PRESSURE EFFECT ON THE SUPERCONDUCTING TRANSITION-TEMPERATURE OF DY1-XPRXBA2CU3O7-DELTA

The pressure effect on the superconducting transition temperature (dT( c)/dP) has been measured for Dy1-xPrxBa2Cu3O7-delta with x = 0, 0.02, 0.05, 0.1, 0.15, 0.2, and 0.3. Although the T(c) suppression by Pr is in a different fashion for Y1-xPrxBa2Cu3O7-delta and Dy1-xPrxBa2Cu3O7- delta, the dT(c)/dP is similar in these two systems, with respect to x . The measured dT(c)/dP is positive at small x but becomes negative fo r x > 0.2 which is associated with the pressure effect on the normal-s tate resistivity (I/R) (dR/dP). The positive (1/R) (dR/dP) at x > 0.2 indicates that the number of carriers is decreasing under pressure and it supports the picture of hole localization through the hybridizatio n of Pr-4f and 0-2p bands. The mechanical pressure has a negative effe ct on T(c) for x > 0. 2, but chemical pressure has a positive effect o n T(c) according to the results of chemical substitution. This suggest s that the large R (= rare earth element) may possibly reduce the Pr-O distance, and increase the hybridization of Pr-4f and 0-2p bands.