Inelastic neutron scattering measurements in a quadrupolar ordering compound YbSb

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 Γ₆ - Γ₈ excitations far above the quadrupolar ordering temperature (T_Q). This result suggests that the magnetic excitations have a dispersion rather than the splitting of Γ₈ 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.