12kBTcoptical signature of superconductivity in single-domainBi2Sr2CaCu2O8

Abstract

Infrared and far-infrared transmittance measurements were performed on ${\mathrm{Bi}}_2$ ${\mathrm{Sr}}_2$ ${\mathrm{CaCu}}_2$ ${\mathrm{O}}_8$ (2:2:1:2) and ${\mathrm{Bi}}_2$ ${\mathrm{Sr}}_2$ ${\mathrm{CuO}}_6$ (2:2:0:1). Below ${\mathit{T}}_{\mathit{c}}$, a characteristic feature occurs at ω=700 ${\mathrm{cm}}^{\mathrm{-}1}$ (12${\mathit{k}}_{\mathit{B}}$ ${\mathit{T}}_{\mathit{c}}$) in the 2:2:1:2 material. No similar feature is found in the 2:2:0:1 compound. The 2:2:1:2 material also showed substantial ab-plane anisotropy.