Research on High Tc superconducting three terminal devices utilizing the function of grain boundary

利用晶界作用的高温超导三端器件研究

• 批准号: 06650349
• 负责人: NAKAJIMA Kensuke
• 金额: $ 1.47万
• 依托单位: Tohoku University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (C)
• 财政年份: 1994
• 资助国家: 日本
• 起止时间: 1994 至 1995
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-06650349/
• 关键词: High Tc Superconductivity; Three terminal device; Josephson junction; Grain boundary; 電界効果; 人工粒界; YBCO; High Tc Superconductivity; Three terminal device; Josephson junction; Grain boundary; 電界効果; 人工粒界; YBCO

Field effects of High-T_c Oxide Superconductors expected from their characterisctics of low carrier densities and short coherent lengths are hopefully applicable to superconducting three terminal devices. To achieve actual devices, however, a lot of difficulties, i. e fabrication of high quality ultra thin ETSC films with the thickness of several nm and development of insulating layr with a large dielectric constant still remains. From the another point of view, tilt grain boundaries not only behave as Josephson junctions but also have a large field sensitiviy because of local deficiency of charge carriers due to oxygen deficiency in the boundaries.In this research, we have investigated the electric field effects on artificial grain boundaries of YBCO films and obtained following results.・The carrier density of the grain boundary was evaluated to be 2-5*10^<20>cm^<-3> from the measurement of the electric field effect on a normal conducting artificial grain boundary adjoining two superc … More onducting YBCO grains. The carrier density was one drder lower than that in inner grains so that large electric field effects were expected. This is the first result indicating the usefulness of grain boudaries as field effect channels.・As electric field effects with respect to AC and DC Josephson effects on the grain boundaries behaving as Josephson junctions, electric field modulations of both critical current, I_c and self resonance frequency were observed. For former effect, it was shown that the field effect in I_c was qualititavely explained by a charge carrier modulation in grain boundary junctions on the basis of the SNS model. For later one, the variations of the resonance frequencies were attributed to changes in the effective dielectric constants, epsilon^GB_/d reflecting the field strength dependence ofthe dielectric constant of STO used as substrates. The electric field modulation of epsilon^GB_/d is possibly applicable to the phase velocity control of electromagnetic waves transmitting in the grain boundaries in the case of Flux Flow Oscilator (FFO). Less

高-T_C氧化物超导体的现场效应从低载体密度和短相干长度的特征中预期，有望适用于超导三个末端设备。但是，要实现实际设备，很多困难，i。 E制造高质量的超薄ETSC膜，其厚度为几个NM，并且仍保留大量饮食常数的绝缘Layr。从另一个角度来看，倾斜的晶界不仅表现为约瑟夫森连接处，而且由于界限的局部电荷缺乏而具有较大的田间敏感性。在这项研究中，我们已经研究了电场对YBCO膜的人工晶界的电场影响，并在ybco膜的人工晶所界面上进行了影响。 2-5*10^<20> cm^<-3>从测量电场效应对正常导电的人造晶界的测量，毗邻两个Superc…更多偏移的YBCO晶粒。载体密度比内晶粒低一个DRDER，因此预期的电场效应很大。这是表明晶粒凸轮作为现场效应通道的有用性的第一个结果。・是在AC和DC Josephson对晶界的影响时的电场效应，观察到临界电流，I_C和自我共振频率的电场调制的晶界效应。对于以前的效果，证明I_C中的现场效应是通过社交网络模型基于晶界连接中的电荷载体调制来解释的。稍后，共振频率的变化归因于有效的饮食常数的变化，epsilon^gb_/d反映了用作底物的Sto饮食常数的场强依赖性。 EPSILON^GB_/D的电场调制可能适用于在通量流动振荡器（FFO）的情况下，电磁波传输的电磁波的相速度控制。较少的