New modulated structure in a Pb-doped Bi-Ca-Sr-Cu-O superconductor

Abstract

A new modulated structure has been observed in a Pb-doped Bi-Ca-Sr-Cu-O superconductor (Tc,0=105 K) in addition to the incommensurate modulated structure reported by several researchers. This new modulation occurs in the b* direction and shows up as satellite spots to each of the original diffracted spots. Upon cooling to 88 K the diffraction spots due to the original modulation disappear, while the spots due to the new modulation remain. In the case of the undoped samples, the modulation does not disappear upon cooling to 30 K, which is below the Tc,0 of the sample (∼75 K).