Neutron Brillouin scattering with pulsed spallation neutron source -   spin-wave excitations from ferromagnetic powder samples -
  Neutron Brillouin scattering (NBS) method was developed using a pulsed spallation neutron source, and the feasibility of NBS was demonstrated by observing ferromagnetic spin waves in La$_{0.8}$Sr$_{0.2}$MnO$_3$ and SrRuO$_3$ powders. Gapless spin-wave excitations were observed in La$_{0.8}$Sr$_{0.2}$MnO$_3$, which were continuously extended to the lower scattering vector $Q$ from previous results using single crystals. The novel result is a well-defined quadratic $Q$ dependence in the spin-wave dispersion curve with a large energy gap in SrRuO$_3$ indicating robust spin-orbit coupling. 
S. Itoh, Y. Endoh, T. Yokoo, D. Kawana, Y. Kaneko, Y.Tokura, M. Fujita
cond-mat.str-el