Magnetic phases in lanthanum–strontium manganite–cobaltite La1.25Sr0.75MnCoO6

Abstract Two methods—the solid-phase high-temperature (1300 °C) and the liquid-phase low-temperature (750 °C) routes—were used to synthesize the complex oxide La 1.25 Sr 0.75 MnCoO 6 , which has the structure of rhombohedral perovskite and is characterized by a disordered distribution of Mn and Co in structural sites. It was found by means of X-ray absorption near edge spectroscopy (XANES) at the K-edge that mixed valence states of Co 2+ /Co 3+ and Mn 3+ /Mn 4+ , exist in both phases. Measurements of dc magnetization and real ( χ′ ) and imaginary ( χ″ ) parts of the ac susceptibility showed that the magnetic properties of these oxides are determined by a ferromagnetic transition at T C =217 K and a frequency-dependent transition at T g T g is indicative of the cluster-glass behavior of La 1.25 Sr 0.75 MnCoO 6 (7 5 0) at T T C within the ferromagnetic state.