How Does Heat Affect Magnets?

Magnetic materials should maintain a balance between temperature and magnetic domains (the tendency of atoms to rotate in a particular direction). However, this equilibrium state becomes unstable when exposed to extreme temperature, and magnetic properties are affected. Magnets are strengthened with cold, but heat causes loss of magnetic properties. In other words, too much heat will completely destroy the magnet.

Overheating moves atoms more quickly, which can disturb magnetic domains. As atoms accelerate, the proportion of magnetic domains rotating in the same direction decreases. This lack of cohesion weakens the magnetic force and eventually completely demagnetizes it.

Conversely, when the magnet is exposed to extreme cold, the atom will decelerate, so the magnetic domains align and strengthen the magnetic field.

Certain materials form a way to strongly interact with permanent magnets or magnets. Most everyday magnets are ferromagnetic

A magnet that appears only when there is an external magnetic field. They are attracted to the magnetic field, but they are not magnetized even if the external magnetic field is removed. This is due to the fact that the atoms are rotating in a random direction, the spins are not aligned, and the total magnetization is zero.

Named after French physicist Pierre Curie, the Curie temperature is the temperature at which the domain does not exist. Because atoms are too crazy to maintain aligned rotation. At this temperature, the ferromagnetic material becomes paramagnetic. Even if you cool the magnet, once it is demagnetized it will no longer be magnetized. The Curie temperature will be different if the magnetic material is different, but the average temperature is 600 ~ 800 ℃

In order to understand the temperature effect, it is necessary to investigate the atomic structure of the elements making up the magnet. By strengthening or weakening the attractive force of the magnet, the temperature affects the magnetic force. As the particles in the magnet move faster and at a more scattered rate, the heated magnet decreases its magnetic field. This confusion causes the magnetic domains to be disordered, causes misalignment, and degrades magnetic properties. Conversely, if the same magnet is exposed to low temperature its magnetic properties will increase and its strength will increase.

Like a strong external magnetic field, the temperature can cause the magnetic domain of the magnet to lose its direction. When the permanent magnet is heated, atoms in the magnet vibrate. The more the magnet is heated, the greater the atomic vibration becomes. At some point, the atomic oscillation changes from an ordered pattern in which domains are aligned to a disordered pattern that is not aligned. The temperature at which overheating vibrates atoms and rearranges the magnet regions is called the "Curie point" or "Curie temperature".

An important part of the relationship between the magnet and the temperature is that as you heat the magnet the molecules become more disordered. Magnet is a dipole. That is, opposite ends have opposite charge or magnetic orientation. This is because most magnetic molecules are oriented in the same direction. As the magnets are heated, their polar molecules begin to move. The average direction of the polarity of the whole magnet is a little troublesome because these magnetic molecules are not facing in the same direction.