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

We report measurements of the temperature and pressure dependence of the electrical resistivity (rho) of single-crystalline iron-based chalcogenide Cs0.8Fe2Se2. In this material, superconductivity with a transition temperature (T-c) similar to 30 K 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 T-c suppression around p(c) similar to 8 GPa. Even at 9 GPa a metallic resistivity state is not recovered, and the rho(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. (C) 2011 Elsevier Ltd. All rights reserved.