Hg,Re-1223 system: T-c dependence on hydrostatic pressure and thermopower measurements

Samples of Hg1-xRexBa2Ca2Cu3O8+delta superconductor (Hg,Re-1223) were prepa red with varying rhenium (Re) nominal content (0.15 less than or equal to x less than or equal to 0.20) in order to study the changes on the critical temperature under external hydrostatic pressure. At low pressures the delta T(c)/deltaP depends strongly on the Re doping and the sample with x = 0.18 shows the largest measured value. However. thermopower measurements reveal that there is no significant change in the numbers of carriers for the diff erent Re content (0.15 less than or equal to x less than or equal to 0.20) meaning that deltaT(c)/deltan is the same for all samples which, in princip le, have an optimal oxygen content. Taking into account that dT(c)/dP = del taT(c)(i)/deltaP + [deltaT(c)/deltan] [deltan/deltaP] and deltaT(c)/deltan does not depend on the Re content we can argue that the intrinsic term (del taT(c)(i)/deltaP) determines the influence of external hydrostatic pressure on T-c. (C) 2001 Elsevier Science B.V. All rights reserved.