Thermomagnetism refers to the temperature change when a magnetic substance is magnetized by an external magnetic field under adiabatic conditions. However, when applied to ferromagnetic materials in a narrow sense, magnetocaloric effect refers to the temperature change accompanied by the change of magnetic domain structure when magnetized in a weak magnetic field or a medium magnetic field, while magnetocaloric effect refers to the temperature change accompanied by the forced increase of spontaneous magnetization when the magnetic field is strengthened.

Magnetization increases the number of parallel superparamagnets (such as spins) in magnets. As a result, the exchange energy and static magnetic energy in the external magnetic field are reduced. Because the magnetization is carried out under adiabatic conditions, the reduced energy will be converted into heat energy of the variable magnet. These heat energies in turn increase the temperature of the whole magnet through the coupling between the super magnet and the lattice (such as spin lattice or orbital lattice).