Inelastic neutron scattering measurements in a quadrupolar ordering compound YbSb

Abstract Inelastic neutron scattering measurements were performed to study the excitation spectra of a quadrupolar ordering compound YbSb. We observed the three peaks (12.5, 17 and 21 meV) around Γ 6 – Γ 8 excitations far above the quadrupolar ordering temperature ( T Q ). This result suggests that the magnetic excitations have a dispersion rather than the splitting of Γ 8 states at high temperatures. We also observed the strong q dependence in q scans at energy = 1 meV above T Q . The observed q dependence above T Q suggests that the theoretical approach beyond the molecular field approximation is required in order to understand the magnetic properties of Yb monopnictides.