When it comes to the relationship between temperature and magnetism, we must first understand a concept-"Curie temperature".More than 200 years ago, a famous physicist Pierre Curie，discovered a physical characteristic of a magnet in his laboratory, that is, when a magnet is heated to a certain temperature, its original magnetism will disappear. Later, people called this temperature Curie point, also known as Curie temperature Tc or magnetic transition point.

    Curie temperature represents the theoretical working temperature limit of magnetic materials. The Curie temperature is determined by the chemical composition and crystal structure of the material. For example, the Curie temperature of iron is about 770℃ but that of cobalt is about 1131℃.                    

    The maximum working temperature of most magnetic materials is much lower than their Curie temperature. When the working temperature rises, the magnetic force will decrease, but when the temperature does not exceed Curie temperature, the magnetic force will mostly recover. If the temperature exceeds Curie temperature, the internal molecules of the magnet will demagnetize violently, which is irreversible.Although the magnet can be magnetized again after demagnetization, the magnetic force will be greatly reduced, reaching only about 50% of the original.Therefore, it is necessary for us to know the maximum working temperature of magnetic materials to avoid demagnetization caused by high temperature in use.