Theoretical and Experimental Aspects of Valence Fluctuations and Heavy Fermions PDF
Preview Theoretical and Experimental Aspects of Valence Fluctuations and Heavy Fermions
Theoretical and Experimental Aspects of Valence Fluctuations and Heavy Fermions Theoretical and Experimental Aspects of Valence Fluctuations and Heavy Fermions Edited by L. C. Gupta and S. K. Malil< Tata Institute of Fundamental Research Bombay. India Plenum Press • New Yorl< and London Library of Congress Cataloging in Publication Data International Conference on Valence Fluctuations (5th: 1987: Bangalore, India) Theoretical and experimental aspects of valence fluctuations and heavy fermions. "Proceedings of the Fifth International Conference on Valence Fluctuations, held January 5-9,1987, in Bangalore, India"-T.p. verso. Bibliography: p. Includes index. 1. Valence fluctuations-Congresses. 2. Condensed matter-Congresses. 3. Fermions -Congresses. 4. Superconductivity-Congresses. I. Gupta, L. C. II. Malik, S. K. III. Title. QCI76.8.V34I57 1-987 537.6'23 87-25816 ISBN-13: 978-1-4612-8259-4 e-ISBN-13: 978-1-4613-0947-5 DOl: 10.1007/978-1-4613-0947-5 Proceedings of the Fifth International Conference on Valence Fluctuations, held January 5-9, 1987, in Bangalore, India © 1987 Plenum Press, New York Softcover reprint of the hardcover I st edition 1987 A Division of Plenum Publishing Corporation 233 Spring Street, New York, N.Y. 10013 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 To the memory of Ron D. Parks SPONSORS Board of Research in Nuclear Sciences, Department of Atomic Energy, Government of India Council of Scientific and Industrial Research, India Department of Electronics, Government of India Department of Science & Technology, Government of India Defence Research and Development Organization, Ministry of Defence, Government of India Indian Institute of Science, Bangalore Indian Institute of Technology, Powai, Bombay Indian National Science Academy, New Delhi Indian Rare Earths ltd. (a Government of India Undertaking), Bombay National Aeronautical laboratory, Bangalore National Physical laboratory, Delhi Saha Institute of Nuclear Physics, Calcutta Tata Institute of Fundamental Research, Bombay University Grants Commission, India INTERNATIONAL ADVISORY COMMITTEE C.N.R. Rao, Chairman, INDIA P.W. Anderson USA T. Penney USA N.B. Brandt USSR 1. A. Smirnov USSR M. Campagna FRG J.L. Smith USA B. Coqblin France F. Steglich FRG A. Jayaraman USA C.M. Varma USA G. Krill France R. Vijayaraghavan India T. Kasuya Japan P. Wachter Switzerland N. F.Mott UK O. Wohlleben FRG NATIONAL ORGANIZING COMMITTEE R. Vijayaraghavan, Chairman, Bombay M. Barma Bombay B.D. Padalia Bombay R. Chidambaram Bombay E.S. Rajagopal Bangalore H.G. Oevare Bombay J. Ramakrishna Bangalore S.K. Ghatak Kharagpur T.V. Ramakrishnan Bangalore L.C. Gupta Bombay S. Ramaseshan Bangalore S.K. Joshi Roorkee K.J. Rao Bangalore H.R. Krishnamurthy Bangalore A.K. Singh Bangalore C.K. Majumdar Calcutta B.S. Shastry Bombay S.K. Malik Bombay G.V. Subba Rao Madras R. Nagarajan Bombay Members of the panel discussions Heavy Fermions C.M. Varma (Chairperson), F. Steglich, E. Muller-Hartmann, Z. Fisk, P. Fulde, B. Batlogg, T.M. Rice Spectroscopies M. Campagna (Chairperson), G. Krill, J.W. Allen, N. Martensson, B. Johansson, D.O. Sarma viii FOREWORD During the Koln meeting (August 28-31, 1984), Irdia was chosen as the venue for the next International Conference on Valence Fluctuations. lhis was in recognition ard appreciation of the work done, both experimental ard theoretical, by the Irdian scientists in this area during the last decade. We decided to hold this Conference in the month of January, 1987 at Bangalore. lhe subject of Valence Fluctuations has kept itself alive ard active as it has provided many shocks ard suprises particularly among the Ce- ard U-based intermetallies. lhe richness of many interesting physical phenomena occurring in mixed valent materials, the flexibility of modifying their physical properties (by alloying, for example) ard the possibility of synthesizing a wide variety of new such materials seem to be the key factors in this regard. Barely six months before this Conference, an International Conference on Anomalous Rare Earths and Actinides (ICAREA) had been held at Grenoble (July, 1986) which also focussed on mixed valence ard heavy fermion phenomena. In spite of this, the response to this' Conference was very enthusiastic and encouraging. Many interesting ard important results were presented at this Conference which have been included in this volume. lhe recently discovered phenomenon of high-T supercorductivity in certain cuperates also figured at this Conference. ~ecognizing that this is a great event in cordensed matter physics, we deviated from the printed programme of the Conference ard organized informal discussions on high-Tc superconductivity on the very first day of the Conference. Presumably the discovery of bulk high-T supercorductivity in single phase systems of t'le type La M Cu04 waS anRounced for the first time at this International Conferente~ Xlt is believed that mixed valence of copper is crucial for extraordinary high T (~40K in La2Cu04_~ ard ~.9?K i~ YBa2Cu307_~) .i~ these systems. It h~s transformed superConduct1.V1.ty wto a troly exc1.t1.ng research activity ard a highly promising technology. In subsequent Conferences on Valence Fluctuations and on Supercorductivity, mixed valence of copper will certainly receive a great deal of attention. lhe Conference received generous support from several funding agencies and the National Institutions of the Government of India. Needless to say, without their support, it would not have been possible to 'organize ard run this Conference. We are very grateful to these organizations. We thank the Director, T.I.F.R, Bombay for guiding ard allowing us to use the T.I.F.R. facilities for the Conference purposes. Prof. C.N.R. Rao, Director, LLSc., Bangalore, kirdly agreed to be the Chairman of the International Advisory Committee of this Conference. We are, grateful to all the members of this Committee for their suggestions and help in the organization of the scientific programme. We ix x FOREWORD thank all the overseas and Indian participants who attended the Conference in large numbers and contributed to the success of the Conference. We are thankful to the members of the National Committee who have helped us in many ways in running the Conference efficiently. In the passing away of Ron D. Parks, the scientific community has suffered a great loss. It was he who organized the first International Conference of this series at Rochester in 1976 viz. "Valence Instabilities and Related Narrow Band Phenomena". We dedicate this volume to his memory. R. Vijayaraghavan Chairman, National Committee PREFACE The Fifth International Conference on Valence Fluctuations was held during January 5-9, 1987 at the Hotel Ashok, Bangalore, India. The proceedings opened with the inaugural address by Prof. B.V. Sreekantan, Director of Tata Institute of Fundamental Research. Prof. P.W. Anderson delivered the keynote address 'Where are we in the mixed valence story?' . The pattern of the Conference was similar to that of the Fourth International Conference on Valence Fluctuations held at Koln in 1984. Thirty nine invited talks were presented at this Conference covering important aspects of Valence Fluctuations and Heavy Fermion Systems. This volume contains thirty seven invited papers. Out of one hundred and ten contributory papers, presented as posters, eighty seven appear in this volume. All the papers, invited as well as contributory, appearing in this volume have been refereed. We express our deep gratitude to the referees of the papers for their efforts. Panel discussions were organized on 'Heavy Fermions' and 'Spectroscopies'. The list of panelists who participated in these discussions appears on page v. J.L. Smith of Los Alamos and T. Kasuya of Tohoku University, did an excellent job in summarlzlng the experimental and theoretical work reported at the Conference. We appreciate their effort in highlighting the achievements of the Conference. During the Conference, we heard about the discovery of high-T superconductivity (T ~ 36K) in single phase materials of the typ~ La _xM CuO 0 (M = Ca, Sr, Ba). Just before the concluding session, Prof. P.~. Ande¥son presented his theory of superconductivity in these systems. An abstract of his talk appears on page nine. The members of our staff, R.S. Chaughule, D.R. Gokhale, N.S. Kurup and M.R. Shinde worked very hard for many months and it is entirely due to their unrelenting efforts that we could bring up this volume. Several members of the Solid State Physics Group have also worked patiently before and after the Conference. Their cooperation and help is gratefully acknowledged. Our colleague R. Nagarajan deserves a special mention for his keen interest in the whole project. His contributions have been too many to enumerate here. Ms. Ellen Raynor-Enco of Plenum press, New York, has been very kind in providing us with many helpful suggestions regarding the preparation of this volume. It is possible that, due to our oversight, we might have forgotten to acknowledge our gratitude to some other colleagues. We would like to be excused for an unintentional lapse. xi xii PREFACE Prof. R. Vijayaraghavan, the Chairman of the National Committee of this Conference has been our main source of inspiration throughout this effort. It is only because of his encouragement that we could fulfil our committment. We are very grateful to him. 15 June, 1987 L. C. Gupta BOMBAY S. K. Malik
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