size similar to that of the metal at M’ position causes disorder, which has high impact on the properties of the starting compound. Main group metals block the super-exchange pathways that underlie the half-metallic properties in Sr2FeReO6. Thus a Mott-insulating and spin-frustrated state is produced in an ordered phase due to the geometrical arrangement, e.g. in Sr2InReO6. However, M/M’ disorder is significant in the main group elements containing double perovskites, this triggers electronic conductivity arising from electron hopping from Re to adjacent Re ions as observed in Sr2GaReO6.