Thermoelectric power and superconducting transition in high-temperature superconductors Dy_1-xPr_xBa₂Cu₃O₇

The thermoelectric power (S) and superconducting transition temperature (T_c) have been systematically measured for a series of Dy_1-xPr_xBa₂Cu₃O_7-d with x from 0 to 0.6. Our results show that S increases progressively with increasing x while T_c decreases. Based on the empirical relation between S and the carrier concentration (n), n has been extracted. The result shows a clear reduction of n with increasing x, with a linear relation for x > 0.15. This hole reduction is consistent with the hole-depletion model proposed by Liechtenstein and Mazin. Our T_c-n data are in a remarkable agreement with the universal parabolic T_c-n relation, demonstrating that the T_c suppression with Pr doping comes mainly from the hole-depletion effect.