Inelastic Neutron Scattering Studies on the Amorphous and Nanocrystalline Fe76Cu1Nb3Si14B6

Abstract

Inelastic neutron scattering measurement has been used to study the temperature and wave-vector dependence of the spin wave excitation in the amorphous and nanocrystalline state of ferromagnetic Fe76Cu1Nb3Si14B6 alloy. For the amorphous alloy the spin waves were observed over the accessible wave-vector range of 0.055 Å-1 ≤q ≤0.105 Å-1, for temperature between 300 K (0.49 T c) and 547 K (0.90 T c). The magnon dispersion curves exhibit the conventional quadratic relationship E = D(T)q2 + Δ, typical of an isotropic ferromagnet, where the small energy gap Δ≈0.05 meV is attributed primarily to the dipole-dipole interaction. An estimate of the T = 0 value of D(0) ≈153 meV Å2 was obtained from a plot of D(T) vs T extrapolated to low temperatures, while the Curie temperature of 610 K was obtained from the extrapolation of D(T) to zero at high temperatures. There is the increase of the spin wave stiffness constant D with the transformation of the alloy from amorphous to nanocrystalline state.