Introduction to paramagnetism
Paramagnetism refers to the weak magnetic response of materials to magnetic fields. For example, the magnetic susceptibility k = M / H (M and H are the magnetization and magnetic field strength, respectively). From this relationship, the magnetic susceptibility k is positive, that is, the direction of the magnetization is the same as the magnetic field strength, and the value is 10 －6-10-10 order of magnitude.
Some atomic nuclei (such as 1H, 7Li, 11B, 13C, 17O, etc. and neutrons) have magnetic moments, which will produce paramagnetism under the action of a magnetic field, but their paramagnetic susceptibility is much smaller than the contribution of electrons to paramagnetic, only 10 －6-10-10 order of magnitude. Therefore, when discussing the paramagnetic properties of matter, the paramagnetic properties of the core can be ignored.