Controlled Defects on the Vortex Phases and Dynamics of High-Temperature and Conventional Amorphous Superconductors -- From DC to Microwave Frequencies

9401315叶氏技术摘要：通过系统地改变超导样品中缺陷的类型和密度，研究受控缺陷对高温超导体和常规超导体涡旋相和动力学的影响。特别是，零维、一维和二维缺陷的作用，以及它们对涡旋相和相变的相互作用，将通过测量低频(DC-10 MHz)电输运和磁性来研究。样品为点缺陷和柱状缺陷密度可控的氧化铋铜单晶。此外，还将与超导体的局域钉扎特性有关的微波涡旋动力学与在较低频率下得到的临界动力学进行比较。非技术摘要：超导体中缺陷的存在在决定其对外界电磁场的响应和对温度升高的耐受性方面起着重要作用。这项工作的主要主题是研究受控缺陷对高温超导体和常规超导体在大磁场中性能的影响。从这项研究中了解到的信息可以使这些超导体的性能在大磁场中的各种应用中得到优化，包括用于通信信号检测和处理的微波组件，以及高性能超导磁体。***

9401315 Yeh technical abstract: The effects of controlled defects on the vortex phases and dynamics of high-temperature and conventional superconductors will be investigated by systematically varying the type and density of defects in the superconducting samples. In particular, the role of zero, one, and two-dimensional defects, as well as their interplay on the vortex phases and the phase transitions, will be studied by measurements of low-frequency (dc- 10 MHz) electrical transport and magnetic properties. The samples are yttrium barium copper oxide single crystals with controlled densities of point and columnar defects. In addition, the microwave vortex dynamics associated with the local pinning properties of superconductors wil be compared with the critical dynamics obtained at lower frequencies. Non-technical abstract: The presence of defects in superconductors plays an important role in determining their response to external electromagnetic fields and their tolerance to the increase of temperature. The main theme of this work is to investigate the effects of controlled defects on the properties of high temperature and conventional superconductors in large applied magnetic fields. Information learned from this investigation can lead to optimizarion of the properties of these superconductors for a variety of applications in large magnetic fields, including microwave components for communication signal detection and processing, as well as high performance superconducting magnets. ***