Effect of S-doping on the magnetic and electrical properties of FeSe superconductor.

• Superconducting properties of polycrystalline FeSe 1 − x S x S x (x = 0.1 and 0.2) alloys are investigated. • Impact of external hydrostatic pressure and chemical pressure on the superconducting state. • Anomalous behavior of superconducting transition temperature. • Non-Fermi liquid type behavior of normal state resistivity. • Signature of flux flow resistance in the isothermal resistivity data as a function of external magnetic field. Here we report on the magnetic and magneto-transport behavior of Fe-based superconductor with nominal compositions FeSe 1 − x S x (x = 0.1 and 0.2). The impact of external hydrostatic pressure (P) and chemical pressure on the superconducting state of the FeSe system has been investigated in this work. Superconducting transition temperature (T c) is found to be shifted towards higher temperatures with 10% S doping at the Se site of the FeSe alloy. On further increase in the doping concentration (for x = 0.2), the superconducting T c decreases. We have also observed a significant effect of external P on the superconducting properties of these S-doped alloys. Different superconducting parameters calculated from our experimental data confirm the type-II superconducting nature of the studied compounds. The signature of flux flow resistance is observed in the isothermal resistivity data as a function of the external magnetic field. [ABSTRACT FROM AUTHOR]