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What happens to a ferromagnetic material at its Curie temperature?

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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.

When a ferromagnetic material is heated to its Curie point—also known as the Curie temperature—it undergoes a sharp change in its magnetic properties, losing its characteristic ferromagnetism.12

At temperatures below the Curie point, the material's constituent atoms, which act as tiny magnets, spontaneously align in the same direction within microscopic regions called domains, causing their magnetic fields to reinforce one another. As the material reaches the Curie temperature, the thermal energy becomes sufficient to disrupt these internal aligning forces. Consequently, the spontaneous magnetization vanishes, and the material transitions into a state of paramagnetism, where it exhibits only weak magnetic behavior.12

This process is reversible; if the material is cooled back below its Curie point, the magnetic atoms spontaneously realign, and its ferromagnetism is restored.12