Question

What happens to a ferromagnetic material when the external field is removed ?

Answer 1

When the external magnetic field is removed, magnetisation disappears in some of the materials like soft iron. Those materials are called soft ferromagnets.
However, in materials like Alnico ( an alloy of iron, aluminium, nickel, cobalt and copper), the magnetisation persists even after removal of external magnetic field. Such materials are called hard ferromagnets.