Néel in 1970
Louis Eugène Félix Néel
22 November 1904
|Died||17 November 2000 (aged 95)|
|Alma mater||École Normale Supérieure, University of Paris|
University of Strasbourg
|Doctoral advisor||Pierre Weiss|
Néel studied at the Lycée du Parc in Lyon and was accepted at the École Normale Supérieure in Paris. He obtained the degree of Doctor of Science at the University of Strasbourg. He was corecipient (with the Swedish astrophysicist Hannes Alfvén) of the Nobel Prize for Physics in 1970 for his pioneering studies of the magnetic properties of solids. His contributions to solid state physics have found numerous useful applications, particularly in the development of improved computer memory units. About 1930 he suggested that a new form of magnetic behavior might exist; called antiferromagnetism, as opposed to ferromagnetism. Above a certain temperature (the Néel temperature) this behaviour stops. Néel pointed out (1948) that materials could also exist showing ferrimagnetism. Néel has also given an explanation of the weak magnetism of certain rocks, making possible the study of the history of Earth's magnetic field.
Néel received numerous awards and honours for his work including:
Owing to his involvement in national defense, particularly through research in the protection of warships by demagnetization against magnetic mines, he received numerous distinctions:
Events from the year 1904 in France.1970 in science
The year 1970 in science and technology involved some significant events, listed below.2000 in France
The following lists events that happened during 2000 in France.
The year 2000 is in particular remembered in France by a media campaign on the conditions of detention of prisoners. A parliamentary board of inquiry was created. The conclusions of the report were that French prisons were both unhealthy and over-populated. The sanitary arrangements were considered to be scandalous. The government of Lionel Jospin launched a programme to renovate and build new prisons.Abraham Moles
Abraham Moles (1920 – 22 May 1992) was an engineer of electrical engineering and acoustics, and a doctor of physics and philosophy. He was one of the first researchers to establish and analyze links between aesthetics and information theory.
He taught sociology and psychology at the Universities of Ulm, Strasbourg, San Diego, Mexico, Compiègne, and founded the
Institute of Social Psychology of Communication in Strasbourg.
Abraham Moles followed technology studies (electricity and acoustics) at the University of Grenoble (France), as well as he was preparing a bachelor in sciences of nature.
He was first appointed as assistant professor at the Laboratory of metal physics, under the direction of Félix Esclangon, then of Louis Néel. He learned there techniques of metal work, then electric and electronic tools. He wrote reports on testing materials and anaysis.
At the end of the Second World War, he was hired by the French Research Institute CNRS, more precisely at the Laboratory of acoustics and vibrations, in Marseille, and at the CRSIM (Centre de recherche scientifique industriel et maritime), which was the continuation of the French National Marine Laboratory.
He also followed the philosophy courses of Aimé Forest and Jacques Chevalier at the University of Grenoble,then the courses of Gaston Berger at the University of Aix, and the courses of Gaston Bachelard at the Sorbonne.
In 1952, he defended a PhD on La structure physique du signal musical et phonétique (under the direction of René Lucas, Edmond Bauer, Henri Pieron and the physiologist Alexandre Monnier).
He participated to the works of the Centre d’études de la radio-télévision (Jean Tardieu, dir.), and, in particular, was a member of the team around Pierre Schaeffer.
But lacking money, he accepted two grants of the Rockefeller Foundation, in order to work at Columbia University (Music Department headed by Vladimir Ussachevsky).
In 1954, he defended a second PhD, in philosophy, under the title "La création scientifique", under the direction of Bachelard.
From 1954 to 1960, with many interruptions, Abraham Moles was the director of the Laboratoire d’électroacoustique Scherchen, in the small village of Gravesano, in Switzerland, under the direction of Hermann Scherchen, one of the pionneers of Radio Berlin, who had discovered composers as famous as Luciano Berio, Iannis Xenakis, Bruno Maderna, Luigi Nono.
At the same time, Abraham Moles was teaching at the University of Stuttgart (with Max Bense), of Bonn, of Berlin and of Utrecht. He was finally appointed full professorship at the Hochschule für Gestaltung, in Ulm.
After 1966, he taught in Strasbourg (in the department created by Henri Lefebvre), first in sociology, then in the professorship of social psychology. He created there an Institute for social psychology of communications, usually called École de Strasbourg, by former students now members of the Association internationale de micropsychologie et de psychologie sociale des communications. His book Art et ordinateur (1971) transposed for aesthetics the theories of Shannon.
He was also the president of the Société française de cybernétique, founded by Louis Couffignal.Antiferromagnetism
In materials that exhibit antiferromagnetism, the magnetic moments of atoms or molecules, usually
related to the spins of electrons, align in a regular pattern with neighboring spins (on different sublattices) pointing in opposite directions. This is, like ferromagnetism and ferrimagnetism, a manifestation of ordered magnetism.
Generally, antiferromagnetic order may exist at sufficiently low temperatures, but vanishes at and above the Néel temperature – named after Louis Néel, who had first identified this type of magnetic ordering. Above the Néel temperature, the material is typically paramagnetic.CNRS Gold medal
The CNRS Gold medal is the highest scientific research award in France. It is presented annually by the French National Centre for Scientific Research (CNRS) and was first awarded in 1954. Moreover, Silver Medals are given to researchers for originality, quality, and importance, while Bronze Medals recognize initial fruitful results.Institut Néel
Institut Néel is a research laboratory in condensed matter physics located on Polygone Scientifique in Grenoble, France. It is named after scientist Louis Néel.
The institute is an independent research unit (UPR2940) of the French Centre national de la recherche scientifique created in 2007 as a reorganization of four research laboratories: the center for research in very low temperatures (Centre de Recherches sur les très basses températures (CRTBT)), the laboratory for the study of electronic properties of solids (laboratoire d’étude des propriétés électroniques des solides (LEPES)), the Louis Néel laboratory (laboratoire Louis Néel (LLN)), and the Laboratory of crystallography (Laboratoire de cristallographie (LdC)).Louis Néel Medal
The Louis Néel Medal has been awarded annually since 1994 by the European Geophysical Society (EGS), usually for magnetism, palaeomagnetism and petrophysics, and is named after the Nobel Laureate Louis Néel, known for his research in the field of magnetism. It is awarded for outstanding contributions in the application of experimental and theoretical methods of solid state physics to the study of earth sciences.Lycée du Parc
The Lycée du Parc is a public secondary school located in the sixth arrondissement of Lyon, France. Its name comes from the Parc de la Tête d'Or, one of Europe's largest urban parks, which is situated nearby.
It provides a lycée-level education and also offers classes préparatoires, or prépas, preparing students for entrance to the elite Grandes Écoles such as Ecole Polytechnique, Centrale Paris, ESSEC Business school or HEC Paris.
The school was built on the cite of the former Lunette des Charpennes, part of the Ceintures de Lyon system of fortifications built in the 19th century.Magnon
A magnon is a quasiparticle, a collective excitation of the electrons' spin structure in a crystal lattice. In the equivalent wave picture of quantum mechanics, a magnon can be viewed as a quantized spin wave. Magnons carry a fixed amount of energy and lattice momentum, and are spin-1, indicating they obey boson behavior.Michel Soutif
Michel Soutif (8 July 1921 – 28 June 2016), Officier de la Légion d’honneur, Grand Officier de l’ordre national du Mérite, Chevalier de l'Ordre National du Mali, was a French scientist and educator, known for his major contribution to the development of the University of Grenoble in the years following the Second World War. He is also known for his early work on nuclear magnetic resonance, centimetre wavelength radiation (microwaves) and electron spin resonance. He graduated from the Ecole Normale Supérieure (ENS), and, on completing his thesis, was invited by Louis Néel to a post at the University of Grenoble, where he established the Laboratoire de Spectrométrie Physique. Both men, Néel and Soutif, understood the importance of the relationship between industry and fundamental research, and of the consequent need to attract new industries to the surrounding region. Soutif’s success in obtaining teaching posts and in reinforcing the discipline of physics at the University of Grenoble was remarkable. He is recognized not only for his scientific achievements but also for the outstanding clarity of his teaching and his mission to spread scientific reason.
These were talents that, in the positions of responsibility and decision that he occupied during his career, propelled him to become one of the principal architects of the growth of the University.Neel
Neel may refer to:
Alice Neel (documentary) film about painter Alice Neel
Neel, in Indian numbering system
Neel Kamal (1947 film) directed by Kidar Nath Sharma
Neel Trimarans, a multihull sailboat company founded and managed by Eric Bruneel and based in La Rochelle, FranceNéel effect
In superparamagnetism (a form of magnetism), the Néel effect appears when a superparamagnetic material in a conducting coil is subject to varying frequencies of magnetic fields. The non-linearity of the superparamagnetic material acts as a frequency mixer, with voltage measured at the coil terminals. It consists of several frequency components, at the initial frequency and at the frequencies of certain linear combinations. The frequency shift of the field to be measured allows for detection of a direct current field with a standard coil.Néel relaxation theory
Néel relaxation theory is a theory developed by Louis Néel in 1949 to explain time-dependent magnetic phenomena known as magnetic viscosity. It is also called Néel-Arrhenius theory, after the Arrhenius equation, and Néel-Brown theory after a more rigorous derivation by William Fuller Brown, Jr. Néel used his theory to develop a model of thermoremanent magnetization in single-domain ferromagnetic minerals that explained how these minerals could reliably record the geomagnetic field. He also modeled frequency-dependent susceptibility and alternating field demagnetization.Pierre Weiss
Pierre-Ernest Weiss (25 March 1865, Mulhouse – 24 October 1940, Lyon) was a French physicist specialized in magnetism. He developed the domain theory of ferromagnetism in 1907. Weiss domains and the Weiss magneton are named after him. Weiss also developed the molecular or mean field theory, which is often called Weiss-mean-field theory, that lead to the discovery of the Curie-Weiss law. Alongside Auguste Picard, Pierre Weiss is considered one of the first discoverers of the magnetocaloric effect in 1917.Pierre Weiss made several experimental discoveries that led to the development of the strongest electromagnets of the beginning of the 20th century. He worked at the universities of Rennes, Lyon, ETH Zurich where he was raised, and finally at Strasbourg. In these academic institutions he founded several renown laboratories.Polygone Scientifique
The Polygone Scientifique (en: Scientific Polygon) is a neighborhood of the city of Grenoble in France. It includes a significant number of research centers in a presque-isle between Isère and Drac.Rayleigh law
The Rayleigh law describes the behavior of ferromagnetic materials at low fields.
Ferromagnetic materials consist of magnetic domains. When a small external field is applied, domains parallel to the external field start to grow. In this region, domain walls are moving. They are hindered by material defects. Lord Rayleigh investigated this first and quantified the magnetization as a linear and quadratic term in the field:
Here is the initial susceptibility, describing the reversible part of magnetisation reversal. The Rayleigh constant describes the irreversible Barkhausen jumps.
The Rayleigh law was derived theoretically by Louis Néel.,
The same law describes polarization and direct and converse piezoelectric response of some ferroelectric and ferroelectric-ferroelastic materials. The common feature for ferromagnetic, ferroelectric and ferroelastic materials (i.e., ferroic materials) are domains whose boundaries (domain walls) can be moved by magnetic, electric or mechanical fields.Superparamagnetism
Superparamagnetism is a form of magnetism which appears in small ferromagnetic or ferrimagnetic nanoparticles. In sufficiently small nanoparticles, magnetization can randomly flip direction under the influence of temperature. The typical time between two flips is called the Néel relaxation time. In the absence of an external magnetic field, when the time used to measure the magnetization of the nanoparticles is much longer than the Néel relaxation time, their magnetization appears to be in average zero; they are said to be in the superparamagnetic state. In this state, an external magnetic field is able to magnetize the nanoparticles, similarly to a paramagnet. However, their magnetic susceptibility is much larger than that of paramagnets.
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