A Study on Transport Mechanism in High-Temperature Superconductor Josephson Junctions and Their Application to 60K-Electronics

高温超导约瑟夫森结输运机制及其在60K电子学中的应用研究

• 批准号: 09450142
• 负责人: FUJIMAKI Akira
• 金额: $ 1.98万
• 依托单位: Nagoya University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 1997
• 资助国家: 日本
• 起止时间: 1997 至 1998
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09450142/
• 关键词: High-temperature superconductor; Josephson Junctions; localized states; 金属-絶縁体転移

The purpose of this work is to understand the transport mechanisms in Josephson junctions based on high-temperature superconductors, leading to 'usable' Josephson junctions operating at 60 K.We study electrical properties of Yba_2Cu_3O_7 ramp-edge Josephson junctions with PrBa_2Cu_30_7-based barriers having different resistivities. Experimental results show that the transport mechanism of the pair particles is direct tunneling, whereas that of quasipartioles is resonant tunneling in addition to the direct tunneling. We also find that the high density of the localized states in the barriers reduces the quality parameter, IcRn products, where Ic and Rn are a critical current and a junction resistance, respectively. In fact, high IoRn values are obtained up to 6mV in the junctions with highly resistive Ga-doped PBCO barriers.We face the several drawbacks to the development of the usable junctions. The most serious one is the large spread of the junction parameters such as Ic, Rn. We find that the deposition of the barriers or counter-electrodes increase the spread. To break this situation, we have developed the Josephson junctions without artificial barriers and succeeded in the reduction of the spread.

本工作的目的是了解基于高温超导体的Josephson结中的输运机制，从而使Josephson结在60 K下工作。我们研究了YBa_2Cu_3O_7斜坡边Josephson结与不同介电常数的PrBa_2Cu_3O_7基势垒的电学性质。实验结果表明，对粒子的输运机制是直接隧穿，而准粒子的输运机制除了直接隧穿外，还包括共振隧穿。我们还发现，高密度的局域态的障碍降低了质量参数，IcRn产品，其中Ic和Rn是一个临界电流和结电阻，分别。事实上，在具有高阻性Ga掺杂PBCO势垒的结中获得了高达6mV的高IoRn值。其中最严重的是结参数如Ic、Rn的大范围扩散。我们发现，沉积的障碍或反电极增加的蔓延。为了打破这种局面，我们已经开发出约瑟夫森结没有人工障碍，并成功地减少了蔓延。

项目成果

M.Horibe,K.Kawai,A.Fujimaki,H.Hayakawa: "Ramp-edge Josephson junctions using barriers of various resistivities" IEICE Trans.Electronics. Vol.E81-C,No.10. 1526-1531 (1998)

M.Horibe、K.Kawai、A.Fujimaki、H.Hayakawa：“使用各种电阻率势垒的斜坡边缘约瑟夫森结”IEICE Trans.Electronics。