FRG: Fragility of the d-wave Order Parameter at Interfaces and Defects in High Temperature Superconductors

这是一个重点研究小组（FRG）的项目，该项目正在研究高温非常规超导体界面和缺陷处d波阶参数的扰动。FRG将通过准粒子隧道光谱（可以观察电子表面态的局部密度）和SQUID干涉仪测量（可以直接确定非常规超导体的相位各向异性）来研究表面和界面上超导有序参数的行为。低温下的热导率和穿透深度测量将用于确认和表征最近实验提出的并预测在掺杂非常规超导体中发生的二次超导体相的开始。FRG将通过扫描隧道显微镜探索涡旋核心中束缚和扩展涡旋状态的结构，这是唯一具有足够电子灵敏度和空间分辨率来绘制涡旋核心结构的探针。一种独特的磁扫描仪器，扫描约瑟夫森显微镜，正在开发中，以寻找涡旋周围循环超电流的各向异性，这是非常规超导体中涡旋的另一个重要特征。FRG为培养研究生和博士后研究提供了一个特殊的环境，通过他们参与项目的研究主题和技术的全频谱%%%这是一个重点研究小组（FRG）项目，研究高温超导领域的基本问题。FRG的协作性高度集成结构为这一复杂问题提供了有效的方法，允许合并高质量的样本，强大的独特实验探针，并与理论预测和建模密切互动。它还为培养研究生和博士后研究提供了一个特殊的环境，通过他们参与项目的研究主题和技术的全谱。这里讨论的问题在凝聚态物理学中具有极大的兴趣和重要性，因为它们与越来越多的超导体（铜、重费米子、有机、钌酸盐、碳化硼等）和高度相关电子系统的一般主题相关

This is a Focused Research Group (FRG) project which is investigating the perturbation of the d-wave order parameter at interfaces and defects in high temperature, unconventional superconductors. The FRG will investigate the behavior of the superconducting order parameter at surfaces and interfaces by quasiparticle tunneling spectroscopy that can look at the local density of electronic surface states, and by SQUID interferometer measurements capable of determining directly the phase anisotropy that characterizes unconventional superconductors. Thermal conductivity and penetration depth measurements at low temperatures will be used to confirm and characterize the onset of secondary superconductor phases suggested by recent experiments and predicted to occur in doped unconventional superconductors. The FRG will explore the structure of bound and extended vortex states in the vortex core by scanning tunneling microscopy, the only probe with sufficient electronic sensitivity and spatial resolution to map out the structure of the vortex core. A unique magnetic scanning instrument, the scanning Josephson microscope, is being developed to search for the anisotropy of the circulating supercurrents around the vortex, another important feature of vortices in unconventional superconductors. The FRG provides a special environment for training graduate student and postdoctoral research through their involvement in the full spectrum of the project's research topics and techniques%%%This is a Focused Research Group (FRG) project which investigates fundamental questions in the field of high-temperature superconductivity. The collaborative highly integrated structure of the FRG provides and effective approach to this complex problem, allowing a merging of high-quality samples, powerful unique experimental probes, and close interactions with theoretical predications and modeling. It also provides a special environment for training graduate student and postdoctoral research through their involvement in the full spectrum of the project's research topics and techniques. The issues addressed here are of great interest and importance in condensed matter physics because of their relevance to the growing list of superconductors confirmed to be unconventional (cuprate, heavy fermion, organic, ruthenate, bobocarbide, etc.) and to the general subject of highly correlated electron systems.***