Electrodynamics Of High Temperature Superconductors

These lectures are concerned with the application of high temperature superconductors to both passive and active high-frequency devices.The central issue addressed is the electrodynamics of granular superconductors, particularly where grain boundaries (either natural or synthetic) act as Josephson weak-links. Grain boundaries are responsible for residual dissipation and for unwanted dependence of the electromagnetic properties on ambient magnetic fields and on elevated power level. Properly controlled, similar weak-links are the key to high sensitivity dc and rf SQUIDS at readily accessible temperatures, and to modulators, mixers and detectors. Such structures may conveniently lead to superconductive electronic devices as well as coherent sources of radiation in the very far infrared.

Since the 1980s, a general theme in the study of high-temperature superconductors has been to test the BCS theory and its predictions against new data. At the same time, this process has engendered new physics, new materials, and new theoretical frameworks. Remarkable advances have occurred in sample quality and in single crystals, in hole and electron doping in the development of sister compounds with lower transition temperatures, and in instruments to probe structure and dynamics. Handbook of High-Temperature Superconductvity is a comprehensive and in-depth treatment of both experimental and theoretical methodologies by the the world's top leaders in the field. The Editor, Nobel Laureate J. Robert Schrieffer, and Associate Editor James S. Brooks, have produced a unified, coherent work providing a global view of high-temperature superconductivity covering the materials, the relationships with heavy-fermion and organic systems, and the many formidable challenges that remain.

Introduction to Superconductivity differs from the first edition chiefly in Chapter 11, which has been almost completely rewritten to give a more physically-based picture of the effects arising from the long-range coherence of the electron-waves in superconductors and the operation of quantum interference devices. In this revised second edition, some further modifications have been made to the text and an extra chapter dealing with ""high-temperature"" superconductors has been added. A vast amount of research has been carried out on these since their discovery in 1986 but the results, both theoretical and experimental, have often been contradictory, and seven years later there remains little understanding of their behavior. This book comprises 14 chapters, with the first focusing on zero resistance. Succeeding chapters then discuss perfect diamagnetism; electrodynamics; the critical magnetic field; thermodynamics of the transition; the intermediate state; and transport currents in superconductors. Other chapters cover the superconducting properties of small specimens; the microscopic theory of superconductivity; tunneling and the energy gap; coherence of the electron-pair wave; the mixed state; critical currents of type-II superconductors; and high-temperature superconductors. This book will be of interest to practitioners in the fields of superconductivity and solid-state physics.

This book presents a unified and comprehensive theoretical treatment of electromagnetic, thermal and mechanical phenomena in superconductors. Introduces basic concepts and principles with particular emphasis on general methodology.

The publication of Volume V of Physical Properties of High Temperature Superconductors is expected in March, 1996. It will have chapters of interest for both fundamental studies and applied research. The topics discussed are expected to include the electromagnetic response (penetration depth and surface resistance), local lattice distortions, the influence of vortex fluctuations on macroscopic behavior, the properties of superlattices, and the symmetry of the superconducting order parameter.

Five questions dominated the ARW on Physics and Materials Science of High Temperature Superconductors, of which this book forms the permanent record. Briefly, these are: (i) How close are we to a unified theory? The consensus is that we are not. (ii) Flux pinning: can it be achieved in bulk materials? Still an open question. The following three questions are related. (iii) Can grain boundary contributions be brought under control? (iv) What is the real requirement for purity and general chemistry control? (v)What is the practical outlook for bulk products - tapes and wires? One of the conclusions is that the geometry and dimensions in thin films are the key parameters that facilitate the realization of high current densities and, consequently, their commercial application. On the other hand, the very large number of poorly understood microstructural, chemical and mechanical variables involved in the preparation of bulk materials are currently prohibiting large scale commercialization of wires and tapes.