Anisotropy of the Neutron Scattering in the Paramagnetic Phase and on the Spin Waves in the Mn0.71Ni0.29 Alloy

We have confirmed the significant anisotropy of the generalised magnetic susceptibility in the paramagnetic and antiferromagnetic phase of the fcc Mn–Ni alloys. In this paper the detailed account of the experiments performed on the Mn0.71Ni0.29 alloy is given. Our main result for the paramagnetic phase is that the correlation length is larger for the direction parallel to the anisotropy axis than for the perpendicular one by a factor of 1.6. The spin-wave velocity observed at 15 K is higher for the direction parallel to the anisotropy axis than that for the perpendicular direction by a factor of 1.2. These results are similar to that for the Mn0.62Ni0.38 alloy. Our results indicate that the magnetic carriers are more localized and the magnetic interactions are less extended in alloys with higher Ni concentration. PACS numbers: 61.05.fm, 78.70.Nx, 75.30.Ds, 75.40.–s, 75.40.Gb 1