What is Remanence?

Ever wondered why a magnet stays magnetized long after it’s removed from a magnetic field? That’s remanence at work.

Remanence, or residual magnetization (Br), is the level of magnetism a permanent magnet retains after the external magnetic field is removed.

35SH BH curve

Let’s dive deeper into this essential property of permanent magnets and how it relates to coercivity.

what is remanence(Br)?

Magnets don’t just “forget” their magnetism. Remanence shows how much magnetism remains in a material.

Remanence (Br) is measured in Tesla or Gauss and indicates the strength of magnetism retained when the magnet is no longer exposed to an external magnetic field.

magnetic hysteresis curve

The science of remanence

Remanence (Br) reflects how strongly a permanent magnet holds onto its magnetic properties after magnetizing. The magnet’s material composition, structure, and domain alignment determine its remanence.

1. Why Br Matters

Br is critical for applications that need a stable magnetic field without ongoing power. For example, in motors or generators, higher remanence means more consistent performance.

2. How Br is Measured

Br is measured by magnetizing the sample to saturation, removing the external field, and recording the remaining magnetization.

3. Material Considerations

Materials like Neodymium-Iron-Boron (NdFeB) offer high Br values, making them ideal for applications requiring strong, lasting magnetism. SmCo magnets also have high Br but with better temperature stability. On the other hand, Ferrite magnets have lower Br but are inexpensive and corrosion-resistant.

In my business, I’ve seen customers switch from Ferrite to NdFeB magnets for high-performance devices like drones and EVs because they need high Br for efficiency and compact design.

Conclusion

Remanence tells us how well a permanent magnet retains its magnetism after magnetizing. It’s key for choosing the right magnet for any application.