system
Given the following post, respond as if you're commenting on Reddit:
human
What keeps magnetic domains in alignment?

In the production of permanent magnets, it is known that heating the metal up and then slowly cooling it down in the presence of a large external magnetic field will align the domains and they will stay in line creating  a permanent magnet. 

What is it that stops the domains from scattering after they are cooled down in the same way that the domains scatter after a normal piece of metal is removed from a magnetic field?
gpt
In these materials you need energy to randomize the magnetization, the aligned state is energetically favorable based on the properties of the atoms and their crystal structure.

You can provide that energy by e.g. heating the material above its Curie temperature, then the material will lose its magnetic field.