Preparation of Bi2Sr2CaCu2O8+δ/CeO2/Bi2Sr2CaCu2O8+δ trilayer thin films by the sol-gel method

In this paper, trilayer thin films of Bi 2 Sr 2 CaCu 2 O 8+δ /CeO 2 /Bi 2 Sr 2 CaCu 2 O 8+δ (Bi-2212/CeO 2 /Bi-2212) were fabricated using a dip-coating method, with the heat treatment temperature decreased layer by layer. The growth characteristics and superconducting properties of these trilayer thin films were investigated. Results indicate that the c -axis epitaxial growth characteristics of the bottom Bi-2212 film are maintained. Epitaxial growth relationship at the Bi-2212/CeO 2 /Bi-2212 interfaces were further confirmed by STEM imaging. The critical transition temperatures ( T c ) of the top and bottom Bi-2212 films is 72 K and 74 K, respectively. Critical current ( I c ) values decrease with increasing CeO 2 film thickness. At a CeO 2 film thickness of 116 nm, the resistivity between the two Bi-2212 films is 8.6 × 10 11 Ω·cm. This high resistivity demonstrates that a thicker intermediate CeO 2 layer can function effectively as an insulator for superconducting magnetic flux converter applications.