Is the paramagnetic transition of magnetic material reversible?
Theoretically, the transition from ferromagnetic to paramagnetic is a reversible process, and there is no doubt about it. After cooling down, it naturally turns from paramagnetic to ferromagnetic.
If it is a single crystal or large size, reach the Curie temperature is no problem, but for the nano level, very easy to be oxidized, five hundred degrees Celsius can be transformed into gamma iron oxide Fe3O4, after cooling is not your original material.
But for some substances, such as Fe3O4, there is a problem of stability.
