Magnetic excitations in ferromagnetic phase of MnP

Inelastic neutron scattering experiments were performed on an intermetallic compound, MnP. We used a newly developed High Resolution Chopper Spectrometer, HRC, for energy transfers E <= 75 meV, besides various triple axis spectrometers; LTAS for energy transfers E <= 2 meV, TOPAN for E <= 7.5 meV and TAS-1 for E <= 35 meV. Spin wave excitations were observed in the ferromagnetic phase of MnP in the entire Brillouin zone along the a*- and b*-axes. The zone boundary energies of spin waves were determined to be around 60 meV along the a*-axis and around 75 meV along the b*-axis, and the dispersion relations showed two branches for both axes. The observed dispersion relations of spin waves were well described by an isotropic Heisenberg interaction adding a single ion anisotropy with two sub-lattices. (c) 2013 Published by Elsevier B.V.