Britannica Sources used in this answer

Why do temporary magnets lose their magnetism when the magnetizing field is removed?

Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

Diagram showing a circular loop of wire with an electric current, surrounded by curved blue lines representing magnetic field lines that loop around the wire and pass through its center. — magnetism Some lines of the magnetic field B (blue) for an electric current I (gold) in a loop.

Temporary magnets lose their magnetism when the magnetizing field is removed because their internal magnetic domains are able to return to their original, random orientations.

In ferromagnetic materials, magnetization occurs when an external field causes small regions called domains to align with that field. In materials that act as temporary magnets, this alignment is easily reversible. When the external magnetizing field is removed, the domain walls—which moved to align with the field—are able to return to their original positions, resulting in little to no remanent magnetization.123

This behavior is characteristic of "soft" magnetic materials, which have a "thin" hysteresis loop, indicating that they are easily magnetized and demagnetized with minimal energy loss. In contrast, permanent magnets are typically made of "hard" materials with structural imperfections or specific compositions that "lock" domain walls in place, preventing them from returning to their random state once the external field is withdrawn.241