Curie temperature

The temperature above which a ferromagnetic material loses spontaneous magnetic order. Above it, thermal agitation prevents long-range alignment of its magnetic moments.

Ferromagnetism: A form of magnetism in which neighboring magnetic moments align spontaneously, producing a net magnetization. Curie temperature marks the loss of this ordered magnetic state.
Magnetic moment: A vector measure of the strength and orientation of a source of magnetism. Collective alignment of these moments produces ferromagnetic order.
Magnetic recording: The storage of information by encoding it in the magnetization of a material. Heating near a material’s Curie temperature can erase or reset recorded magnetization.
Néel temperature: The temperature above which an antiferromagnet loses long-range magnetic order. It is the corresponding ordering threshold for antiferromagnets, not ferromagnets.
Iron: A chemical element and ferromagnetic metal with a Curie temperature near 770 °C. Its familiar transition illustrates that ferromagnets become paramagnetic when heated sufficiently.
Exchange interaction: A quantum-mechanical interaction between particle spins that favors particular relative alignments. It drives the alignment that thermal agitation overcomes above the Curie temperature.
Magnetic domain: A region in a magnetic material where magnetic moments share a common orientation. Domains organize the material’s magnetization below its Curie temperature.
Heat-assisted magnetic recording: A data-storage method that briefly heats a recording medium to make its magnetization easier to switch. Its laser heating exploits the reduced magnetic stability near the Curie temperature.
Blocking temperature: The temperature above which a nanoparticle’s magnetization fluctuates rapidly enough to lose stable time-averaged orientation. Unlike a Curie temperature, it reflects particle size and measurement timescale.
Nickel: A chemical element and ferromagnetic metal with a Curie temperature near 358 °C. Its lower threshold makes magnetic order easier to lose than in iron.

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