Cross-Sectional High-Resolution Transmission Electron Microscope Studies of Superconducting Oxide Thin Films of the Bi-System

抄録

Structures of artificial Bi–O/Sr–Ca–Cu–O multilayered films with a designed period of c=3.7 nm have been examined by a cross-sectional TEM method. The modulated structure similar to bulk BSCCO can be seen in both samples cooled in oxygen, which are superconductors of T_c(zero)=10–30 K, and samples cooled in vacuum, which are not superconductors. In the films, Bi atoms frequently shift from the standard position of bulk BSCCO. In the most of the grains a and b axes of the films are parallel to ⟨100⟩ of the MgO substrate. The epitaxial growth is discussed considering that both Bi–O layers and MgO have the rock salt type structure.