Can permanent magnet loss its magnetism or be demagnetized?

Well, according to Wikipedia, YES! To quote;

Permanent magnets can be demagnetized in the following ways:

- Heating a magnet past its Curie point* will destroy the long range ordering.
- Contact through stroking one magnet with another in random fashion will demagnetize the magnet being stroked, in some cases; some materials have a very high coercive field and cannot be demagnetized with other permanent magnets.
- Hammering or jarring will destroy the long range ordering within the magnet.
- A magnet being placed in a solenoid which has an alternating current being passed through it will have its long range ordering disrupted, in much the same way that direct current can cause ordering.

* The Curie point of a ferromagnetic material is the temperature above which it loses its characteristic ferromagnetic ability (768°C for iron). At temperatures below the Curie point the magnetic moments are partially aligned within magnetic domains in ferromagnetic materials. As the temperature is increased towards the Curie point, the alignment (magnetization) within each domain decreases. Above the Curie point, the material is purely paramagnetic and there are no magnetized domains of aligned moments.

The Curie Point of naturally occurring permanent magnets or lodestone is 535 deg C where as the Currie Point of Iron is 768 deg C.

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