ab-plane optical properties of Fe-substituted ${\mathrm{Bi}}_2{\mathrm{Sr}}_2{\mathrm{CaCu}}_2{\mathrm{O}}_{8+\delta }$

The ab-plane reflectance of Fe-substituted ${\mathrm{Bi}}_2{\mathrm{Sr}}_2\mathrm{Ca}({\mathrm{Cu}}_{1-x}{\mathrm{Fe}}_x{)}_2{\mathrm{O}}_{8+\delta }$ single crystals grown by a floating method was measured above and below $T_c$ and optical conductivity was calculated using a Kramers-Kronig analysis. Detailed studies of the optical parameters of the sample with $x=0.015\mathrm{}$ at temperatures 10, 50, 70, 85, 110, 200, and 300 K reveal that the fraction of normal and condensed carriers decrease with increased Fe doping. Furthermore, they show that the decrease in condensed carrier density is a direct result of the reduction of the density of the normal carriers.