What is the Curie temperature of magnets?

The Curie temperature is known as the temperature at which the ferromagnetic element starts to lose its magnetism and becomes paramagnetic when this temperature is exceeded. In the case that the material is below the Curie temperature, magnetic materials are transformed into ferromagnetic ones. This temperature comes from Curie's law: it states that the susceptibility (the ability of a material to be magnetized by an external magnetic field) of a magnetic material is inversely proportional to the temperature.

As we can see in the graph, when a ferromagnetic element exceeds the Curie temperature, it becomes a paramagnetic element.

The person who determined the Curie temperature was the Frenchman in 1895 who discovered the laws that relate the alterations found in magnetic elements to the temperature at which they are found.

How can temperature affect the magnets?

The temperature at which is found in magnetic materials that have the presence of an external field, which contains ferromagnetic properties.

From the point of view of rocks and minerals, the ability of the element to maintain magnetism is at 570ºC; an example of minerals would be magnetite.

Low temperatures: If a magnet is at low temperatures the magnetism of the magnet will increase. When materials are in an environment with low temperatures, the magnetic atoms spontaneously realign themselves achieving a revival of ferromagnetism, antiferromagnetism, or ferromagnetism. In the case of minerals, the ability to retain magnetism is below the Curie point.

High temperatures:If the magnet is at high temperatures the magnetism of the magnet will be affected by the strength it possesses. This increase in temperature leads to conversion from ferromagnetism to paramagnetism, creating an increase in temperature, which is known as the Curie temperature.

What are the Curie temperatures of different materials?

Depending on the different types of magnets we will find different temperatures:

Material Curie Temperature
AlNiCo700 - 850°C
SmCo700 - 800°C

To know the loss or decrease of the magnetic properties of a material, when it reaches the Curie temperature, we will need the Curie Pendulum. This pendulum has a metal tip that is attracted to the magnet due to magnetic forces. On the other hand, to operate the pendulum we will need a candle, which will be the element that provides the heat.

The pendulum works as follows: when the element is heated by the candle and its temperature has increased, it will lose its magnetic properties, so it will move away. When the element is no longer attracted by the heat source, it will cool down, recover its properties, and will be attracted to the magnet again.

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