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Magnetic classification

- Apr 02, 2018 -

1. Antimagnetic

When the magnetization M is negative, the solid appears diamagnetic. Metals such as Bi, Cu, Ag, and Au have such properties. In an external magnetic field, the magnetic induction inside such a magnetized medium is less than the magnetic induction M in vacuum. The magnetic moment of the atoms (ions) of the diamagnetic material should be zero, ie there is no permanent magnetic moment. When the diamagnetic material is placed in an external magnetic field, the external magnetic field changes the orbit of electrons, induces a magnetic moment opposite to that of the external magnetic field, and manifests itself as diamagnetic. Therefore, diamagnetic resistance originates from the change of orbital states of electrons in atoms. The diamagnetic resistance of a diamagnetic material is generally very weak, and the magnetic susceptibility H is generally about -10^-5, which is a negative value.

2. Paramagnetism

The main characteristic of a paramagnetic material is that there is a permanent magnetic moment within the atom, whether or not an applied magnetic field is present. However, in the absence of an external magnetic field, due to the random thermal vibration of the atoms of the paramagnetic material, macroscopically, there is no magnetism; under the action of an external magnetic field, each atom's magnetic moment is relatively regularly oriented, and the material exhibits very weak magnetic properties. The magnetization is consistent with the direction of the external magnetic field.

It is positive and strictly proportional to the external magnetic field H.

In addition to H, the magnetic properties of paramagnetic materials depend on temperature. Its susceptibility H is inversely proportional to the absolute temperature T.

In the formula, C is called the Curie constant and depends on the magnetization and the magnetic moment of the paramagnetic material.

The magnetic susceptibility of paramagnetic materials is also generally small, and H is about 10^-5 at room temperature. Generally atoms or molecules containing an odd number of electrons, electrons not filling the shell atoms or ions, such as transition elements, rare earth elements, steel elements, and aluminum and platinum metals, are paramagnetic substances.