Structure, magnetic and magnetic transport properties of layered cobaltite Sr0.9Y0.1CoO2.63

Abstract

The structure, magnetic and magnetotransport properties of perovskite Sr_0.9Y_0.1CoO_2.63 are studied. It is shown that the sample is structurally two-phase. The main phase has a tetragonal-distorted unit cell and is described by the spatial group I4/mmm. The broadening of the reflexes with indexes corresponding to a doubling of the parameter from the unit cell indicates that there is no strict translational symmetry along the с-axis. The presence of a broadened superstructural reflex observed at small angles on X-ray diffraction patterns at temperatures below 400 K is due to the monoclinic phase, whose content is much smaller than the tetragonal phase. Spontaneous magnetization appears during the formation of the monoclinic phase. The magnetic structure is predominantly an antiferromagnetic G-type structure with magnetic moments of 1.5µ_B in the layers of CoO₆ octahedra and 2µ_B in the anion-deficient CoO_4+γ layers. The electrical conductivity of Sr_0.9Y_0.1CoO_2.63 has a semiconductor in character. The magnetoresistance reaches 57 % in a field of 14 T at a temperature of 5 K and decreases strongly with increasing temperature.