Neutron scattering study on the field-induced antiferro-quadrupolar ordering in the heavy fermion superconductor PrOs4Sb12

Abstract We found the field-induced antiferro-quadrupole (AFQ) ordering in the Pr-based heavy fermion superconductor PrOs 4 Sb 12 by means of neutron scattering. The field-induced staggered moment and the field dependence of the crystal field excitation spectra can be well understood in terms of the mean field Hamiltonian based on the singlet Γ 1 with triplet Γ 4 first excited state, where the quadrupolar interaction plays essential role for the AFQ ordering.