Effects of Pressure and Magnetic Field on the Pressure-Induced Superconductivity in EuFe2As2

We have performed electrical resistivity measurements of EuFe2As2 under hydrostatic pressures (P) up to 3.2 GPa and magnetic fields up to 15 T. In zero field, the superconducting (SC) ground state with a sharp transition to zero resistivity, indicative of bulk superconductivity, emerges at Tc ~ 30 K in a pressure range from 2.5 GPa to ~ 3.0 GPa. Under applied field of 15 T, the SC transition is suppressed to lower temperatures with increasing pressure, suggesting that the application of pressure reduces the upper critical field Bc2 for the P-induced superconductivity. Meanwhile, the antiferromagnetic (AF) order of the Eu2+ moments survives up to 3.2 GPa, the highest pressure in the experiments, with no significant change in the AF ordering temperature and the magnetic field effect.