Question

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

Answer 1

Ferromagnetic materials change their magnetic ordering at a characteristic temperature Tc called the Curie temperature.

The Curie temperatures for three common ferromagnetics—iron, cobalt, and nickel—are 1,043 K; 1,394 K; and 631 K, respectively.

For temperatures below the magnetic moments of the ions are aligned and the crystal is magnetic.

For temperatures above Tc the crystal is not ferromagnetic, since the individual atomic moments are no longer aligned.