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Pressure cycle of superconducting Cs0.8Fe2Se2: a transport study

We report measurements of the temperature and pressure dependence of the electrical resistivity of single crystalline iron-based chalcogenide Cs0.8Fe2Se2. In this material superconductivity Tc~30K develops from a normal state with extremely large resistivity. At ambient pressure a large "hump" in the resistivity is observed around 200K. Under pressure, the resistivity decreases by two orders of magnitude, concomitant with a sudden Tc suppression around p~8GPa. Even at 9GPa a metallic resistivity state is not recovered, and the ρ(T) "hump" is still detected. A comparison of the data measured upon increasing and decreasing the external pressure leads us to suggest that superconductivity is not related to this hump.