The magnetism of materials originates from the magnetic moments of electrons in atoms. Matter is composed of atoms, which in turn are made up of a nucleus and electrons. Within an atom, electrons have orbital magnetic moments due to their motion around the nucleus; electrons also possess spin magnetic moments because of their spin. The magnetic moment of an atom primarily originates from the electron magnetic moments, which is the source of magnetism in all matter.

The magnetic moment is a vector with a direction. The spin of electrons in an atom can be either up or down. In most substances, the number of electrons with upward spin is equal to the number with downward spin, and the magnetic moments they produce cancel each other out, resulting in no magnetic properties for the entire atom. Only in a few substances do the atoms have an unequal number of electrons with different spin directions. After the magnetic moments of electrons with opposite spins cancel each other out, there remains a portion of the electrons' spin magnetic moments that are not canceled, giving the entire atom a net magnetic moment. The magnetic moment of a single atom depends on its atomic structure, and all elements in the periodic table have their own magnetic moments.

Due to the different magnetic moments of various atoms, there is an interaction between the atomic magnetic moments in macroscopic materials, leading to different arrangements of atomic magnetic moments at room temperature. Based on the differences in magnetic intensity and magnetic susceptibility of macroscopic materials in an external magnetic field, they are classified as paramagnetic substances, diamagnetic substances, ferromagnetic substances, ferrimagnetic substances, and antiferromagnetic substances.

Magnetic Moment and Magnetic Flux: Conversion can be made through coil constants.

The magnetic moment (magnetic moment) and magnetic flux (magnetic field) are both important parameters describing the strength of the magnetic properties of permanent magnetic materials, and there is a certain correlation between them, but they are physical quantities of different meanings.

The commonly used test method for magnetic moment is carried out according to the standard IEC60404-14 of the International Electrotechnical Commission (testing the magnetic dipole moment of ferromagnetic materials by pulling or rotating method). The measurement of magnetic moment is actually calculated by measuring the open-circuit magnetic flux. Measuring the open sample in a one-dimensional Helmholtz coil with a strictly calibrated coil constant k can obtain the magnetic flux value Ø, and the magnetic moment M of the material can be calculated through the magnetic flux value.

The calculation formula is as follows:

M = k * Ф

M represents the magnetic moment of the magnet, with the unit of Wb cm^-1

k represents the coil constant, with the unit: cm^-1 (changes in the unit of the coil constant will cause changes in the unit of magnetic moment)

Ф represents the magnetic flux value, with the unit: Wb

The magnetic flux value measured for the same magnet under different coil constants is different, but the calculated magnetic moment is the same. Therefore, communicating the magnetic moment between buyers and sellers is more accurate and efficient.