ferromagnetic domains.
A domain is a region in which all the atoms are arranged in such a way that their magnetic moments are parallel to each other. within each domain, a special form of interaction called “exchange coupling ” exists among the adjacent atoms rendering all the dipole moments of all atoms within the domain in the same direction to provide a strong resultant magnetic moment associated with each domain. In the absence of magnetic field they cancel out eachother therefore the ferromagnetic material will remain unmagnetised.