Néeln.
/ˈneɪəl/, U.S. /ˈneɪəl/ Physics.
1. Néel spike n. (also Néel domain) a sharply pointed triangular magnetic domain associated with a small hole or inclusion in a magnetic substance (the hole or inclusion typically being surrounded by a number of such domains).
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the world > matter > physics > electromagnetic radiation > magnetism > [noun] > magnetic field > domain
Néel spike1949
1949 Rev. Mod. Physics 21 572/2 Measurement of the ratio of length to width of the Néel domains offers a possible experimental method for determining..the surface energy density of a Bloch wall.
1951 Jrnl. de Physique et le Radium 12 311 (caption) Néel ‘spikes’ around holes in a crystal surface.
1964 Science 16 Oct. 399/2 Point C in Fig. 2 indicates a radial arrangement of tiny closure domains (known as Néel domains) surrounding a hole.
1996 A. Aharoni Introd. Theory of Ferromagnetism ix. 207 A particularly nice example [of theoretical interpretation of data] is the shape of the so-called Néel spikes, which are formed..near non-magnetic inclusions.
2. Néel temperature n. (also Néel point) the transition temperature for an antiferromagnetic or ferrimagnetic substance, above which it is paramagnetic (analogous to the Curie temperature for ferromagnetics).
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the world > matter > physics > electromagnetic radiation > magnetism > types of magnetism > [noun] > point of temperature change
Néel temperature1952
1952 Physica 18 714 In warming the salt through the region of the Néel temperature a continuous but rapid change occurs from a state in which the spins of the Cu++ ions are highly ordered to a state of comparative disorder.
1953 Proc. Royal Soc. A. 217 258 Temperature curves of the solid solutions in the region of the Néel points of the parent substances.
1984 N. N. Greenwood & A. Earnshaw Chem. of Elements (1986) xxiv. 1220 If the temperature is reduced below about 118K (its Neél point), a rapid fall in magnetic moment takes place as the electron spins on adjacent Mn atoms pair-up.
1990 New Scientist 23 June 53/1 Above a certain critical temperature—called the Curie temperature (TC) for ferromagnets, and the Néel temperature (TN) for antiferromagnets—the thermal energies overcome spin interactions and the material becomes paramagnetic.
3. Néel wall n. a domain boundary in a thin layer of magnetic material across which the spin directions change orientation in the plane of the layer.
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the world > matter > physics > electromagnetic radiation > magnetism > [noun] > magnetic field > domain > feature of
powder pattern1934
Néel wall1960
1960 Jrnl. Appl. Physics 31 (Suppl.) 303S/1 The smooth parts of the wall at the thin and thick ends of the film have to be interpreted as pure Néel and Bloch walls, respectively.
1966 R. Carey & E. D. Isaac Magn. Domains ii. 24 Néel walls become energetically more favourable than Bloch walls for thin films.
1989 Nature 16 Feb. 637/1 Because Néel walls do not generate large normal field gradients, even quite complex structures..might not be imaged by the Bitter technique.
This entry has been updated (OED Third Edition, September 2003; most recently modified version published online March 2022).
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