Why does the magnet not have magnetism when it is heated?
For all magnetic materials, they are not magnetic at any temperature. Generally, the magnetic material has a critical temperature Tc, the temperature above, due to the intense thermal motion of atoms under high temperature, the electronic arrangement becomes out of order arrangement of the atomic magnetic moment is chaotic, then will disappear into the magnetic magnet magnetic. Below this temperature, the magnetic moment of the atom is arranged in order, producing spontaneous magnetization, and the object becomes ferromagnetic.
The Curie point, also known as the Curie temperature or magnetic transition point, refers to the temperature at which the material can change between the ferromagnet and the magnet, i.e., the phase transition temperature of the ferromagnet from the ferromagnetic phase to the paramagnetic phase. It can also be said that there is a transition temperature of the two phase transition. Below the temperature of the Curie point, the substance becomes ferromagnetic, where the magnetic field associated with the material is difficult to change. When the temperature is higher than the temperature of the Curie point, the material becomes a paramagnetic substance.
In physics there is a specific term for the magnet - Curie temperature, which is the phenomenon.
