magnetic susceptibility

magnetic susceptibility [mag′ned·ik sə‚sep·tə′bil·əd·ē]

(electromagnetism)

The ratio of the magnetization of a material to the magnetic field strength; it is a tensor when these two quantities are not parallel; otherwise it is a simple number. Also known as susceptibility.

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Magnetic susceptibility

The magnetization of a material per unit applied field. It describes the magnetic response of a substance to an applied magnetic field. See Magnetism, Magnetization

All ferromagnetic materials exhibit paramagnetic behavior above their ferromagnetic Curie points. The general behavior of the susceptibility of ferromagnetic materials at temperatures well above the ferromagnetic Curie temperature follows the Curie-Weiss law. The paramagnetic Curie temperature is usually slightly greater than the temperature of transition. See Curie temperature, Curie-Weiss law, Ferromagnetism

Most paramagnetic substances at room temperature have a static susceptibility which follows a Langevin-Debye law. Saturation of the paramagnetic susceptibility occurs when a further increase of the applied magnetic field fails to increase the magnetization, because practically all the magnetic dipoles are already oriented parallel to the field. See Paramagnetism

The susceptibility of diamagnetic materials is negative, since a diamagnetic substance is magnetized in a direction opposite to that of the applied magnetic field. The diamagnetic susceptibility is independent of temperature. Diamagnetic susceptibility depends upon the distribution of electronic charge in an atom and upon the energy levels. See Diamagnetism

The susceptibility of antiferromagnetic materials above the Néel point, which marks the transition from antiferromagnetic to paramagnetic behavior, follows a Curie-Weiss law with a negative paramagnetic Curie temperature.