Study of Strong Superconducting Coupling between High Tc and Low Tc Superconducting layers by Interface-Control

高温与低温超导层间强超导耦合的界面控制研究

• 批准号: 13650016
• 负责人: TERADA Norio
• 金额: $ 2.37万
• 依托单位: Kagoshima University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2001
• 资助国家: 日本
• 起止时间: 2001 至 2003
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-13650016/
• 关键词: High Tc Superconductors; Surface-Interface Control; Superconducting Order Parameter; Active Oxygen beam; Photoemission Spectroscopy; Proximity Effect; 金属系超伝導体; 超伝導オーダーパラメーター; 電子状態接続

An enhancement of superconducting coupling between high temperature superconducting (HTS) layer and low temperature one, which is seriously suppressed in usual interfaces by structural defects and interface-reactions, has been attempted by controlling electronic structure of the HTIS-side region. In the present project, YBa_2Cu_3O_<7-δ> (YBCO) films was selected as the HTS layer. In the first stage, for developing an intrinsic surface nature with the original amplitude of the order parameter, we have adopted a cleaning of the YBCO surface by an annealing under an intensive atomic oxygen beam. This treatment yielded an elimination of carbon-related impurities and a development of metallic feature in in-situ ultraviolet photoemission spectra. The height of the Fermi edge of the treated a-, and c-YBCO films was as high as 10 % of Cu 3d characterized peak in their valence band, which was comparable with that of vacuum-cleaved single crystals at a cryogenic temperature. The optimum treatmen … More t condition in the present study was as follows : an annealing temperature of 450 ℃ and a flux density of the atomic oxygen above 5x10^<15> atoms/cm^2・sec. Because of the high electron density of states, a contact resistibity between the optimally treated c-YBCO surface and in-situ deposited Au reached in the range of 1〜5x10^<-9> Ω・cm^2. A high critical current density up to 7x10^5 a/cm^2 at 4.2 K was also achieved in the Pb-In/Ag ; 1〜2 nm /Au ; 1〜2 nm /c-YBCO (optimally treated) multiplayer structure. A suppression of tunneling conductance around zero bias was observed in scanning tunneling spectroscopy on the (ultra thin Au)/c-YBCO surface at 4.2 K, which could be explained by propagation of superconducting proximity effect through the Au layer. The obtained transport properties meet requirements in design of integrated circuits. And the results also indicate an usefulness of the control of the surface of HTS layers by using both the atomic oxygen treatment and in-situ characterization of the electronic structure. Less

高温超导层与低温超导层之间的超导耦合在通常的界面处受到结构缺陷和界面反应的严重抑制，本文试图通过控制高温超导层侧区域的电子结构来增强高温超导层与低温超导层之间的超导耦合。本课题选用YBa_2Cu_3O_（7-δ）（YBCO）薄膜作为高温超导层。在第一阶段，为了发展具有序参数原始幅度的本征表面性质，我们采用了在强原子氧束下退火来清洁YBCO表面。这种处理产生了消除碳相关的杂质和发展的金属功能在原位紫外光电子能谱。处理后的a-，和c-YBCO薄膜的费米边缘的高度是高达10%的Cu 3d特征峰在其价带，这是可比的真空解理单晶在低温下。最佳治疗方法 ...更多信息 实验条件为：退火温度为450 ℃，原子氧通量密度大于5 × 10 ~ 4 <15>atoms/cm ~ 2·sec。由于高的电子态密度，最佳处理的c-YBCO表面与原位沉积的Au之间的接触电阻率达到1 × 10 ^<-9>Ω·cm ^2。在Pb-In/Ag、1 × 10^2 nm /Au、1 × 10^2 nm /c-YBCO（优化处理）多层结构中，在4.2 K下也获得了高达7 × 10^5 a/cm^2的高临界电流密度。在4.2 K时，扫描隧道谱中观察到（超薄Au）/c-YBCO表面在零偏压附近的隧穿电导被抑制，这可以用超导邻近效应在Au层中的传播来解释。所获得的输运特性满足集成电路设计的要求。原子氧处理和电子结构原位表征相结合的方法对控制高温超导层的表面是有效的。少

项目成果

N.Terada, Kotaro Ohki, A.Ohtomi, S.Miyanomae, K.Obara, H.Akoh, H.Sato, T.Yamada, E.Fujimoto: "In-situ characterization of Engineered Surfaces of c-YBCO Films for Sandwich type Junction"IEEE Trans Appl.Supercond.. Vol.13. 813-816 (2003)

N.Terada、Kotaro Ohki、A.Ohtomi、S.Miyanomae、K.Obara、H.Akoh、H.Sato、T.Yamada、E.Fujimoto：“三明治用 c-YBCO 薄膜工程表面的原位表征

K.Eguchi, S.Y.Park, N.Terada, K.Obara: "Cooperative phenomena in super-thin oxide layer on metallic electrode"Trans.of Mat.Res.Soc.Japan. Vol.26 No.4. 1295-1298 (2001)

K.Eguchi、S.Y.Park、N.Terada、K.Obara：“金属电极上超薄氧化层的合作现象”Trans.of Mat.Res.Soc.Japan。

K.Ohki: "In-situ Characterization of Thermal Stability and Depth Profile of Electronic Structure of Engineered Surfaces of c-axis YBa_2Cu_3O_<7-δ> films"Proc.EUCAS2003. (in press). (2004)

K.Ohki：“c 轴 YBa_2Cu_3O_<7-δ> 薄膜的工程表面的热稳定性和深度剖面的原位表征”Proc.EUCAS2003（印刷中）。

K.Ohki: "In-situ Characterization of Electronic Structure of Engineered Surfaces of c-axis YBCO films for Sandwich type Junctions"J.Met.Res.Soc.Jpn. (in press). (2004)

K.Ohki：“用于三明治型结的 c 轴 YBCO 薄膜工程表面电子结构的原位表征”J.Met.Res.Soc.Jpn。

N.Terada, K Ohki, A OHTOMI, S.Miyanomae, K.Obara, H.Akoh, H.Sato, H.Yamada, E.Fujimoto: "In-situ Characterization of Engineered Surfaces of c-axis YBCO Films for Sandwich type of Junctions"IEEE Trans. Appl. Superconductivity. vol.13(in press). (2003)

N.Terada、K Ohki、A OHTOMI、S.Miyanomae、K.Obara、H.Akoh、H.Sato、H.Yamada、E.Fujimoto：“三明治用 c 轴 YBCO 薄膜工程表面的原位表征