Single crystal neutron inelastic scattering measurement of stiffness constant in disordered f.c.c. Ni-Mn alloys

Inelastic neutron scattering measurement of stiffness constant D on simple crystals of disordered f.c.c. Ni-Mn alloys has been performed at differen Mn concentrations (1.5%, 6%, 12%, 18% at.Mn). Stiffness constant D show similar behaviour vs concentration as observed in Ni-Fe alloys by Hennion et al. Solid State Commun.17, 899 (1975)]. This behaviour does not agree with that observed by inelastic small-angle magnetic scattering measurements by Menshikov et al. Int. J. Magn.1, 91 (1975)]. A noticeable enhancement of the spin-wave width is also observed at higher Mn content and higher spin wave energies. The values of pair exchange integrals are also given.