Studies on the Bi System Josephson Junctions with High Criteical Temperature

高临界温度Bi系约瑟夫森结的研究

基本信息

批准号：
07455138
负责人：
HAYAKAWA Hisao
金额：
$ 4.48万
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：
1995
资助国家：
日本
起止时间：
1995 至 1996
项目状态：
已结题

项目摘要

Among Bi_2Sr_2Ca_<n-1>Cu_nO_x superconductors, n=3 phase (2223 phase) is an oxide superconductor which has a critical temperature more than 100K.This material has the possibility to realize devices more stable and of better performance than those of Y system superconductor. In this research, on the basis of the thin film technology of 2223 phase, we tried to fabricate the following Josephson junctions.1. Edge-type Junctions :We fabricated edge type junctions using the 2223 phase as the superconducting electrodes and the 2201 phase as the middle layr. Their properties were RSJ-like. It was suggested that the grain boundary at the bottom of the step of the upper electrode also worked as a junction.2. Grain-boundary Junctions :(1) Bicrystal Junctions :We tried to fabricate grain-boundary Josephson junctions using 2223 phase films deposited on bicrystal substrates. Their properties are similar to those of Y system superconductor. On the other hand, the high junction resistances and the low … More critical current were confirmed as characteristic features of the grain-boundary junctions of the 2223 phase. By analyzing the junction characteristics, it was found that there are normal phase layrs near the insulating layr in the junction. The conduction mechanism of the junction was discussed. SQUID's were also fabricated using this bicrystal junction. The critical current was modulated periodicaly by the external magnetic field, and in spite of the small modulation, relative large output valtage was observed reflecting its high dynamic resistance, though we have not evaluated their noise properties.(2) Step-Edge Junctions :We fabricated step-edge type grain-boundary junctions by depositing the 2223 thin film on the MgO step substrate. The current-voltage characteristics was RSJ-like and it was suggested that the grain boundaries were formed at the top and the bottom of the step. Junctions using the films annealed for a short time revealed the improvement of the critical temperature, the critical current and the I_cR_n product of the junction. The possibility that there are normal phase layrs near the insulating layr in the junction was also suggested.3. Intrinsic Junctions :We tried to fabricate the intrinsic junctions using the 2223 phase thin films on the SrTiO_3 step substrates. The gap structure corresponding to the number of the layrs, i. e., the series Josephson junctions was observed. Less

在BI_2SR_2CA__ <N-1> CU_NO_X超导体中，n = 3相（2223阶段）是一种氧化物超导体，其临界温度超过100K。该材料有可能实现比Y系统超级导管的设备更稳定和更好的性能。在这项研究中，根据2223阶段的薄膜技术，我们试图制造以下约瑟夫森连接。1。边缘型连接：我们使用2223阶段作为超导电子和2201相作为中间路线制造了边缘类型连接。它们的特性类似于RSJ。有人提出，上电极台阶底部的晶界也可以用作交界处。2。晶界交界处：（1）双晶连接：我们尝试使用沉积在Bichrystal基板上的2223个相膜来制造晶界的约瑟夫森连接。它们的性质类似于Y系统超导体的特性。另一方面，高连接电阻和低……更关键的电流被确认为2223阶段晶界连接的特征。通过分析连接特性，发现连接处的隔热Layr附近有正常相位。讨论了结的传导机制。鱿鱼还使用该双交界处制造。临界电流是通过外部磁场调节的，尽管我们尚未评估它们的噪声特性，但仍观察到相对大的输出阀反映了其高动态电阻。（2）踏板连接：我们通过在MGO MGO上的2223薄膜上沉积了2223个薄膜。电流 - 电压特性类似于RSJ，并建议晶界在台阶的顶部和底部形成。使用膜短时间退火的连接揭示了连接点的临界温度，临界电流和I_CR_N产品的改善。还提出了连接处的绝缘层附近有正常相位的可能性。3。固有连接：我们尝试使用SRTIO_3步骤底物上的2223相薄膜来制造固有的连接。观察到与Layrs数量相对应的间隙结构，即观察到Josephson连接系列。较少的