Phase diagram of pressure-induced superconductivity in EuFe_{2}As_{2} probed by high-pressure resistivity up to 3.2 GPa (original) (raw)
We have constructed a pressure−temperature (P −T) phase diagram of P-induced superconductivity in EuFe2As2 single crystals, via resistivity (ρ) measurements up to 3.2 GPa. As hydrostatic pressure is applied, an antiferromagnetic (AF) transition attributed to the FeAs layers at T0 shifts to lower temperatures, and the corresponding resistive anomaly becomes undetectable for P ≥ 2.5 GPa. This suggests that the critical pressure Pc where T0 becomes zero is about 2.5 GPa. We have found that the AF order of the Eu 2+ moments survives up to 3.2 GPa without significant changes in the AF ordering temperature TN. The superconducting (SC) ground state with a sharp transition to zero resistivity at Tc ∼ 30 K, indicative of bulk superconductivity, emerges in a pressure range from Pc ∼ 2.5 GPa to ∼ 3.0 GPa. At pressures close to but outside the SC phase, the ρ(T) curve shows a partial SC transition (i.e., zero resistivity is not attained) followed by a reentrant-like hump at approximately TN with decreasing temperature. When nonhydrostatic pressure with a uniaxiallike strain component is applied using a solid pressure medium, the partial superconductivity is continuously observed in a wide pressure range from 1.1 GPa to 3.2 GPa.
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