Doping dependence of magnetic and transport properties in single crystalline Co-doped BaFe2As2

We report the doping dependence of transport and magnetic properties in Co-doped BaFe2As2. With increasing Co concentration x, structural and magnetic transitions are suppressed and superconductivity emerges in the range of 0.3 < x < 0.15. T-linear resistivity is observed at the optimally doped composition x = 0.075 and the temperature exponent of the resistivity increases with x. Critical current density J(c) at low temperatures and low fields obtained from bulk magnetization is reasonably large and the doping dependence shows a maximum at x similar to 0.07 similar to T-c. The values of J(c) at low temperatures reach about 1 x 10(6) A/cm(2) around the optimally doped region, which is potentially attractive for technological applications. (c) 2009 Published by Elsevier B.V.