diamagnetism (redirected from diamagnetic)

diamagnetism: see magnetism.

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diamagnetism

Kind of magnetism characteristic of materials that line up at right angles to a nonuniform magnetic field and that partly expel from their interior the magnetic field in which they are placed. In most materials, the magnetic fields of the electrons balance each other and add up to zero. However, when placed in an external magnetic field, the interaction of this field with the electrons induces an internal field in the opposite direction. The substance can then be weakly repelled by magnetic poles. Examples of diamagnetic substances include bismuth, antimony, sodium chloride, gold, and mercury.

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diamagnetism

the phenomenon exhibited by substances that have a relative permeability less than unity and a negative susceptibility. It is caused by the orbital motion of electrons in the atoms of the material and is unaffected by temperature

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Diamagnetism

That branch of magnetism which treats of diamagnetic phenomena and of the properties of diamagnetic bodies. Diamagnetism is a property exhibited by substances with a negative magnetic susceptibility, that is, by substances which magnetize in a direction opposite to that of an applied magnetic field. A diamagnetic substance has a magnetic permeability less than 1, and is repelled when placed near a magnet. The magnetization of diamagnetic substances is associated with the currents induced on application of a magnetic field. See Magnetic susceptibility

Although all matter exhibits diamagnetism, only those substances in which paramagnetism is absent are referred to as diamagnetic. This is because paramagnetism, if present, usually predominates, and the gross magnetic response of the material is paramagnetic. Important exceptions are the alkali and alkaline earth metals. The condition for pure diamagnetism is that all electronic spins be paired and all orbital moments either be zero or effectively cancel one another. See Paramagnetism

As stated previously, the diamagnetic response of a substance is small; only a very small fraction of the applied magnetic field is shielded from the interior of the substance by the induced diamagnetic currents. There is one case, however, in which the inducing field is completely shielded (except for small surface effects). This is the perfect diamagnetism exhibited by superconductors, and is known as the Meissner effect. See Meissner effect, Superconductivity