Neutron brillouin scattering with pulsed spallation neutron source - Spin-wave excitations from ferromagnetic powder samples - Spin-wave e

摘要

The neutron Brillouin scattering (NBS) method, which was developed using advanced neutron sources, was extended to an intense pulsed spallation neutron source. The feasibility of this method 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 extrapolated 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.