Anisotropy and temperature dependence of the spin-wave stiffness in Nd2Fe14B: An inelastic neutron scattering investigation

The anisotropy and the temperature dependence of the spin-wave stiffness constants of the permanent magnet Nd2Fe14B are determined in the range 160-440 K using single-crystal inelastic neutron scattering technique. It is found that the deviation from isotropic spin-wave dispersion, between the a and the c axis of the tetragonal structure, is small and eventually the anisotropy decreases when the temperature increases. The softening of the stiffness constants can be described by a linear temperature variation with an average rate of about -0.46 meV angstrom(2)/K. These results are compared with the most recent atomistic and multiscale calculations.