Abstract
Abstract The investigation of the magnetic and transport properties of the oxygen deficient perovskites SrFe1−xCoxO3−δ shows that these compounds exhibit both ferromagnetism and metallicity in a wide compositional range (0≤x≤0.70). Negative magnetoresistance is evidenced for the first time in these oxides, in contrast to SrCoO3−δ. These properties are explained by superexchange interactions between cobalt and iron according to the scheme Fe3+OCo4+↔Fe4+OCo3+. This model is strongly supported by 57Fe Mossbauer measurements which show the existence of two sites at room temperature, high spin localized Fe4+ and delocalized Fe3+α sites, whereas magnetic disordering suggesting spin fluctuations is observed at 5 K as soon as cobalt is introduced into the SrFeO3 structure.
Published Version
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