Superconductivity up to 147 k in hgba₂CaCu₂O_6+ᵟunder quasi-hydrostatic pressure

The superconducting transition temperature of the n = 2 member of the homologous series HgBa₂Ca_n-1Cu_nO_2n+2+ᵟ+ 2 + i with two CuO₂layers per unit cell has been measured under quasi-hydrostatic pressures up to about 18-5 GPa. Superconductivity up to 147 K has been detected with a main transition at 138K at 18-5 GPa without saturation. This represents the highest superconducting transition temperature ever reported in a cuprate compound with two CuO₂layers. It is expected that superconductivity at temperatures higher than 147 K. can be achieved in this compound either under higher pressures or by chemical substitution at ambient pressure.