Doping studies of the magnetic cobaltocuprate CoSr2Y2−xCexCu2O9±δ

A structural, magnetic and electronic study of the cobaltocuprate CoSr2Y2−xCexCu2O9±δ (image) has been performed. All materials crystallise in the orthorhombic Cmcm symmetry space group in which chains of corner linked CoO4 tetrahedra run parallel to the 1 1 0 direction. An antiferromagnetic transition is observed for image; TM increases with x. A change in the dimensionality of the magnetic order occurs at image as the interchain distance increases to a critical value. There is charge transfer between the cuprate planes and cobaltate layer as Ce doping increases, so that Co3+ is partially oxidised to Co4+ with a concomitant reduction in the valence of Cu. Superconductivity is not observed in any of the samples and a crossover from Mott to Efros and Shklovskii variable range hopping behaviour is evidenced as x increases from 0.5 to 0.8.