Optical Spectra of (Bi, Pb)2(Sr, Ca)4Cu3O10 Superconductors

Abstract
Visible-to-near-infrared optical spectra of (Bi, Pb)2(Sr, Ca) n+1Cu n O y superconductors (n=2, 3) have been measured by both reflection and transmission modes. The spectra of the n=2 and n=3 phase are quite different from each other. From the estimated plasma frequency ωp, the relation T c∝ωp 2 reported previously on La-Sr-Cu-O and Y-Ba-Cu-O seems to be valid in (Bi, Pb)2(Sr, Ca)4Cu3O10. The origin of the optical transition appearing in the infrared region is discussed.