講演情報
[20a-P03-19]I–V characteristics of the bilayer high-temperature superconducting heterostructures
〇Jiqiang Jia1,2, Minghu Shen1, Gaoyang Zhao1, Li Lei1, Yu Han1, Oshima Yoshifumi2 (1.XUT, 2.Jaist)
キーワード：
high-temperature superconducting heterostructure、self-sensitive chemical modification photolithography、Josephson junction
The Josephson junction (JJS) formed by inserting an ultra-thin non-superconductor between two superconductors can show high sensitivity to electrical and magnetic signals, making it have important applications in weak magnetic field detection, quantum computation, and THz wave transmission and reception. Although high-temperature superconductors (HTSs) have a higher working temperature than low-temperature superconductors (LTSs), their smaller coherence length makes it extremely difficult to prepare the non-superconducting interlayer (less than 2 nm). Therefore, most of the existing JJSs are prepared by using LTSs, and there is almost no report on the application of JJSs prepared by HTSs. In this study, the heterostructure was fabricated using two HTSs with different lattice constants, because their interface was expected to work as non-superconducting layer due to lattice mismatch. A self-developed novel micro-fabrication method, i.e., self-sensitive chemical modification photolithography, was used to prepare the fine-patterns of superconductor heterostructures. The cross-shaped Bi2Sr2CaCu2O8+σ/YBa2Cu3O7-x (BSCCO/YBCO) and GdBa2Cu3O7-y/YBa2Cu3O7-x (GBCO/YBCO) heterostructures were prepared (Figs.1(a1) and 1(a2)). The I-V curves (Figs.1(b) and 1(c)) and transmission electron microscope images (Figs.1(d1) and 1(d2)) were obtained to identify the electronic property and structure at the interfaces. We found that both heterostructures exhibit high epitaxial structure (less defects) and the zero-voltage supercurrent phenomenon which could be explained by superconductor/normal metal/superconductor-type Direct Current Josephson effect (DC-JE) since the slopes of Log(Is) - Log(1-T/Tc) relationship were about 2. It was considered that an intermediate transition layer (~1.3 or 1.2 nm) were formed at the BSCCO/YBCO and GBCO/YBCO interfaces, which may lead to DC-JE.These results show that JJSs could be prepared by bilayer superconducting heterostructures.