A proton has spin and magnetic moment just like an electron. Why then its effect is neglected in magnetism of materials?
Spins of proton and electron are equal. But the magnetic momentsare inversely proportional to themass of the particle. Proton is about 2000 times heavier than the electron so proton's magnetic moment is smaller by three orders of magnitude. Thus its effect is negligible in comparison toelectron magnetic moment.
