Write the type of magnetism observed when the magnetic moment are aligned in parallel and anti-parallel directions in unequal numbers?

(i) Ferrimagnetism: This effect is observed when the magnetic moments of the domains in the substance are aligned in parallel and anti-parallel directions in unequal numbers. (ii) Vacancy Defects: When some lattice sites are left vacant during the formation of a crystal, the defect is called a vacancy defect. In vacancy defects, an atom is missing from its regular atomic site. Because of the missing atom, the density of the substance decreases, i.e., because of vacancy defects.