Step 1: Understanding the Concept:
Magnetism in solids arises from the alignment of magnetic moments of electrons. Ferromagnetism is the strongest form of magnetism.
Step 3: Detailed Explanation:
In ferromagnetic substances, the individual magnetic moments of atoms (domains) are spontaneously aligned in the same direction even in the absence of an external magnetic field.
When placed in a magnetic field, all these domains get oriented in the direction of the field, resulting in a very strong magnetic effect.
Unlike paramagnetic substances, ferromagnetic materials remain magnetized even after the external magnetic field is removed, making them suitable for permanent magnets.
Common examples include Iron (\(Fe\)), Cobalt (\(Co\)), Nickel (\(Ni\)), and Gadolinium (\(Gd\)).
Step 4: Final Answer:
Ferromagnetism is the characteristic of materials that exhibit spontaneous and permanent magnetization.