Pressure dependence of the superconducting transition temperature in single crystals of ${\mathrm{Tl}}_2$${\mathrm{Ba}}_2$${\mathrm{Ca}}_2$${\mathrm{Cu}}_3$${\mathrm{O}}_{10\mathrm{-}\mathit{x}}$

The pressure dependence of the superconducting transition temperature, ${\mathit{T}}_{\mathit{c}}$(P), has been measured in single crystals of ${\mathrm{Tl}}_2$${\mathrm{Ba}}_2$${\mathrm{Ca}}_2$${\mathrm{Cu}}_3$${\mathrm{O}}_{10\mathrm{-}\mathit{x}}$. In two overdoped samples, ${\mathit{T}}_{\mathit{c}}$(P) is observed to increase from 116 K at atmospheric pressure to 131.8±0.5 K at 7 GPa. We believe this is the highest ${\mathit{T}}_{\mathit{c}}$ reported to date. The initial slope, ${\mathit{dT}}_{\mathit{c}}$/dP, was measured to be 4.8±0.3 K/GPa. For samples with ${\mathit{T}}_{\mathit{c}}$’s at atmospheric pressure approaching the reported optimum value for this compound of 125 K, the effect of pressure is reduced. These results are discussed in terms of existing theoretical models.