The Curie point of pure iron is approximately 770 °C, above which iron loses its ferromagnetism.
At temperatures below this point, thermal motion is low enough for many atomic magnetic moments to align into a ferromagnetic order. Heating increases disorder, and at the Curie temperature the long-range alignment disappears. Iron then becomes paramagnetic, meaning it can still respond weakly to an applied magnetic field but is no longer a permanent ferromagnet.
The temperature is named after French physicist Pierre Curie, who studied the relationship between magnetism and temperature. The value applies to pure iron under ordinary conditions; alloys and other magnetic materials have different Curie temperatures. Cooling below the point can restore ferromagnetic ordering.