Preparation of (11n) oriented Bi2Sr2CaCu2O8+x thin films without c-axis twin structure by the metal-organic decomposition method using vicinal SrTiO3 (110) substrates

摘要

We have prepared (11n) oriented Bi₂Sr₂CaCu₂O_8+x (Bi2212) thin films by metal-organic decomposition method. The vicinal (110) substrate of SrTiO₃ (STO) inclined toward the [1ˉ10] direction was used for suppressing “c-twinning”. In the sample prepared in the O₂ atmosphere, only the (11n) peak appeared in the θ-2θ X-ray diffraction pattern. When the miscut angle of the substrate was φ = 10°, it was shown by the scanning electron microscope images and the (008) pole figures that the c-axis was inclined by about 38° and the c-twinning was substantially suppressed. ρ_ab and ρ_c of this sample were calculated by the corrected van der Pauw method and component calculation of the two-dimensional resistivity tensor. The superconducting transition temperatures were T_c = 81 K. The temperature dependence of ρ_ab was a typical metallic behavior reflecting the characteristics of the ab-plane of Bi2212. On the other hand, that of ρ_c did not become a typical semiconductor behavior in the c-axis direction of Bi2212, but it showed a metallic behavior. The anisotropic parameter γ was about 10.