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

Here we report on the magnetic and magneto-transport behavior of Fe-based superconductor with nominal compositions FeSe1_xSx (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 Tc 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 super-conducting 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.