Which material is a classic example of a ferromagnetic material?

Which material is a classic example of a ferromagnetic material?

• A. Aluminium
• B. Copper
• C. Titanium
• D. Iron

Answer: (D)

Ferromagnetism is the strong, cooperative alignment of magnetic moments in a material, so its atoms form domains where spins point in the same direction and the material can become a permanent magnet. Iron is a classic example because its unpaired electrons in the 3d orbitals interact strongly through exchange forces, causing large regions where the spins align. This ordering persists at room temperature, and iron can be magnetized and retain magnetization to a noticeable degree (though it loses ferromagnetism above its Curie temperature, about 770°C). The other common metals—aluminium, copper, and titanium—do not exhibit this strong, permanent spin alignment at room temperature. Aluminium is only weakly attracted to magnetic fields (paramagnetic), copper is even more weakly affected in the opposite direction (diamagnetic), and titanium is also only weakly paramagnetic.

Ferromagnetism is the strong, cooperative alignment of magnetic moments in a material, so its atoms form domains where spins point in the same direction and the material can become a permanent magnet. Iron is a classic example because its unpaired electrons in the 3d orbitals interact strongly through exchange forces, causing large regions where the spins align. This ordering persists at room temperature, and iron can be magnetized and retain magnetization to a noticeable degree (though it loses ferromagnetism above its Curie temperature, about 770°C). The other common metals—aluminium, copper, and titanium—do not exhibit this strong, permanent spin alignment at room temperature. Aluminium is only weakly attracted to magnetic fields (paramagnetic), copper is even more weakly affected in the opposite direction (diamagnetic), and titanium is also only weakly paramagnetic.