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，正在研究高温非常规超导体中界面和缺陷处d波序参量的扰动。FRG将通过准粒子隧穿光谱法（可以观察电子表面态的局部密度）和SQUID干涉仪测量（能够直接确定表征非常规超导体的相位各向异性）来研究表面和界面处超导序参量的行为。在低温下的热导率和穿透深度测量将被用来确认和表征最近的实验所建议的二次超导相的发生，并预测发生在掺杂的非常规超导体。FRG将通过扫描隧道显微镜探索涡核中束缚态和扩展涡态的结构，这是唯一具有足够电子灵敏度和空间分辨率的探针，可以绘制出涡核的结构。一种独特的磁扫描仪器，扫描约瑟夫森显微镜，正在开发中，以寻找在涡旋周围循环的超导电流的各向异性，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方位，这是一个重点研究小组（FRG）项目，调查高温超导领域的基本问题。FRG的高度集成的协作结构为这个复杂的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，以及与理论预测和建模的密切互动。它还提供了一个特殊的环境，培养研究生和博士后研究，通过他们在项目的研究课题和技术的全方位参与。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被证实为非常规的超导体（铜酸盐，重费米子，有机，铁酸盐，bobocarbide等）有关。以及高度相关的电子系统的一般主题。

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.***