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A very direct question regarding behaviour of a magnet-

When a magnet is heated such that it melts, why does it lose its magnetism?

This is what I was wondering -

When a solid magnet is heated, the heat is able to provide potential energy to the constituent atoms and thus the magnet turns into molten state. So there is comparitively more inter particle space as compared to the earlier solid state. Moreover, the atoms are now comparitively even more mobile so the alignment of the atoms inside the magnet has been altered as the atoms are not in a fixed position. However some amount of particle movement is also present in solid state.

Please provide a detailed explanation to my intuition if it's right. Otherwise provide me with a suitable explanation for my question.

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Ferromagnetism is a quantum mechanical effect that relies on the ability of atoms to achieve "long range ordering". This ordering results in a coupling of the angular momentum of electrons in neighboring atoms, which leads to magnetic domains. When enough domains align, you get net magnetism.

Heating a material above the Curie temperature destroys this long range ordering - and this can happen below the melting point.

It is possible for a liquid or even a gas to become ferromagnetic - when the conditions are right for this long-range ordering to take place. But most of the time, when the material melts you will lose the order.

Also, for magnetic materials that derive their properties from a particular lattice structure (different types of atoms in a specific arrangement), melting the material will destroy that arrangement.

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  • $\begingroup$ So that means my intuition was partly correct. The alignment which I talked about is actually the North - South magnetic domain alignment. Got it. Thanks $\endgroup$
    – Saksham
    Feb 10, 2017 at 17:30

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