Enhanced Superconductivity in FeTe0.8S0.2 via Sn Doping

Polycrystalline samples of Sn/FeTe0.8S0.2 with weight ratio x (Sn: FeTe0.8S0.2) = 0%, 3%, 5%, and 7% were successfully synthesized. Morphological characterizations of the samples indicate that introducing Sn is beneficial for grain growth, thus contributing to enhancement of superconductivity. In particular, the x = 3% sample exhibits a sharp superconducting transition and \( T_{\text{c}}^{\text{zero}} \) is increased by about 3 K based on R–T curves. The low-melting-point material, Sn, is proposed to have two roles. One role is acting as the adhesive to combine the adjacent particles at the melting temperature of Sn, which is of benefit for improving the \( T_{\text{c}}^{\text{zero}} \) of the superconductivity. The other role is acting as the dopant in the tetragonal phase, which is of benefit for improving the \( T_{\text{c}}^{\text{onset}} \) of the superconductivity. This proposal may provide a new strategy for improving the superconductivity in other superconductors.