Research of Quantum tunneling phenomena in mesoscopic Josephson superlattice

介观约瑟夫森超晶格量子隧道现象研究

基本信息

批准号：
16360147
负责人：
IRIE Akinobu
金额：
$ 9.66万
依托单位：
Utsunomiya University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2004
资助国家：
日本
起止时间：
2004 至 2006
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-16360147/
关键词：
high Te superconductor intrinsic Josephson junctions mesoscopic phenomena vortex flow SQUID magnet superconductor structure spin injection Bi_2Sr_2CaCu_2O_y vortex flow 超伝導ギャップ超伝導体接合サブミクロン帯電効果熱活性モデル

项目摘要

We studied quantum tunneling phenomena in intrinsic Josephson superlattice of (Bil-xPbx)_2Sr_2CaCu_2O_y single crystals. In this study, we obtained the following results.1. We developed the new fabricated process to make a stack of small intrinsic Josephson junctions. By using this process, samples with lateral dimensions ranging from sub-μm^2 to several tens μm^2 were successfully fabricated.2. The current-voltage characteristics of BPSCCO intrinsic Josephson junctions showed clear multiple branches with high hysteresis and a well-defined gap structure without negative resistance. The quasiparticle I-V characteristics were in agreement with the feature of a weighted, momentum-averaged d-wave model.3. At intermediate temperature the switching mechanism from zero voltage state to a finite voltage state is due to thermal activation process. At lower temperature switching current distribution became wider due to the influence of multiple switching modes.4. To analyze the vortex dynamics, the inductive coupling model taking into account thermal fluctuations was proposed. The model reproduced the previous experimental results and suggests that the out-of-phase flow of vortices is stable rather than the in-phase flow, and the oscillations of the vortex flow resistance are not directly related to the structure of the vortex lattice.5. The dc SQUIDs with in-plane loop geometry and two stacks of intrinsic Josephson junctions were successfully fabricated using the developed process. The fabricated SQUID showed clear periodic and symmetric flux-voltage characteristics due to the quantum interference between the stacks.6. The hybrid Fe/BSCCO structure was fabricated. After an application of a magnetic field, the suppression of the critical current of intrinsic Josephson junctions due to the spin injection was observed.

我们研究了（BIL-XPBX）_2SR_2CACU_2O_2O_Y单晶的内在约瑟夫森超级晶格中的量子隧道现象。在这项研究中，我们获得了以下结果1。我们开发了新的制造过程，以制造一堆固有的约瑟夫森连接。通过使用此过程，成功制造了横向尺寸的样品，范围为sub-μm^2到几个μm^2。2。 BPSCCO固有的约瑟夫森连接的电流 - 电压特性显示了具有较高磁滞和明确定义的间隙结构而没有负电阻的清晰的多个分支。准颗粒I-V特性与加权，动量平均D-WAVE模型的特征一致。3。在中等温度下，从零电压状态到有限电压状态的开关机理是由于热激活过程引起的。在较低的温度开关电流下，由于多个开关模式的影响，分布变得更宽。4。为了分析涡旋动力学，提出了考虑热波动的电感耦合模型。该模型再现了先前的实验结果，并表明涡旋的涡流流是稳定而不是同相流量，并且涡流电阻的振荡与涡旋晶格的结构无直接相关。5。使用开发过程成功制造了具有平面回路几何形状和两个内在的约瑟夫森连接的DC鱿鱼。由于堆栈之间的量子干扰，制造的鱿鱼显示出明显的周期性和对称通量电压特性。6。杂交Fe/BSCCO结构被制造。应用磁场后，观察到由于自旋注射而引起的内在约瑟夫森连接的临界电流的抑制。