(What Im basically trying to understand is what causes magnetism, but this is a specific bit of that discussion)
In all discussions of this topic I hear about magnetic moment of electrons due to them orbiting the proton and due to their spin.
But some places they say, orbital moments always cancel out, and only spin causes net magnetic moment.
Other places they say, both contribute to magnetic moment and some even say that its all orbital moment, and spin moment is negligible.
So, I need a definitive answer.
Which of the two causes the magnetic moment in matter?
If both do, then in what circumstances is one of them negligible and other one rules?