The structure and weak ferromagnetism of the double layered cuprocobaltate: Y2SrCu0.6Co1.4O6.5

Rietveld refinement of the X-ray powder diffraction (XRPD) pattern confirms that Y2SrCu0.6Co1.4O6.5 is isostructural to Y2SrCuFeO6.5. Unlike its Fe-an alog which is antiferromagnetic, Y2SrCu0.6Co1.4O6.5 behaves as a three-dime nsional (3D) ferromagnet below T-C = 385 It with a spontaneous magnetic mom ent per formula unit of only mu(s) = 0.07 mu(B) extrapolated to T = 0 K, We concluded that this weak ferromagnetism (WFM) originates from Dzyaloshinsk y-Moriya (D-M) spin canting mechanism based on the observation of T-2 depen dence of the low-temperature magnetization, The electrical resistance of si ntered samples shows an exponential dependence on temperature exp(T-0/T)(al pha) with alpha = 1/2 in the 185-570 Ii temperature range, which indicates the conduction mechanism is within variable range hopping (VRH) regime with long-range Coulomb interaction between the carriers, Y2SrCu0.6Co1.4O6.5 do es not show any significant magneto-resistance effect in the 200-400 K temp erature range, (C) 1999 Academic Press.