Question

What happens to a ferromagnetic material when its temperature is raised above Curie temperature?

Hint:

The Curie temperature marks the transition point where ferromagnetic materials lose their magnetic properties and become paramagnetic due to thermal agitation.

Answer 1

When a ferromagnetic material is heated above its Curie temperature, it undergoes a phase transition and loses its ferromagnetic properties. The Curie temperature is the critical temperature at which the thermal energy becomes sufficient to overcome the alignment of the magnetic dipoles in the material, causing it to become paramagnetic.
Ferromagnetic State:
Below the Curie temperature, the magnetic moments (spins) of the atoms in the material align in the same direction due to the interaction between neighboring atomic spins. This alignment results in a net magnetization, and the material exhibits strong magnetic properties. These materials can retain their magnetization even after the external magnetic field is removed. The interactions between the spins are stronger than the random thermal motions, allowing the material to stay magnetized.
Above Curie Temperature:
When the material is heated beyond the Curie temperature, the thermal energy of the system increases. This increase in thermal energy causes the atomic spins to become randomly oriented due to the random motion of the atoms, disrupting the alignment of the magnetic moments. As a result, the material loses its ferromagnetic properties and behaves like a paramagnet. In the paramagnetic state, the material will still be weakly magnetized in the presence of an external magnetic field, but this magnetization is not permanent. Once the external field is removed, the material no longer retains its magnetization. This transition from ferromagnetism to paramagnetism is due to the dominance of thermal energy over the magnetic interaction between atoms at temperatures higher than the Curie point. Thus, above the Curie temperature, the ferromagnetic material loses its magnetic properties and becomes paramagnetic.