Figure 5. The dome-shaped superconducting Tc–P phase diagram and possible interpretation.
(a) Onset temperature of the superconductivity plotted against applied pressure. A maximum Tc of 7 K occurs near 20 GPa. In runs no. 1 and 2, no pressure-transmitting medium was used while for run no. 3, Daphne oil was used as the pressure medium. The right-hand axis is the magnetoresistance ratio, which is strongly suppressed by the pressure. (b) The calculated density of states at the Fermi level plotted against pressure.