In the demagnetization curve of the permanent magnetic material, when the reverse magnetic field H increases to a certain 

value bHc, the magnetic induction B of the magnet is 0, and the value of the reverse magnetic field H is the coercive force 

bHc of the material; Magnetic field H = bHc, the magnet does not show outside the magnetic flux, so coercivity bHc 

characterization of permanent magnetic materials against external magnetic field or other demagnetization effect of the ability

The coercivity bHc is one of the important parameters in the magnetic circuit design.

It is worth noting that the coercive force bHc is always smaller in magnitude than the remanence Jr. As can be seen from 

(1-1), at H = bHc, B = 0, then μ0 bHc = J, has been described above, J demagnetization curve at any point of the magnetic

 polarization strength value is always less than remanence Jr , So the coercivity bHc is always smaller than the remanence 

Jr. For example: Jr = 12.3kGs magnets, the bHc can not be greater than 12.3kOe. In other words, the remanence Jr is 

numerically the theoretical limit of the coercivity bHc. When the reverse magnetic field H = bHc, although the magnet's 

magnetic induction B is 0, the magnet does not show outside the magnetic flux, but the magnets within the microscopic 

magnetic dipole moment vector sum is not 0, that is the magnet Magnetic polarization strength J in the original direction 

tends to remain a large value. Therefore, the bHc is not enough to characterize the intrinsic magnetic properties of the 

magnet; when the reverse magnetic field H increases to a value jHc, the magnetic sum of the microscopic magnetic 

dipole moments in the magnet is 0, and the value of the reverse magnetic field H is The intrinsic coercive force jHc of

 the material.

The intrinsic coercive force jHc is a very important physical parameter of the permanent magnetic material. For the magnet 

whose jHc is much larger than bHc, when the reverse magnetic field H is greater than bHc but less than jHc, the magnet has

been demagnetized to the magnetic induction B But after the reverse magnetic field H is canceled, the magnetic induction 

B of the magnet can be returned to the original direction due to the vector sum of the internal microscopic magnetic dipole 

moments in the original direction. That is, as long as the reverse magnetic field H has not reached jHc, the permanent magnet

material has not been completely demagnetized. Thus, the intrinsic coercive force, jHc, is a primary indicator of the ability of

a permanent magnet material to resist an external reverse magnetic field or other demagnetizing effect to maintain its original 

magnetization state.

The units of the coercive force bHc and the intrinsic coercive force jHc are the same as the magnetic field intensity units.