Magnetic excitations in FCC Mn (37%Fe, 3%Cu) alloy

Abstract

PACS 75.20. En, 75.30.Ds, 75.40.Gb Within the program of our systematic studies of magnetic excitations of manganese alloys the inelastic neutron scattering in FCC Mn(37%Fe,3%Cu) was measured for the temperature range 1.7-600 K. This alloy has the FCC crystal structure both in paramagnetic and AF phase and its composition is close to the range where the enhanced itinerant behaviour was predicted by the theory. The measured spin-wave velocity and the energy gap in the spin wave spectrum were reported earlier to reach the maximum values in this composition range. Our data did not confirm these earlier results. The expected anisotropy of the inelastic neutron scattering was not found neither in the antiferromagnetic phase nor in the paramagnetic one. The q-dependence of the spin-wave damping is quadratic rather than linear and the spin-wave damping increase with temperature, as usually predicted for damping due to magnon scattering on magnons and on other excitations. This result is in contrast with the data for the FCT Mn(10%Fe,3%Cu) where the qdependence of the spin-wave damping is linear and the damping parameter was found to be temperature independent excepting the region close to T N .

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

“…No significant anisotropy of the SW scattering was found in any other manganese-rich antiferromagnetic alloys with fcc or tetragonal structure. It was observed neither in fcc Mn-Fe alloys [3,4] nor in Mn 0.863 Ni 0.137 alloy [5]. It was neither mentioned for fcc Mn 0.73 Ni 0.27 [6].…”