Charge confinement on the CuO2 planes in slightly overdoped YBa2CU3O7-delta and the role of metallic chains

We have probed the origin of the metallic c-axis transport in slightly over doped YBa2CU3O7-partial derivative (partial derivative approximate to 0.05) via measurements of the normal-state c-axis magnetoresistance (MR). An orb ital contribution to the transverse MR, a signature of coherent band motion , arises only from the component of the magnetic field perpendicular to the CuO chains. This result implies that the chains are primarily responsible for coherent c-axis transport in YBa2CU3O7-partial derivative and that thos e regions of the CuO2 planes not hybridized with the chains remain effectiv ely two dimensional, even in the absence of a normal-state gap.