Overdoping effects in Bi2Sr2CaCu2O8+d : From electromagnetic to Josephson interlayer coupling

V. F. CORREA; E. E. KAUL; G. NIEVA

PHYSICAL REVIEW B - CONDENSED MATTER AND MATERIALS PHYSICS

The American Physical Society

Año: 2001 vol. 63 p. 1725051 - 1725054

0163-1829

We report a study of magnetic, structural, and transport properties of Bi2Sr2CaCu2O8+d 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 Hil and the characteristic field of the order-disorder transition of the vortex structure Hsp 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 Hsp is given by F0/lab2 (0) [lab(0) is the in-plane penetration depth at T=0 K], and (ii) with further overdoping the Josephson interlayer coupling becomes relevant, so Hsp deviates from F0/lab2 (0) and is fixed by the effective-mass anisotropy. All the results indicate an increase in the coupling between CuO2 planes with overdoping.