Our recent systematic examination of the pressure effect on high-temperature superconductors revealed that the highest achievable superconducting transition temperature (Tc) in the layered cuprates may lie between ∼150 and ∼180 K. We propose that the newly discovered Hg-Ba-Ca-Cu-O (HBCCO) compound system may be one of the most promising candidates for such a high-Tc superconductor, because of the possible large range of modulation doping associated with the linear oxygen coordination of divalent Hg in HBCCO. A record-high magnetically determined transition at 135 K with a zero resistivity at 134 K has been obtained by us in HgBa2Ca2Cu3O8+δ. The Tc of HgBa2Ca2Cu3O8+δ was found to increase continuously with pressure at an increasing rate up to ∼17 kbar without any sign of saturation. The thermo-power shows an underdoped characteristic. These observations suggest that the Tc of HBCCO can be further enhanced with proper modulation doping without inducing any structural instabilities. The results together with the synthesis steps of HBCCO are summarized and discussed.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Physics and Astronomy (miscellaneous)