The magnetism of matter comes from the magnetic moment of electrons in atoms
Matter is made up of atoms, which are made up of nuclei and electrons. In atoms, electrons have orbital magnetic moments because they move around the nucleus; electrons have spin magnetic moments due to spin. The magnetic moment of atoms mainly comes from the electron magnetic moment, which is the source of the magnetism of all materials.
The magnetic moment is a directional vector. The spin modes of electrons in atoms are divided into two types: up and down. In most materials, there are as many electrons with upward spin as there are downward spin. The magnetic moments they generate cancel each other out, and the entire atom has no external magnetism. Only a few matter atoms have different numbers of electrons in different spin directions. In this way, after the magnetic moments of electrons with opposite spins cancel each other out, the spin magnetic moments of the remaining electrons have not been canceled out, and the entire atom has a total magnetic moment. The magnetic moment of a single atom depends on the atomic structure, and atoms of all elements in the periodic table have their own magnetic moments.
Due to the different magnetic moments of different atoms, the interaction of atomic magnetic moments between macroscopic substances leads to different arrangements of atomic magnetic moments at room temperature. According to the differences in magnetization intensity and magnetic susceptibility of macroscopic substances in an external magnetic field, they are divided into paramagnetic substances, diamagnetic substances, ferromagnetic substances, ferrimagnetic substances, and antiferromagnetic substances.
Magnetic moment and magnetic flux: can be converted by coil constant
Magnetic moment and magnetic field are both important parameters that describe the magnetic strength of permanent magnet materials. There is a certain correlation between them, but they are physical quantities with different meanings.
The commonly used test method for the magnetic moment is carried out according to the International Electrotechnical Commission standard IEC60404-14 (pull or rotation method to test the magnetic dipole moment of ferromagnetic materials). The measurement of magnetic moment is calculated by measuring the open circuit magnetic flux. By measuring the open-circuit sample in a one-dimensional Helmholtz coil with a strictly calibrated coil constant of k, the magnetic flux value Ø can be obtained, and the magnetic moment M of the material can be calculated from the magnetic flux value. Calculated as follows:
M = k * ФM
Represents the magnetic moment of the magnet, the unit is Wb·cm-1k represents the coil constant, unit: cm-1 (the unit change of the coil constant will cause the change of the magnetic moment unit)
Ф represents the magnetic flux value, unit: Wb
For the same magnet, the magnetic flux values measured under different coil constants are different, but the calculated magnetic moment is the same. Therefore, the magnetic moment communication between buyers and sellers will be more accurate and efficient.