Terahertz conductivity measurement of FeSe0.5Te0.5 and Co-doped BaFe2As2 thin films

Abstract

The terahertz (THz) conductivity of FeSe0.5Te0.5 (‘11’-type) and Co-doped BaFe2As2 (‘122’-type) thin films are investigated. For ‘11’-type, the frequency dependence of the complex conductivity can be understood as that of BCS-type superconductor near the superconducting gap energy, and we estimated the superconducting gap energy to be 0.6meV. For ‘122’-type, we estimated the superconducting gap energy to be 2.8meV, which is considered to be the superconducting gap opened at the electron-type Fermi surface near the M point.