Dipole-dipole interaction and short-range order in amorphous Ni-P, Ni-Cu-P, and Ni-P-B alloys

The field-independent 31P NMR linewidth, deltaH0, is measured in nonmagnetic amorphous Ni-based alloys. In addition, the second moment contribution M2sup(D) originating from direct nuclear dipole-dipole interaction is calculated using Van Vleck's theory based on a computer generated DRPHS amorphous model cluster. The calculated second moment M2sup(D) and the experimental second moment M2sup(G) obtained from deltaH0 by Gaussian line shape approximation (i.e., M2sup(G) = (deltaH0)2/4) agre fairly well for a (Nisub(0.27)Cusub(0.73))82P18 metallic glass. In the case of amorphous Ni-P and Ni-P-B alloys M2sup(G) exceeds M2sup(D) by a factor of two or three. This excess second moment seems to indicate the presence of some indirect interactions between nuclear spins. (author)