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 PrOs4Sb12 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 Γ1 with triplet Γ4 first excited state, where the quadrupolar interaction plays essential role for the AFQ ordering.