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

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

► The resistivity of the Fe-based superconductor CsFe2Se2 has been measured under high pressure.
► The transition temperature is suppressed from 30 K (p=0p=0) to zero at around 7.5 GPa.
► The resistivity hump at 200 K seems unrelated to the superconductivity.