NEUTRON SCATTERING INVESTIGATIONS ON FeMnNi(Be) ALLOYS

摘要

The diffraction data show that the investigated Be -containing Fe Mn Niγ-alloys consist of the disordered f.c.c. v -phase and toe Ni Be -phase, where the con¬centration of the latter depends on the annealing tempe¬rature and the degree of cold-working. Inelastic scattering experiments show that the Be atoms in the γ -phase causes the localized modes with excitation energy 46 meV, while the pbonon cut-off-energy 36 meV. Peaks at energies higher than and are interpreted as excitations due to acoustic and optical anhferromag-nons. This can be explained with the help of the modified Zener model in which the two magnon branches are caused by two inequivaient subsystems: the localized moments of Ni and the itinerant electrons of Fe and Mn .nThe authors would like to express their thanks to Or. B.Lippoid for experimental assistance and Dr. Yu.M.Ostanevich for stimulating discussions.