Pressure effects on anisotropic resistivity in detwinned YBa2Cu3O7-delta: Unconventional carrier doping

We investigated pressure dependence of the in-plane, chain, and our-of-plan e resistivity of YBa2Cu3O7-delta under hydrostatic pressure P of up to 2 GP a using detwinned crystals. A dramatic decrease in all the resistive compon ents and the disappearance of rho(c)(T) upturn with P can be explained by a ssuming that applied pressure induces additional carriers in both the CuO2 planes and the CuO Chains, as is similar to the chemical doping. Therefore, the conventional model of the carrier transfer from the chains to the plan es is to be reexamined. [S0163-1829(99)50646-2].