A permanent magnet is a magnet that is permanent, in similarity to an electromagnet, which only acts like a magnet when an electric current is streaming through it. Permanent magnets are prepared of substances like magnetite , the most magnetic arising mineral, or neodymium, a powerfully magnetic synthetic substance. The Earth itself is a enormous permanent magnet, though its magnetic field is relatively weak relative to its size. Humans have utilized the magnetic field of the Earth for navigation since, the compass was designed in ancient China.
Soft magnetic materials are those materials that are simply magnetized and demagnetized. The classes of applications for soft magnetic materials fall into two main categories: AC and DC. For DC applications the foremost consideration for material selection is most likely to be the penetrability. This would be the case, for example, in shielding applications where the flux must be directed through the material. Where the material is used to produce a magnetic field or to create a force then the saturation magnetization may also be significant. For AC applications the significant consideration is how much energy is lost in the system as the material is cycled around its hysteresis loop.
- Intermetallic and other Hard Magnetic Materials
- Rare-earth transition metal borides
- Carbon-based magnetic materials
- Crystalline, nanocrystalline and amorphous materials
- Nanostructured Hard Magnetic Materials
- Applications of Hard and Soft Magnetic Materials