High Tc Copper Oxide Superconductors And Related Novel Materials

Authored by many of the world's leading experts on high-Tc superconductivity, this volume presents a panorama of ongoing research in the field, as well as insights into related multifunctional materials. The contributions cover many different and complementary aspects of the physics and materials challenges, with an emphasis on superconducting materials that have emerged since the discovery of the cuprate superconductors, for example pnictides, MgB2, H2S and other hydrides. Special attention is also paid to interface superconductivity. In addition to superconductors, the volume also addresses materials related to polar and multifunctional ground states, another class of materials that owes its discovery to Prof. Müller's ground-breaking research on SrTiO3.

Superconductivity is the ability of certain materials to conduct electrical current with no resistance and extremely low losses. High temperature superconductors, such as La2-xSrxCuOx (Tc=40K) and YBa2Cu3O7-x (Tc=90K), were discovered in 1987 and have been actively studied since. In spite of an intense world-wide research, a complete understanding of the copper oxide (cuprate) materials is still lacking. Many fundamental questions are unanswered, particularly the mechanism by which high-Tc superconductivity occurs. More broadly, the cuprates are in a class of solids with strong electron-electron interactions. An understanding of such 'strongly correlated' solids is perhaps the major unsolved problem of condensed matter physics with over ten thousand researchers working on this topic. High-Tc superconductors also have significant potential for applications in technologies ranging from electric power generation and transmission to digital electronics. This ability to carry large amounts of current can be applied to electric power devices such as motors and generators, and to electricity transmission in power lines. For example, superconductors can carry as much as 100 times the amount of electricity of ordinary copper or aluminium wires of the same size. This Publication presents new research on yttrium barium copper oxide superconductors, often abbreviated YBCO, which is a chemical compound with the formula YBa2Cu3O7. This material, a famous 'high-temperature superconductor', achieved prominence because it was the first material to superconduct above the boiling point of nitrogen. All materials developed before YBCO became superconducting only at temperatures near the boiling points of liquid helium or liquid hydrogen (Tb = 20.1 K). The significance of the discovery of YBCO is the breakthrough in the refrigerant used to cool the material to below the critical temperature.

Research into high-Tc materials demands the co-operation of physicists, chemists and materials scientists to discover the best solutions to the most important challenges presented by the field. In the fifth annual Workshop on High Temperature Superconductors and Novel Inorganic Materials Engineering, the topic is extended beyond high-Tc superconductivity to include other advanced oxide materials, mainly colossal magnetoresistance materials, which are closely related to the ceramic superconductors. This book covers the synthesis, characterisation (both structural and physical) and engineering of this class of materials.

This is an advanced textbook for graduate students and researchers wishing to learn about high temperature superconductivity in copper oxides, in particular the Kamimura-Suwa (K-S) model. Because a number of models have been proposed since the discovery of high temperature superconductivity by Bednorz and Müller in 1986, the book first explains briefly the historical development that led to the K-S model. It then focuses on the physical background necessary to understand the K-S model and on the basic principles behind various physical phenomena such as electronic structures, electrical, thermal and optical properties, and the mechanism of high temperature superconductivity.

High-Temperature Superconductors provides an up-to-date and comprehensive review of the properties of these fascinating materials. Much has been learned about the behavior and mechanism of this novel type of superconductivity over the past five years, but many questions remain unanswered. This book gives an invaluable survey which will help students and researchers to consolidate their knowledge and build upon it. A large number of illustrations and tables give valuable information for specialists. A critical comparison of different theoretical models involving strong electron correlations, spin fluctuations, phonons and excitons provides a background for understanding modern trends in the theory of high-temperature superconductivity.

The phenomenon of superconductivity - after its discovery in metals such as mercury, lead, zinc, etc. by Kamerlingh-Onnes in 19]] - has attracted many scientists. Superconductivity was described in a very satisfactory manner by the model proposed by Bardeen, Cooper and Schrieffer, and by the extensions proposed by Abrikosov, Gorkov and Eliashberg. Relations were established between superconductivity and the fundamental properties of solids, resulting in a possible upper limit of the critical temperature at about 23 K. The breakthrough that revolutionized the field was made in 1986 by Bednorz and Muller with the discovery of high-temperature superconductivity in layered copper-oxide perovskites. Today the record in transition temperature is 133 K for a Hg based cuprate system. The last decade has not only seen a revolution in the size of the critical temperature, but also in the myriads of research groups that entered the field. In addition, high-temperature superconductivity became a real interdisciplinary topic and brought together physicists, chemists and materials scientists who started to investigate the new compounds with almost all the available experimental techniques and theoretical methods. As a consequence we have witnessed an avalanche of publications which has never occurred in any field of science so far and which makes it difficult for the individual to be thoroughly informed about the relevant results and trends. Neutron scattering has outstanding properties in the elucidation of the basic properties of high-temperature superconductors.

Drawing from physics, mechanical engineering, electrical engineering, ceramics, and metallurgy, high-temperature superconductivity (HTSC) spans nearly the entire realm of materials science. This volume presents each of those disciplines at an introductory level, such that readers will ultimately be able to read the literature in the field.

With this book, we wish to honor the lifework of K. Alex Müller and present him with this book on the occasion of his 94th birthday. We are convinced that he will very much enjoy reading it. We would like to thank all contributors to this book, who addressed topics complementary and related to his work. The articles of the book represent the efforts in solid state physics – spanning more than 60 years – which have been groundbreaking in scientific and applied sciences. Many of the current hot topics are derived from this earlier work which has pioneered the way toward new experimental tools and/or refined techniques. From this point of view, the book presents, on one hand, a historical review and, on the other hand, a directory of possible future research.