Influence of the Fluoride Atoms Doping on the FeSe Superconductor

Abstract

It is reported the influence of the interstitial atoms doping on the FeSe superconductor. Polycrystalline samples with FeSeFx and FeSeBx nominal compositions were prepared by solid state reaction. An enhancement of the superconducting transition temperature was observed in the temperature dependence of the electrical resistivity curve to the FeSeF0.015 sample. R(T) data display superconducting behavior close to 12 K. The Tc increased with F doping by up to 50%. In contrast, boron doping no change the superconducting properties of the FeSe compound. As the FeSeFx and FeSeBx system the fluoride doping introduce a negative chemical pressure in the FeSe superconductor. This fact suggests that fluoride doping have changed the electronic properties of the FeSe phase.