Magnetic excitations in ferromagnetic phase of MnP

Abstract 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.