Effect of pressure on the superconducting transition temperature of doped and neutron-damaged MgB2

Abstract Measurements of the superconducting transition temperatures for Al-doped, C-doped and neutron-damaged–annealed MgB 2 samples under pressure up to ∼8 kbar are presented. The d T c /d P values change systematically with the decrease of the ambient pressure T c in a regular fashion. The evolution of the pressure derivatives can be understood assuming that the change in phonon spectrum is a dominant contribution to d T c /d P .