The effect of structural disorder upon the magnetic properties of nanocrystalline material was studied; especially with regard to the  = 3 and  = 5 special grain boundaries, and the extreme case of a purely amorphous sample. The configurations were minimized by using molecular dynamics simulations and embedded-atom potentials. Electronic structure calculations were performed by using the tight-binding linear muffin-tin orbital atomic-sphere approximation. The calculations revealed that the magnetic moment was relatively insensitive to the degree of disorder that was present in the structure, and varied by at most 20% at the special grain boundaries. The results could be correlated extremely well with recent data, on electroplated Ni, which showed that the magnetic moment depended very little upon grain sizes of down to about 10nm. That is, it was not critically dependent upon the amount of matter in the grain boundaries. Even in the limit where all of the volume belonged to interfaces (amorphous material), the average magnetic moment was reduced by only about 15%. The local moments in amorphous material varied between 0.4 and 0.6B, and a weak correlation was observed between the magnitude of the local moment and the average nearest-neighbor distance.

B.Szpunar, U.Erb, G.Palumbo, K.T.Aust, L.J.Lewis: Physical Review B, 1996, 53[9], 5547-56