Visionneuse

Date_TXT

New York: KLUWER ACADEMIC PUBLISHERS, 2004

Auteur

K. H. J. Buschow, F. R. de Boer

Sujet

Magnétisme; Grecs anciens; Magnesia; Magnétite; Magnétisation; Champ magnétique; Courant électrique; Électromagnétisme; Oersted; Sturgeon; Gauss; Maxwell; Faraday; Curie; Weiss; Magnétisation spontanée; Température; Domaines magnétiques; Bloch; Landau; Néel; Matériaux magnétiques; Technologie moderne; Dispositifs électromécaniques; Dispositifs électroniques

Type de document

Livre

Description :

The first accounts of magnetism date back to the ancient Greeks who also gave magnetism its name. It derives from Magnesia, a Greek town and province in Asia Minor, the etymological origin of the word “magnet” meaning “the stone from Magnesia.” This stone consisted of magnetite and it was known that a piece of iron would become magnetized when
rubbed with it.
More serious efforts to use the power hidden in magnetic materials were made only much later. For instance, in the 18th century smaller pieces of magnetic materials were combined into a larger magnet body that was found to have quite a substantial lifting power.
Progress in magnetism was made after Oersted discovered in 1820 that a magnetic field could be generated with an electric current. Sturgeon successfully used this knowledge to produce the first electromagnet in 1825. Although many famous scientists tackled the phenomenon of magnetism from the theoretical side (Gauss, Maxwell, and Faraday) it is mainly 20th century physicists who must take the credit for giving a proper description of magnetic materials and for laying the foundations of modem technology. Curie and Weiss succeeded in clarifying the phenomenon of spontaneous magnetization and its temperature dependence. The existence of magnetic domains was postulated by Weiss to explain how a material could be magnetized and nevertheless have a net magnetization of zero. The properties of the walls of such magnetic domains were studied in detail by Bloch, Landau, and Néel.