Evidence for a reentrant superconducting state inEuFe2As2under pressure

Abstract

We studied the temperature-pressure phase diagram of ${\text{EuFe}}_{2}{\text{As}}_{2}$ by electrical resistivity measurements. The spin-density-wave transition at ${T}_{0}$ associated with the FeAs-layers is continuously suppressed with increasing pressure, while the antiferromagnetic ordering temperature of the ${\text{Eu}}^{2+}$ moments seems to be nearly pressure independent up to 2.6 GPa. Above 2 GPa a sharp drop of the resistivity, $\ensuremath{\rho}(T)$, indicates the onset of superconductivity at ${T}_{c}\ensuremath{\approx}29.5\text{ }\text{K}$. Surprisingly, on further reducing the temperature, $\ensuremath{\rho}(T)$ is increasing again and exhibiting a maximum caused by the ordering of the ${\text{Eu}}^{2+}$ moments, a behavior which is reminiscent of reentrant superconductivity as it is observed in the ternary Chevrel phases or in the rare-earth nickel borocarbides.