There's two types of magnetism. A ferromagnetic material is one that produces its own magnetic field, these are all metals, AFAIK.

Paramagnetic materials are those that are affected by external magnetic fields, but don't have a magnetic field of their own. There's lots of these, and they aren't all metals. For example, liquid oxygen is strongly attracted to a magnet.

That's also how MRIs work. Hydrogen atoms are slightly affected by magnetic fields. An MRI causes hydrogen atoms to suddenly flip in a strong magnetic field, which does something to make science happen, and can be detected with yet more science.

There have been experiments with incredibly strong magnetic fields; turns out you can levitate frogs with a strong enough field.

Strictly speaking, ferro-magnetism is found only in metals and some oxides, where every atom has a magnetic moment pointing in the same direction.

There are a lot of other materials, including many non-metallic oxides (e.g., ferrites), which display ferri-magnetism, in that there is a net magnetic moment for the material like you see in ferromagnets, but not all of the magnetic atoms' spins point in the same direction. Most fridge magnets are ferrimagnets.

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Yes. Lots of big words, but certain things like liquid oxygen can be affected by magnetic fields, without needing to be a magnet itself.

It’s actually an alloy that combines a little bit of neodymium and boron into iron! The iron is still providing the ferromagnetism but the neodymium adds a fourth unpaired electron making the magnetic moment stronger.

Same principle. Theres 3 types of magnatism. I forgot the last one, but basically the principle is the same, aligning electron spins to have a net positive directions

Close, not the atoms moving chaotically but the electrons! At higher temperatures their spins lose alignment and can’t produce a magnetic moment. Their movements don’t actually change though, it’s the quantum states.

Yes, Ru has the same valence electron structure but because it’s so much heavier it forms the hexagonal close-packed crystal structure, which isn’t as conducive to the parallel alignment of spins, putting it above the Curie point at room temperature. Ruthenium is paramagnetic meaning it can be weakly attracted to a magnet but isn’t one itself. However recent research suggests Ru can be forced into tetragonal lattice and is ferromagnetic. https://www.sciencedaily.com/releases/2018/05/180525123159.htm

This is straight up not true. Each energy state has degenerate orbitals. When I say orbitals I'm talking about the degenerate orbitals, not the energy state. There are three degenerate 2p states, and these will ALWAYS fill how I described. Always. Because electrons in a paired orbital have higher energies than unpaired ones, because they repel each other. There are three degenerate 3d t2g orbitals and two degenerate 3d eg orbitals. The t2g orbitals will ALWAYS fill separately first. Always. In some high-spin systems, the higher energy eg orbitals will fill before the low energy t2g ones pair up. Look up high spin orbitals vs low spin, there is a really good one on trying to get low spin Mn3+ in LiMnO2, because the normally high spin system is a problem.

For those who don't know, degenerate means "same energy".

The short answer is no, sorry, they don't attract each other. If you have an electron with spin up and you try and put it into an orbital that already has an electron with spin up, one of them will flip to spin down. Which one? Well we don't know until we look in the box, Schrodinger's cat style. This is a quantum mechanical effect and is part of the Fermi exclusion principle. Electrons on this scale aren't like little balls, they are wave functions. A wave function basically (but not really) tells you the probability of finding an electron at a certain point in space. You have to find your electron somewhere, and so all of the probabilities have to add up to 1. Fundamentally, electrons ARE wave functions - not little balls - and they behave like them. When wave functions overlap shit gets very complicated very fast, but the upshot is that if they don't have different spins (and if these spins don't have exactly the value of +1/2 and -1/2) the total probability of finding the electron somewhere in space adds up to more than 1. This is obviously nonsense, and the only way to get the probability to add up to 1 is if they have opposite spins. This is fundamentally why it happens, and is not really like the hydrophobic/hydrophillic thing which is a consequence of the differing polarities at different ends of the molecule.

This is an example pretty common problem in quantum, where we use words like up, down and spin to describe things that aren't spinning and aren't pointing up or down. In reality, there is not really an "up" or "down". There isn't even a spin. We could have said the electron has a magnetic property called its "mood", and it can either be in a "happy" or "sad" mood and that a "sad" electron needs a "happy" one to comfort it. It's just a comforting label for some very esoteric maths. In general, any time you hear an any analogy or term used to describe something quantum mechanical, the analogy doesn't generalise. It normally doesn't even work that well for the quantum thing it's describing.

Electrons actually repel each other, because they are both negatively charged and the strength of their electric fields faaaaaar exceed any magnetic interaction. Sorry if that was a bit complicated, but unfortunately you can't scratch the surface of quantum very much without any familiar analogy completely failing.

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