We have constructed a pressureβtemperature (PβT) phase diagram of
P-induced superconductivity in EuFe2βAs2β single crystals, via
resistivity (Ο) measurements up to 3.2 GPa. As hydrostatic pressure is
applied, an antiferromagnetic (AF) transition attributed to the FeAs layers at
T0β shifts to lower temperatures, and the corresponding resistive
anomaly becomes undetectable for Pβ₯ 2.5 GPa. This suggests that the
critical pressure Pcβ where T0β becomes zero is about 2.5
GPa. We have found that the AF order of the Eu2+ moments survives up to
3.2 GPa without significant changes in the AF ordering temperature
TNβ. The superconducting (SC) ground state with a sharp transition
to zero resistivity at TcββΌ 30 K, indicative of bulk
superconductivity, emerges in a pressure range from PcββΌ 2.5
GPa to βΌ 3.0 GPa. At pressures close to but outside the SC phase, the
Ο(T) curve shows a partial SC transition (i.e., zero resistivity is not
attained) followed by a reentrant-like hump at approximately TNβ
with decreasing temperature. When nonhydrostatic pressure with a uniaxial-like
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.Comment: 7 pages, 6 figures, accepted for publication in Physical Review B,
selected as "Editors' Suggestion