Grain Diameter and Coercivity of Fe, Ni, and Co Metals

The relationship between coercivity and grain diameter was investigated for pure Fe, Ni and Co metals. The grain diameter of samples was varied between 200Å and 5 ¿m by preparing sputtered films and rapidly quenched ribbons. The coercivity in all cases was roughly proportional to the sixth power of the grain diameter below a certain diameter (200Å, 400Å and 300Å for Fe, Ni and Co respectively), and was proportional to the reciprocal of the grain diameter at larger values. This behavior can be satisfactorily explained in terms of the random anisotropy model proposed by Herzer and Alben et al.