Permanent magnet

A permanent magnet produces a persistent magnetic field without an external electric current or applied magnetic field. Its magnetization remains after the field that created it is removed.

Magnetic domain: A region in a magnetic material where many atomic magnetic moments align in the same direction. Permanent magnets retain a net field when many domains remain aligned.
Ferromagnetism: A form of magnetic order in which atomic moments align spontaneously, producing a net magnetization. Most strong permanent magnets rely on ferromagnetic order.
Electric motor: A device that converts electrical energy into mechanical motion through electromagnetic forces. Permanent magnets provide a steady field in many motor designs.
Electromagnet: A magnet whose magnetic field is produced by electric current, usually in a coil. Unlike a permanent magnet, its field can be controlled by changing the current.
Neodymium magnet: A strong permanent magnet made primarily from a neodymium–iron–boron alloy. It combines high magnetic strength with broad use in compact devices.
Magnetization: The magnetic dipole moment per unit volume of a material. A permanent magnet’s field arises from its persistent magnetization.
Exchange interaction: A quantum-mechanical interaction that favors particular relative orientations of neighboring magnetic moments. It drives the collective alignment underlying ferromagnetism.
Loudspeaker: A transducer that converts an electrical audio signal into sound by moving a diaphragm. Its permanent magnet supplies the field that drives the voice coil.
Solenoid: A coil of wire that produces a magnetic field when electric current flows through it. It creates magnetism through current rather than retained material magnetization.
Samarium–cobalt magnet: A high-performance permanent magnet made from samarium and cobalt alloys. It retains useful magnetic properties at higher temperatures than many alternatives.

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