Table Of ContentSELECTED WORKS OF LOUIS NEEL
SELECTED WORKS
OF
LOUIS NEEL
Translation from the French authorized by the
CENTRE NATIONAL DE LA RECHERCHE SCIENTIFIQUE
Editor and Translation Coordinator
NICHOLAS KURTI
Department of Engineering Science
University of Oxford, U.K.
CRC Press
Taylor & Francis Group
Boca Raton London New York
CRC Press is an imprint of the
Taylor & Francis Group, an informa business
Originally published in French in 1978 by Editions du Centre National de la Recherche Scientifique as Oeuvres
Scientifiques de Louis Neel
Published 1998 by Gordon and Breach Science Publishers
Published 2019 by CRC Press
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© 1978, 1988 by Taylor & Francis Group, LLC
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ISBN 13: 978-2-88124-300-4 (hbk)
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Library of Congress Cataloguing in Publication Data
Neel, Louis, 1904
The selected works of Louis Neel
Translation of: Oeuvres Scientifiques de Louis Neel
Includes bibliographies
(cid:9)
1. Magnetism - Collected works. I Kurti, Nicholas. II Title
QC750.15.N4313 1988 538.82-12009
ISBN 2-88124-300-2
CONTENTS
Preface to the English Edition(cid:9) vii
Preface to the French Edition viixii
Louis Mel - Chronology(cid:9)
I(cid:9) General theory of magnetism(cid:9) 1
A7, A17, A40, A22, A35, C5, C29. (Translator: P. Rhodes)
II Ferrimagnetism(cid:9) 61
A6 (Translator P Johnston A70 A72 A77 A94 C4 (Translator: K. Hoselitz)
III Antiferromagnetism(cid:9) 103
A29, A112, A113, A114, A115 (Translator: J.M.D. Coey)
IV(cid:9) Magnetic interactions and their variations(cid:9) 123
A18, A23, A33, A30 (Translator. P. Johnston)
V(cid:9) Approach to saturation in ferromagnets(cid:9) 159
A62, A63, A93 (Translator: G.A. Jones)
VI(cid:9) Elementary domains; phases and modes(cid:9) 179
A52, C29, A58, A127, A85 (Translator: R.D. Wade)
VII Bloch and Mel walls(cid:9) 219
A50, A97, A118 (Translator: R.D. Wade)
VIII Weak fields and anhysteretic magnetization(cid:9) 239
A45, A44, A47, A48, A144 (Translator: G.A. Jones)
IX(cid:9) Coercive force; magnets(cid:9) 271
Bl, A51, A57, A59, A60, A91 (Translator: K. Hoselitz)
X(cid:9) Random fields; reptation and tilting(cid:9) 313
A101, A102, A106, A107, A109, A108 (Translator: E. Geissler)
XI(cid:9) Magnetic after-effects(cid:9) 341
A73, A78, A84 (Translator: P.W. Readman)
XII(cid:9) Directional order; irradiation(cid:9) 385
A92, A119 (Translator: E. Geissler)
XIII Rocks and baked clays(cid:9) 405
A6 (Translator: J.M. Coey), C2 (originally published in English)
XIV Surface problems(cid:9) 457
A121, A122 (Translator: R.J. Nicholas)
XV Antiferromagnetic hysteresis(cid:9) 467
A142 (Translator: R.J. Nicholas)
XVI Apparatus and Techniques(cid:9) 489
All, A31, A39 (Translator: R.I. Nicholas)
XVII Experimental work (cid:9) 497
A7, A9, A20, A36 (Translator: R.J. Nicholas)
Index(cid:9) 519
PREFACE TO THE ENGLISH EDITION
I have the greatest admiration for Neel's scientific work and I am glad to supplement, on the occasion
of this English edition of Neel's papers, Professor Chabal's Preface. Neel added two new varieties of-
magnetism, antiferro- and ferrimagnetism, to the three previously existing types, namely dia-, para-, and
ferromagnetism, and he did so with the elegant simplicity and truly physical intuition that is the hallmark
of his work. It is comforting to encounter such qualities in these days of giant accelerators and com-
puters.
Quite a few years ago I wrote an article entitled `Nonmathematical Theoretical Physics' on the general
theme that most of the important discoveries in theoretical physics were the result of the use of a new
and imaginative, but essentially simple, concept that had eluded others. As an example, I told the story
of what happened when I was writing my book Electric and Magnetic Susceptibilities in the early 1930s.
It was well known at that time that a positive exchange integral can produce ferromagnetism, so, in my
book, I correctly emphasized the fact that a negative exchange integral can produce antiferromagnetic
ordering; I therefore wrote in my later review article that it was left to Noel to have the perspicacity to
propose antiferromagnetic ordering. I reproach myself to this day for not having thought of it myself,
though it is some consolation that the idea eluded all the specialists in ferromagnetism. I might also men-
tion that the concept of antiferromagnetic ordering could have been introduced as early as 1907 by means
of the negative Weiss molecular field constant.
In my review article I also emphasized the fact that many of the great theoretical discoveries were
the result of supreme physical insight rather than of rigid mathematical formalism. To understand Pauli's
exclusion principle no knowledge of arithmetic is necessary, an ability to count is sufficient. It is true
that Noel's studies of the saturation magnetization of ferrites and other ferrimagnetic materials also re-
quired an ability to add and subtract, however, having had the imagination and the courage to propose,
well before it could be proved experimentally, that the ferrites have inverse spinel structure.
Neel's work helps to maintain and, indeed, to enhance the distinguished position in the field of mag-
netism occupied by France for many years, as exemplified by names like AmpOre, Pierre Curie, Lan-
gevin, Weiss, Jean Becquerel, Brillouin, Kastler and Neel. The name of the Place de l'Etoile may be
changed, but 'Curie-point' and 'Neel-point' will forever belong in the terminology of physics.
J.H. van Vleck
Editor's Note
At the end of August 1980, when plans for this book were taking shape, I wrote to Professor J.H. van
Vleck, a good and old colleague of Professor Neel's, to ask him whether he would be willing to write
an additional preface to the English edition of Neel's scientific work. In his reply, dated September 20,
1980, van Vleck said that at the age of 81 he was trying to keep all new commitments to a minimum but
suggested that I could use as the basis of a preface the tribute he sent on the occasion of Neel's Nobel
prize (see Bull. Soc. Francaise de Physique, April-May 1971).
Professor van Vleck died on 27 October 1980 and did not see the draft of this preface. But it was
clearly his wish to be associated with this volume which, it is hoped, will be regarded by the English
speaking physics community as a modest but grateful and warm tribute to Professor Neel.
vii
PREFACE TO THE FRENCH EDITION
The broad outlines of Louis Neel's scientific work are generally well known, not only to physicists but
also to the public thanks to the awarding of the 1970 Nobel Prize in Physics to this brilliant physicist.
The publication by the CNRS of this collection of Louis Neel's works makes it possible to gain a more
intimate knowledge of the development of his scientific ideas.The reader can thus grasp an entire cross-
section of scientific research and experience the writing of an important page of science.
All the characteristics of a great scientist's development emerge from this collection. First, the urge
to understand the innermost behaviour of matter, rejecting all dogmatism and perceiving the phenomena
as they should be on the microscopic scale; hence, the theory of antiferromagnetism. Then the increas-
ing concern about sticking to personal reality and the experimental search for materials with new proper-
ties; here we have the ferrimagnetic substances. And,finally, the translation of these ideas to the world
outside physics, leading to applications in many fields. Thus, Louis Noel made important contributions
to the interpretation of the magnetic memory of rocks, which ultimately provided a key to the
phenomenon of continental drift. He also devised, at the beginning of World War II, a method of
degaussing ships, which was used unsuccessfully to protect the French fleet against magnetic mines.
This sketch, brief as it is, of an impressive list of achievements may at least bring out the various facets
of Louis Neel's scientific influence.
I do not wish to anticipate the unfolding of the progress of Louis Neel's thoughts; however, at his re-
quest, I should like to recall the different roles of the CNRS in the blossoming of his remarkable career.
As early as 1931, when he was a young research worker in Pierre Weiss's laboratory in Strasbourg, Louis
Neel was awarded a research bursary by the Caisse Nationale des Sciences, the precursor of the CNRS.
Such grants were made to encourage and facilitate the scientific work of young research workers in im-
portant laboratories.
When Neel settled in Grenoble after the 1940 armistice, the CNRS continued tosupport him in his
endeavour to start new experiments. In 1945, the CNRS decided to put this support on an institutional
basis by creating a laboratory of electrostatics and metal physics and making him its rust director.
The way the CNRS acts in developing scientific research can well be exemplified by the successive
stages of a career. It all begins with finding a young scientific talent whom the CNRS provides with the
means of developing his own research, possibly by appointing him to a full-time research post and plac-
ing him with a group renowned for the quality of its scientific output. As the research initiated by the
research worker achieves international influence, the CNRS makes its support institutional by creating
first a research team and then, possibly, a laboratory. Finally, when the research requirements demand
it, the CNRS undertakes the introduction of big scientific equipment. Thus, in Grenoble, in the environ-
ment of solid state physics laboratories, the CNRS established a national centre for intense magnetic
fields and participated in setting up the high neutron flux reactor of the Laue-Langevin Institute.
Such a development of scientific research does not come about spontaneously, it is the result of long
perseverance maintained despite the often conflicting trends set by the CNRS, which relies on the best
scientists to define and realize a policy. Here Neel showed organizational talents fully up to the level of
his scientific achievements.
By accepting heavier and heavier responsibilities for science policy and administration, Louis Neel
built up the scientific complex of Grenoble, indisputably one of the top centres of scientific research in
France. In 1939 he became chargé de mission to advise the management of the CNRS. From 1949 to
viii
1970 he was a member of the national committee for scientific research and of the Directoire, later the
Council of Administration of CNRS.
I hope that I have clearly demonstrated, in accordance with Louis Neel's wishes, the symbiosis of his
work and the actions of the CNRS. The development of the function of research is a complex process
that is achieved thanks to the researchers, the administrators, and the batisseurs. Louis Neel managed to
fulfil these functions remarkably in each case, and I now leave it to the reader to rediscover the most in-
dividual aspects of the work of a great French scientist.
Robert Chabbal
Directeur General du CNRS
(Translation by N. Kurti)
ix
