>Why is a magnetic material magnetic?

1. All electrons have a magnetic moment associated with them, that is just a law of nature that we have to accept..... Even if I had space to detail the math relationship between spin and magnetic moment, ( and I understood it well enough, which I don't), you would still need to accept the notion of magnetic fields as an aspect of nature that currently has no deeper explanation.

2. Some materials, such as iron, allow these electrons to clump in organised domains, rather than randomly, which lets iron's molecular structure act to enhance the magnetic effect, so all these magnetic moments are aligned in the same direction.

3. The domains have to occupy a relatively large volume of the material, depending on their strength.  Aluminum is an example of a metal in which the domains exist but are not as organized or as  widespread as iron.

4. Another example of how important the magnetic domains are, is the fact that almost all magnetic materials are solids, melting a solid will normally disrupt its magnetic field, again iron is special, as the liquid core of the Earth still makes a compass needle move.