The wiki comments: en.wikipedia.org/w/index.php?title=Ferromagnetism&oldid=965600553#Explanation
The Bohr-van Leeuwen theorem, discovered in the 1910s, showed that classical physics theories are unable to account for any form of magnetism, including ferromagnetism. Magnetism is now regarded as a purely quantum mechanical effect. Ferromagnetism arises due to two effects from quantum mechanics: spin and the Pauli exclusion principle.
Ferromagnetism is a fundamental magnetic property of certain materials, primarily metals, characterized by a strong attraction to magnetic fields and the ability to retain magnetization even after the external magnetic field is removed. This behavior is due to the alignment of magnetic moments of atomic or molecular dipoles within the material.
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