paramagnetism
/ PAR-uh-mag-net-iz-um /
Picture a room full of tiny compass needles, each free to swing, but all being jostled constantly by a rowdy crowd. With no magnet nearby they point in random directions and average to nothing. Switch on a magnetic field and they begin, faintly, to favor lining up with it — a gentle, willing attraction. That mild cooperation is paramagnetism.
It happens in materials whose atoms each carry a leftover magnetic moment that does not cancel. Left alone, heat keeps these moments tumbling randomly. An applied field tugs them toward alignment, but thermal jostling keeps fighting back, so only a small fraction line up at any instant — the material is weakly drawn into the field. Crucially, the colder it gets, the less the jostling, and the stronger the alignment becomes.
Paramagnetism matters as the stepping stone between 'no moments at all' and full-blown magnets: the same atomic needles, if they could only agree among themselves, would make a permanent magnet. The common confusion is to think paramagnets are 'magnetic.' They are not in any useful sense — remove the field and the alignment instantly vanishes, leaving nothing behind.
Liquid oxygen, poured between the poles of a strong magnet, clings to them and bridges the gap like a pale blue puddle held up by an invisible hand. Oxygen molecules each carry a magnetic moment, so the cold liquid is paramagnetic and gets pulled into the field.
Liquid oxygen is paramagnetic — visibly attracted to a magnet, unlike most liquids.
Paramagnetism (attracted to a field) and diamagnetism (pushed away) coexist in the same atom; you see paramagnetism only when the leftover moment is large enough to outweigh the ever-present diamagnetic background.