Experimental evidence for bulk superconductive behavior of EuMo6S8under pressure

The pressure dependences of the structural and superconducting transition temperatures ($T_s$ and $T_c$, respectively) of a melted high-quality sample of Eu${\mathrm{Mo}}_6$ ${\mathrm{S}}_8$ have been measured under nearly hydrostatic pressure up to ∼15 kbar. Applied pressure ($P$) depresses $T_s$ rapidly from $T_s$ 109 K at zero pressure to $T_s=0\mathrm{}$ just below 13 kbar where the slope $\frac{d{T}_s}{\mathrm{dP}}$ is nearly vertical. A very sharp superconducting transition is observed above 13 kbar; at 13.2 kbar, $T_c=12.2\mathrm{}$ K and has a width $\Delta T_c=0.03\mathrm{}$ K. Above 13 kbar, $T_c$ decreases nearly linearly with pressure at a rate $\frac{d{T}_c}{\mathrm{dP}}=-0.18\mathrm{}$ K/kbar, which is comparable to that observed for other superconducting Chevrel-phase compounds. The upper critical magnetic field $H_{c2}$ as a function of temperature was measured up to 8 T and displays features that are indicative of the exchange-field compensation effect.