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 Gamma(6)-Gamma(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 Gamma(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. (c) 2006 Elsevier B.V. All rights reserved.