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

高T_c氧化物超导体期望从其低载波密度和短相干长度的特征学中产生的场效应可能很好地适用于超导体三个终端设备。要实现实际的设备， However，有很多不同的东西， I。e制造高质量超薄的ETSC薄膜与几个nm的厚度和开发的绝缘层与一个大的dielectric constant仍然保留。从另一个角度来看，倾斜的谷物边界不仅仅是表面作为Josephson交叉点，但也有一个较大的磁场敏感性，因为电荷载体的局部缺陷而导致了边界中的氧缺陷。在这项研究中，我们调查了YBCO薄膜人工谷物边界的电磁场影响，并获得了以下结果。谷物边界的载体密度已被评估为2-5*10^<20>cm^&lt;-3&gt;从正常情况下对人造谷物边界的电场效应的测量结果两个超级计算机 ... More 使用YBCO Grains。运载火箭密度是一个低于内部颗粒的博士，因此较大的电磁场效应是预期的。这是第一个结果，将谷物边界作为磁场效应通道的可用性指示出来。作为对AC和DC Josephson对谷物边界行为的影响的响应，作为Josephson跳线、两个关键电流的电场调制、I_c和自身共振频率观察到。对于前效应，它显示了I_c中的场效应，它被准确地解释了SNS模型基础上的电荷载体调制中的颗粒边界连接。对于后来的一个，共振频率的变化被归因于有效的dielectric constants中的变化， epsilon^GB_/d反映了dielectric constant作为substrates使用的dielectric constant的场强度对。在Flux Flow Oscilator （FFO）的情况下，电子场模块化的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（低）

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