Why diamagnetism can't occur in classical mechanics?
Where can I know more about that?
But it does! Any application of Lenz's law where a magnetic moment tries to oppose change in an applied field is essentially the classical equivalent of diamagnetism.
What about the Bohr-van Leeuwen theorem?
Doesn't it states that there is no diamagnetism in classic mechanics?
Bohr-van Leeuwen is a theorem ruling out magnetic ordering in classical mechanics. However, diamagnetism is a response to a magnetic field, not a type of magnetic ordering, so all is well.
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