The recent discovery of high-temperature superconductivity has resulted in a remarkable growth in the amount of research and the number of researchers working in this exciting field. Superconductivity is not a new phenomenon: in 1991 it will be 80 years old. Even though it was the newer discoveries which motivated us to write this book, the book itself is mainly a description of the fundamentals of the phenomenon. The book is written for a very broad audience, including students, engin eers, teachers, scientists, and others who are interested in learning about this exciting frontier of science. We have focused on the qualitative aspects, so that the reader can develop a basic understanding of the fundamental physics without getting bogged down in the details. Because of this approach, our list of refer ences is not comprehensive, and it is supplemented with a summary of additional reading consisting of monographs and selected review articles. (The articles we have referenced were either not reflected in the review articles on monographs or were milestones in the development of the field. ) In addition, some of the sections which can be skipped during the first reading have been marked with asterisks (*). Until recently, superconductivity was considered to belong to the field of low-temperature physics. This field was born, simultaneously with quantum physics, at the beginning of this century. Initially these two contemporaneous fields developed independently, but they soon became strongly coupled."

Stuart Wolf This book originated as a series of lectures that were given as part of a Summer School on Spintronics in the end of August, 1998 at Lake Tahoe, Nevada. It has taken some time to get these lectures in a form suitable for this book and so the process has been an iterative one to provide current information on the topics that are covered. There are some topics that have developed in the intervening years and we have tried to at least alert the readers to them in the Introduction where a rather complete set of references is provided to the current state of the art. The field of magnetism, once thought to be dead or dying, has seen a remarkable rebirth in the last decade and promises to get even more important as we enter the new millennium. This rebirth is due to some very new insight into how the spin degree of freedom of both electrons and nucleons can play a role in a new type of electronics that utilizes the spin in addition to or in place of the charge. For this new field to mature and prosper, it is important that students and postdoctoral fellows have access to the appropriate literature that can give them a sound basis in the funda mentals of this new field and I hope that this book is a very good start in this direction."

The Conference on the Science and Technology of Thin Film Superconductors was conceived in the early part of 1988 as a forum for the specialist in thin film superconductivity. The conference was held on November 14-18, 1988, in Co lorado Springs, Co lorado. Al though many excellent superconductivity conferences had been convened in the wake of the 1986-1987 discoveries in high temperature superconductivity, thin film topics were often dispersed among the sessions of a more general conference agenda. The response to the Conference on the Science and Technology of Thin Film Superconductors confirmed the need for an extended conference devoted to thin film superconductors. These proceedings are a major contribution to the technnology of thin film superconductivity because of the breadth and quality of the articles provided by leaders in the field. The proceedings are divided into articles on laser deposition, sputtering, evaporation, metal organic chemical vapor deposition, thick film, substrate studies, characterization, patterning and applications, and general properties. Most of the articles discuss scientific issues for high temperature thin film superconductors, although the conference was to be a forum for technology and scientific questions for both low and high temperature superconductivity. For the first day of the 5 day conference, Lawrence Berkeley Laboratory had organized an excellent set of short courses in superconduc t ing thin film devices.

Since the discovery in 1986 of high temperature superconductors by J. G. Bednorz and K. A. Muller, a considerable progress has been made and several important scientific problems have emerged. Within this NATO Advanced Study Institute our intention was to focus mainly on the controversial topic of the symmetry of the superconducting gap and given the very short coherence length, the role of fluctuations. The Institute on 'The Gap Symmetry and Fluctuations in High- Superconductors' took place in the "Institut d'Etudes Scientifiques de Cargese" in Corsica, France, between 1 - 13 September 1997. The 110 participantsfrom 18 countries (yet 30 nationalities) including 23 full time lecturers, have spent two memorable weeks in this charming Mediterranean resort. All lecturers were asked to prepare pedagogical papers to clearly present the central physical idea behind specific model or experiment. The better understanding of physics of high temperature superconductivity is certainly needed to guide the development of applications of these materials in high and weak current devices.

The recent discovery of high-temperature superconductivity has resulted in a remarkable growth in the amount of research and the number of researchers working in this exciting field. Superconductivity is not a new phenomenon: in 1991 it will be 80 years old. Even though it was the newer discoveries which motivated us to write this book, the book itself is mainly a description of the fundamentals of the phenomenon. The book is written for a very broad audience, including students, engin eers, teachers, scientists, and others who are interested in learning about this exciting frontier of science. We have focused on the qualitative aspects, so that the reader can develop a basic understanding of the fundamental physics without getting bogged down in the details. Because of this approach, our list of refer ences is not comprehensive, and it is supplemented with a summary of additional reading consisting of monographs and selected review articles. (The articles we have referenced were either not reflected in the review articles on monographs or were milestones in the development of the field. ) In addition, some of the sections which can be skipped during the first reading have been marked with asterisks (*). Until recently, superconductivity was considered to belong to the field of low-temperature physics. This field was born, simultaneously with quantum physics, at the beginning of this century. Initially these two contemporaneous fields developed independently, but they soon became strongly coupled."

Stuart Wolf This book originated as a series of lectures that were given as part of a Summer School on Spintronics in the end of August, 1998 at Lake Tahoe, Nevada. It has taken some time to get these lectures in a form suitable for this book and so the process has been an iterative one to provide current information on the topics that are covered. There are some topics that have developed in the intervening years and we have tried to at least alert the readers to them in the Introduction where a rather complete set of references is provided to the current state of the art. The field of magnetism, once thought to be dead or dying, has seen a remarkable rebirth in the last decade and promises to get even more important as we enter the new millennium. This rebirth is due to some very new insight into how the spin degree of freedom of both electrons and nucleons can play a role in a new type of electronics that utilizes the spin in addition to or in place of the charge. For this new field to mature and prosper, it is important that students and postdoctoral fellows have access to the appropriate literature that can give them a sound basis in the funda mentals of this new field and I hope that this book is a very good start in this direction.

The Novel Mechanisms of Superconductivity Conference was initially conceived in the early part of 1986 as a small, 2-1/2 day workshop of 40-70 scientists, both theorists and experimentalists interested in exploring the possible evidence for exotic, non phononic superconductivity. Of course, the historic discoveries of high temperature oxide superconductors by Bednorz and Mftller and the subsequent enhancements by the Houston/Alabama groups made such a small conference impractical. The conference necessarily had to expand, 2-1/2 days became 4-1/2 days and superconductivity in the high Tc oxides became the largest single topic in the workshop. In fact, this conference became the first major conference on this topic and thus, these proceedings are also the first maj or publication. However, heavy fermion, organic and low carrier concentration superconductors remained a very important part of this workshop and articles by the leaders in these fields are included in these proceedings. Ultimately the workshop hosted rearly 400 scientists, students and media including representatives from the maj or research groups in the U.S., Europe, Japan and the Soviet Union.

'Superconducting State' provides a very detailed theoretical treatment of the key mechanisms of superconductivity, including the current state of the art (phonons, magnons, and plasmons). A very complete description is given of the electron-phonon mechanism responsible for superconductivity in the majority of superconducting systems, and the history of its development, as well as a detailed description of the key experimental techniques used to study the superconducting state and determine the mechanisms. In addition, there are chapters describing the discovery and properties of the key superconducting compounds that are of the most interest for science, and applications including a special chapter on the cuprate superconductors. It provides detailed treatments of some very novel aspects of superconductivity, including multiple bands (gaps), the "pseudogap" state, novel isotope effects beyond BCS, and induced superconductivity.

Superconductivity has become one of the most intensely studied physical phenomena of our times, with tremendous potential to revolutionize fields as diverse as computing and transportation. This book describes the methods, established results, and recent advances in the field. The goal is to present recently developed theoretical models in light of the long-sought aim of achieving the effect at very high temperatures. The book includes a detailed review of various mechanisms, including phononic, magnetic, and electronic models. The authors focus on the phenomenon of induced superconductivity in the high-temperature oxides, particularly the high-transition-temperature cuprates. They also discuss a variety of low-temperature superconducting systems in conventional materials and organics. The book links the crucial experiments with the most current theories, offering a unified description of the phenomenon. All researchers (and graduate-level) students involved with work in superconductivity will find this an invaluable resource, including solid-state and condensed-matter physicists and chemists, and materials scientists.