Advances in Superconductivity

Transcription

1 Advances in Superconductivity

2 NATO Advanced Science Institutes Series A series of edited volumes comprising multifaceted studies of contemporary scientific issues by some of the best scientific minds in the world, assembled in cooperation with NA TO Scientific Affairs Division. This series is published by an international board of publishers in conjunction with NATO Scientific Affairs Division A Life Sciences B Physics C Mathematical and Physical Sciences D Behavioral and Social Sciences E Applied Sciences F Computer and Systems Sciences G Ecological Sciences Plenum Publishing Corporation New York and London D. Reidel Publishing Company Dordrecht, Boston, and London Martinus Nijhoff Publishers The Hague, Boston, and London Springer Verlag Heidelberg, Berlin, and New York Recent Volumes in Series B: Physics Volume 93 -Symmetries in Nuclear Structure edited by K. Abrahams, K. Allaart, and A. E. L. Dieperink Volume 94 -Quantum Optics, Experimental Gravitation, and Measurement Theory edited by Pierre Meystre and Marian O. Scully Volume 95 -Advances in Laser Spectroscopy edited by F. T. Arecchi, F. Strumia, and H. Walther Volume 96 -Atomic Physics of Highly Ionized Atoms edited by Richard Marrus Volume 97 -Mass Transport in Solids edited by F. Beniere and C. R. A. Catlow Volume 98 -Quantum Metrology and Fundamental Physical Constants edited by Paul H. Cutler and Amand A. Lucas Volume 99 -Techniques and Concepts in High-Energy Physics II edited by Thomas Ferbel Volume too-advances in Superconductivity edited by B. Deaver and John Ruvalds

3 Advances in Su percond uct ivity Edited by B. Deaver and John Ruvalds University of Virginia Charlottesville, Virginia Plenum Press New York and London Published in cooperation with NATO Scientific Affairs Division

4 Proceedings of a NATO Advanced Study Institute on Advances in Superconductivity, held July 3-15, 1982, at the Ettore Majorana Cer:ltre for Scientific Culture, Erice, Sicily, Italy Library of Congress Cataloging in Publication Data NATO Advanced Study Institute on Advances in Superconductivity (1982: Erice, Italy) Advances in superconductivity. (NATO advanced science institutes series. Series B, Physics; v. 100) Published in cooperation with NATO Scientific Affairs Division." "Proceedings of a NATO Advanced Study Institute on Advances in Superconductivity, held July 3-15, 1982, at the Ettore Majorana Centre for Scientific Culture, Erice, Sicily, Italy"-T.p. verso. Includes bibliographical references and index. 1. Superconductivity-Congresses. I. Deaver, Bascom Sine, II. Ruvalds, J. III. North Atlantic Treaty Organization. Scientific Affairs Division. IV. Title. V. Series. QC612.S8N ' ISBN ISBN (ebook) DOI / Plenum Press, New York Softcover reprint of the hardcover 1st edition 1983 A Division of Plenum Publishing Corporation 233 Spring Street, New York, N.Y All rights reserved. No part of this book may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, microfilming, recording, or otherwise, without written permission from the Publisher

5 PREFACE The Advanced Study Institute on "Advances in Superconductivity" was held at the Ettore Majorana Centre for Scientific Culture in Erice, Sicily, during July 3 to July 15, This Institute was the third course of the International School of Low Temperature Physics, which was established at the Centre in 1977 with the guidance and inspiration of T. Regge and A. Zichichi. The 1982 Course was centered on a topic which brought together fundamental basic research and the most recent promising technological applications. Accordingly, the participants represented a wide spectrum of industrial and government laboratories, as well as universities from various countries. The program of topics and speakers was developed with the advice of the Organizing Committee, composed of H. Frohlich, T. Regge, B. Stritzker, and L. Testardi. This Institute emphasized recent developments in the science and technology of superconductivity. A historical perspective was provided by H. Frohlich, whose lectures recall the earliest discoveries and theoretical attempts to understand superconductivity. Ironically, his early suggestion of the electron-phonon coupling as a key to superconductivity was met with initial widespread skepticism. Later, the development of field theory methods for solid state physics problems, and the evolution of the BCS theory has led to a seemingly unanimous concensus regarding the e1ectronphonon mechanism as the predominant source of superconductivity in known materials. Experimental studies of superconductivity exemplify the strong interplay of science and technology in many ways. The discovery in 1911 of zero resistance in Hg at temperatures below 4 K generated excitement in the potential applications of superconducting coils to be used as windings in magnets, but this hope was set back for several decades by the realization that strong magnetic fields destroy the superconducting state. As the availability of low temperature facilities grew, higher superconducting temperatures were found, with Tc = 15 K of NbN discovered in Naturally, the proximity of this Tc range to the reach of pumped liquid hydrogen caused a flurry of interest. By 1970, approximately 1000 materials were known to become superconducting, with some v

6 PREFACE having Tc values near 20 o K, and many exhibiting the capability of withstanding strong magnetic fields. A remarkable number of these technologically important materials were discovered by B. T. Matthias, using an intuitive approach which yielded empirical rules relating Tc to the electron/atom ratio in transition metal compounds. A quantitative theoretical basis for the Matthias rules remains a challenge. At present, the technological advances are in the forefront of superconductivity research. Giant high field magnets are being developed for large scale applications such as fusion energy, high energy accelerators, and train levitation. At the other extreme, miniature superconducting circuits using the Josephson effect are being used as ultrasensitive magnetometers in biological systems and other weak signal detection applications. Finally, the superconducting microcircuitry now promises to be the key to the next generation of sophisticated high-speed computers. The highlights of these technological applications, together with fundamental advances in the discovery and understanding of new superconducting materials forms the basis far this book. Aside from the scientific programme of the Institute, it was memorable for its location and facilities. The Ettore Majorana Centre for Scientific Culture, with the gracious leadership of Director A. Zichichi, hosts schools and institutes in many disciplines each year, a large number of them returning periodically. The beauty of Erice, the warmth of its people, the comfort of the living arrangements and efficiency of the Centre's staff were important factors contributing to the success of the School. The administrative contributions and guidance of N. McLaughlin were especially appreciated by all participants. We are grateful to several organizations for financial assistance. The Scientific Affairs Division of NATO awarded a grant that was crucial in bringing all of the lecturers and many of the seminar speakers and students from Europe and North America. The Italian government, through its Ministries of Education and of Scientific Research, the Italian Research Council, and the Sicilian Regional Government, gave support for several students' travel and local expenses, and provided for the Centre's facilities and staff. The U.S. National Science Foundation and the European Physical Society provided student fellowships. Finally, it is a pleasure to express our appreciation to Jean Dozier at the University of Virginia, whose organization and preparation assistance played an essential role throughout the three years of planning and completion of the Institute and this volume. B. Deaver and J. Ruvalds Editors

7 CONTENTS History of the Theory of Superconductivity H. Frohlich Fundamental Limits on Squid Technology J. Clarke Josephson Computer Technology H. H. Zappe Organic Superconductivity D. Jerome Solitions in Long Josephson Junctions N. F. Pedersen Josephson Effects: Basic Concepts A. Barone and G. Paterno Investigations on the Josephson Effect by Photosensitive Tunnel Structures A. Barone and M. Russo The Problem of Geometrical Configuration in Josephson Junctions A. Barone and R. Vaglio Workshop on Organic Materials and Superconducting Fluctuations R. L. Greene, H. Gutfreund and M. Weger Superconducting Tunnel Junctions in High Frequency Radiation Detectors T. Claeson Coexistence of Superconductivity and Magnetism M. B. Maple VII

8 viii CONTENTS Ion Implantation - A Promising Technique for the Production of New Superconducting Materials B. Stritzker Empirical Approach to Superconductivity T. H. Geballe Kosterlitz-Thouless Transitions and Two- Dimensional Superconductors J. E. Mooij Re-entrant Superconductivity J. Ruvalds Scientific Program. 515 Participants. 519 Index