Effect of oxygen-doping on Bi2Sr2Ca2Cu3O10 + d vortex matter: Crossover from electromagnetic to Josephson interlayer coupling

A. PIRIOU; YANINA FASANO; E. GIANNINI; /O. FISCHER

PHYSICAL REVIEW B - CONDENSED MATTER AND MATERIALS PHYSICS

American Physical Society

Año: 2008 vol. 77 p. 184508 - 184514

0163-1829

We study the effect of oxygen-doping on the critical temperature Tc, the vortex matter phase diagram, and the nature of the coupling mechanism between the Cu-O layers in the three-layer Bi2Sr2Ca2Cu3O10+δ (Bi-2223) compound. Contrary to previous reports, in the overdoped (OD) regime, we do find a variation in Tc by increasing the oxygen partial pressure of the postannealing treatment. This variation is less significant than in the bilayer compound Bi2Sr2CaCu2O10+δ (Bi-2212) and does not follow the universal Tc vs δ relation. Magnetic measurements reveal that increasing δ enlarges the field and temperature stability of the Bragg glass phase. These findings imply that the interlayer coupling between Cu-O layers enhances with δ. The anisotropy parameter estimated from directional first-penetration field measurements monotonously decreases from 50 in the underdoped (UD) to 15 in the OD regimes. However, the in-plane penetration depth presents a boomerang-type behavior with δ, reaching its minimum value close to optimal doping. These two facts lead to a crossover from a Josephson OD to electromagnetic UD-dominated coupling of adjacent Cu-O layers in the vicinity of optimal doping.