Dependence of the superconducting transition temperature of HgBa2CuO4+δ on hydrostatic pressure

✍ Scribed by A.-K. Klehe; A.K. Gangopadhyay; J. Diederichs; J.S. Schilling

• Publisher: Elsevier Science
• Year: 1993
• Tongue: English
• Weight: 386 KB
• Volume: 213
• Category: Article
• ISSN: 0921-4534
• DOI: 10.1016/0921-4534(93)90441-r

✦ Synopsis

The real X' and imaginary Z" components of the AC susceptibility for a ceramic sample of superconducting HgBa2CuO4+6 have been measured at HAC = 0.1 Oe over the temperature range 80-300 K under purely hydrostatic pressure conditions. Upon cooling, a slight but sharp decrease in slope dz'/dT occurs at the "upper" transition temperature, T~ = 98 K, which we attribute to the onset of superconductivity in a small volume ( ~ 3%) of the sample which is nearly optimally doped. Below the "lower" transition temperature, T~¢ -~ 95 K, Z' (T) drops steeply, approaching for T< 90 K a value which corresponds to ~ 80% of ideal shielding. The imaginary or loss component Z" (T) shows an onset at 95.5 K followed by a maximum at 93.3 K. Under an applied He-gas pressure to 0.9 GPa, both T~ and T~¢ increase reversibly at the moderate rate dT¢/dP ~ -+ 1.75 + 0.1 K/GPa which is independent of whether the pressure is changed at room temperature or 80 K. These experiments allow us to speculate that the superconducting transition for optimally doped HgBa2CuO4+6 at ambient pressure probably lies near 98 K.