The structures, magnetism, and electronic transport properties of the semiconducting (La1+xCa1–x)CoRuO6 double perovskites (–0.25 < x < 0.25) were investigated. Lattice parameters, antisite disorder, the Néel temperature and resistivities were found to vary in a systematic manner with x. The Co-Ru antisite disorder was minimal at x = 0, showing that this disorder was driven by the mixed Co or Ru electronic states with |x| not equal to 0 rather than by La/Ca cation mixing. Hole doping (x < 0) decreased the resistivity by 2 orders of magnitude without significantly changing the magnetization, whereas electron doping (x > 0) enhanced the magnetization with little change to the resistivity, perhaps signalling the formation of magnetic clusters. LaCaCoRuO6 orders antiferromagnetically at TN = 96K, accompanied by a magnetostrictive anomaly. The Co/Ru spin structure, with a magnetic vector k = (1/2,0,1/2), cannot be determined unambiguously from neutron powder diffraction data.

Control of Antisite Disorder, Magnetism and Asymmetric Doping Effects in (La1+xCa1–x)CoRuO6 Double Perovskites. J.W.G.Bos, J.P.Attfield: Physical Review B, 2004, 69[9], 094434 (6pp)