Theoretical Studies of Josephson Arrays, High-Temperature Superconductors, and Inhomogeneous Media

理论研究将在三个材料研究领域进行：(1)超导阵列及相关材料的物理：(2)铜系高温超导体中的涨落和不均匀；(3)宏观非均匀材料的线性和非线性响应。超导阵列是超导体的排列，它们通过约瑟夫森或邻近效应相互作用弱耦合在一起。它们具有广泛的潜在应用，也是超导薄膜的良好模型。在这一领域，将继续研究耦合到谐振腔的欠阻尼约瑟夫森阵列。此外，还将研究阵列和薄膜中磁通运动产生的噪声，以及超导阵列可以锁定到相干态的条件。最后，我们将研究超导阵列、薄膜和更小的结群中的量子效应。对欠掺杂高温超导材料的太赫兹吸收模型进行了研究。由于晶界限制了临界电流，因此还需要研究高温超导体ab面上的小角度晶界模型。还将研究这些材料的c轴电流-电压特性，以及控制约瑟夫森等离子体共振在大多数各向异性材料中的位置和宽度的条件。此外，最近对零温涡旋晶格的量子熔化的计算也将与实验进行比较。PI还将把最近关于宏观非均匀介质的工作扩展到磁性复合材料的研究。这里要解决的问题包括具有铁磁区结构的材料中的非均匀电导张量引起的磁阻，以及通过非磁性层耦合的磁性多层膜的行为，这将通过一个类似于层状超导体的Lawrence-Doniach处理的模型来研究。最后，PI将研究包含在光学微腔中的微小金属和介电粒子集合的电磁响应。该研究涉及凝聚态物理中的几个基本问题的研究，并可能导致广泛的技术应用。它还将通过培养研究生和博士后，为科技人力资源做出贡献。%的理论研究将在三个材料研究领域进行：(1)超导阵列及相关材料的物理：(2)铜系高温超导体中的涨落和不均匀；(3)宏观非均匀材料的线性和非线性响应。这项研究涉及凝聚态物理中的几个基本问题的研究，并可能导致广泛的技术应用。它还将通过培训研究生和博士后研究员，为科技人力资源作出贡献。*

0104987StroudTheoretical research will be conducted in three areas of materials research: (1) the physics of superconducting arrays and related materials: (2) fluctuations and inhomogeneities in cuprate-based high temperature superconductors; (3) linear and nonlinear response of macroscopically inhomogeneous materials. Superconducting arrays are arrangements of superconductors which are weakly coupled together by Josephson or proximity-effect interactions. They have a wide variety of potential applications and are also good models for superconducting thin films. In this area continued study of underdamped Josephson arrays coupled to a resonant cavity will be carried out. In addition, a study of noise produced by magnetic flux motion in arrays and films will also be undertaken, as well as a study of conditions under which a superconducting array can lock into a coherent state. Finally, a study will be made of quantum effects in superconducting arrays, films and smaller groups of junctions. Models for terahertz absorption in the underdoped high temperature superconducting materials will be studied. Also to be investigated are models of low-angle grain boundaries in the ab-planes of the high temperature superconductors, since grain boundaries limit the critical current. The c-axis current-voltage characteristics of these materials will also be investigated, as well as the conditions governing the position and width of the Josephson plasmon resonance in the most anisotropic materials. Also, recent calculations o fquantum melting of the vortex lattice at zero temperature will be compared to experiment. The PI will also extend recent work on macroscopically inhomogeneous media to the study of magnetic composites. Here the problems to be addressed include magnetoresistance arising from the inhomogeneous conductivity tensor in a material with a ferromagnetic domain structure, and the behavior of magnetic multilayers coupled through nonmagnetic layers, which will be studied by a model analogous to the Lawrence-Doniach treatment of layered superconductors. Finally, the PI will study the electromagnetic response of collections of small metal and dielectric particles contained in an optical microcavity.The research involves studies of several fundamental questions in condensed matter physics, and may lead to a wide variety of technological applications. It will also contribute to human resources in science and technology by training graduate students and postdoctoral fellows.%%%Theoretical research will be conducted in three areas of materials research: (1) the physics of superconducting arrays and related materials: (2) fluctuations and inhomogeneities in cuprate-based high temperature superconductors; (3) linear and nonlinear response of macroscopically inhomogeneous materials. The research involves studies of several fundamental questions in condensed matter physics, and may lead to a wide variety of technological applications. It will also contribute to human resources in science and technology by training graduate students and postdoctoral fellows.***