Magnetic Properties of a Layered Cobaltite Sr1 - xYxCoO3 - δ (x=0.1)

The structure, the magnetic and magnetotransport properties of perovskite Sr0.9Y0.1CoO2.63 have been studied. The sample is shown to have a two-phase structure. The main phase has a tetragonally distorted unit cell and is described by space group I4/mmm. The broadening of the reflections with indices corresponding to doubling unit cell parameter c indicates the absence of the rigorous translation symmetry along axis c. The existence of the broadened superstructure reflection observed in the diffraction pattern at small angles at temperature lower than 400 K is explained by the existence of the monoclinic phase whose content is significantly lower than that of the tetragonal phase, but is dominant in the Sr0.8Y0.2CoO3 (-) (delta) composition. The spontaneous magnetization appears as the monoclinic phase forms. The magnetic structure is mainly G-type antiferromagnetic with magnetic moments 1.5(B) in the layers of CoO6 octahedra and 2(B) in the anion-deficit CoO4 (+) (gamma) layers. The conduction of the Sr0.9Y0.1CoO2.63 composition has a semiconducting character. The magnetoresistance is 57% in a field of 14 T at a temperature of 5 K and strongly decreases with the temperature increase.