Evidence for antiferromagnetic-type ordering of f-Eelectron multipoles in PrIr2Zn20

Neutron diffraction measurements conducted under applied magnetic fields evidence the ordered structure of PrIr2Zn20 below approximately 0.1 K. A two-channel (orbital) Kondo effect is expected to act within the non-Kramers doublet ground state of the Pr 4f electrons of this material in cubic symmetry. Antiferromagnetic reflections are clearly induced under the influence of applied magnetic fields, which are characterized by the propagation vector q = (1/ 2,1/ 2,1/ 2). This result indicates antiferromagnetic-type ordering of the Pr f-electron multipoles. The Gamma(3)-type quadrupole, O-2(2), is the dominant order parameter deduced from the observed magnetic structure factor. We also discuss the entanglement of various finite-magnitude multipoles up to third rank, which are relevant to the low-energy crystalline-electric-field split levels in this material.