The properties of permanent magnets

In this article, we explore their intrinsic properties—such as induction, remanence, coercivity, and magnetic permeability—which define their performance and longevity.

Magnetic Induction (B)

Magnetic induction refers to the magnetization that occurs in certain materials, known as ferromagnetic materials (iron, cobalt, steel, nickel), when they are placed within a magnetic field, called the inducing field. This magnetization may vanish when the inducing field disappears—such as with soft iron—or it may persist for a longer time, as seen in steel and specific alloys. Magnetization occurs due to the aligned orientation of the microscopic magnets (magnetic domains) within the material, which would otherwise be randomly arranged in the absence of an external field.
Magnetic induction (B) is the key quantity that describes all the properties of a magnetic field.

Magnetic Remanence (Br)

Remanence (Br) measures the magnetic induction or magnetic flux density that remains in a magnet after it has been magnetized.
Put simply: the higher the Br, the stronger the magnet.

Coercivity (Hc)

Coercivity is defined as the intensity of the reverse magnetic field that must be applied to bring a previously saturated material’s magnetization to zero.

Materials with high coercivity are called magnetically hard and are suitable for use as permanent magnets.
Materials with low coercivity are called magnetically soft, and are useful in applications where rapid changes in magnetic field are needed without excessive energy loss—such as in motors and transformers.

Coercive force (Hc) refers to the field intensity needed to completely demagnetize a magnet.
In other words: the higher the coercivity, the better a magnet can resist being demagnetized by an opposing magnetic field.

There are two types of coercivity:

• bHc (based on magnetic flux density)
• jHc (based on magnetic polarization)

If a magnet is exposed to a demagnetizing field of intensity equal to bHc, its flux density disappears. The magnet itself has not lost its magnetization, but the flux it produces is canceled out by the opposing field.

Only when the demagnetizing field equals jHc, will the magnet lose its magnetic polarization, and with it, its magnetization entirely.
Magnetic field intensity is measured in A/m (Amperes per meter)..

Magnetic Permeability (μ)

The magnetic induction B can produce an induced field intensity H in another material, according to a proportionality constant called magnetic permeability (μ), which is characteristic of each substance.

B = μ × H Each material has a specific value of magnetic permeability, allowing materials to be classified based on their μ values.

Technical Support for Permanent Magnets

Our laboratory offers technical support for any inquiries regarding magnetic application design and finite element analysis.

We are equipped with digital fluxmeters, hysteresisgraphs, magnetizers, and more. We can analyze and test your magnets, provide you with complete technical data, and offer cutting-edge solutions aligned with the latest innovations in magnetic material technology.