VARIATION OF THE AB-PLANE NORMAL-STATE RESISTANCE AND THE SUPERCONDUCTING TRANSITION-TEMPERATURE OF A YBA2CU3O7-DELTA SINGLE-CRYSTAL TO PRESSURES OF 13 GPA

The temperature-dependent dc electrical resistance of the ab plane of a twinned YBa2Cu3O7-delta single crystal with an ambient pressure T(c)(50%)approximately 90 K [DELTAT(c)(10-90%)-350 mK] has been studied to 13.2 GPa. The initial rate of increase in the critical temperature to pressures of approximately 6 GPa is 0.64 K/GPa. To the highest pressures, the linear slope of dR(ab)/dT within the ab plane decreases with increasing pressure, as does the residual resistance even as the critical temperature passes through a maximum at 95.2 K and 11.3 GPa. Comparison with the pressure data of Klotz, Reith, and Schilling [Physica C 172, 423 (1991)] for an apparently equivalent crystal requires that the singular importance of the carrier concentration in the planes as that factor which solely determines T(c) be readdressed.