Some phenomena in Nature only appear if many particles act together, these are *emergent* effects. One typical example for such an effect is magnetism. Whether a material is magnetic or not is intimately related to the effective [[Spin|spin]] of the atoms involved in the material. A single spin does not create a magnet, but their interactions can lead to a strong enough effect that materials like iron or chrome are magnetic. Here, a large number of spins align in one direction and create a net-magnetic effect. This type of magnetism is called ferromagnetism. >[!read]- Further Reading >- [[Spin]] >[!ref]- References