Overdoping effects in Bi2Sr2CaCu2O8+δ:: From electromagnetic to Josephson interlayer coupling -: art. no. 172505

We report a study of magnetic, structural, and transport properties of Bi2Sr2CaCu2O8+delta single crystals with different degrees of overdoping. The overdoping is achieved by high oxygen pressure (up to 190 bar) annealing. The parameters used to characterize the overdoping were the crystallographic c-axis lattice parameter and the superconducting transition temperature. The irreversibility line H-il and the characteristic field of the order-disorder transition of the vortex structure H-sp were obtained from dc magnetization with the applied magnetic field perpendicular to the CuO2 planes. The large overdoped range has two well-defined regions: (i) close to the optimal doping the interlayer coupling is mainly electromagnetic and H-sp is given by Phi (0)/lambda (2)(ab) (0) [lambda (ab)(0) is the in-plane penetration depth at T = 0 K], and (ii) with further overdoping the Josephson interlayer coupling becomes relevant, so H-sp deviates from Phi (0)/lambda (2)(ab) (0) and is fixed by the effective-mass anisotropy. All the results indicate an increase in the coupling between CuO2 planes with overdoping.