Observation of Modulated Quadrupolar Structures in PrPb_3

摘要

Neutron diffraction measurements have been performed on the cubic compound PrPb_3 in a [001] magnetic field to examine the quadrupolar ordering. Antiferromagnetic components with q = (1/2 ± δ 1/2 0), (1/2 1/2 ± δ 0) {8 ≈ 1/8) are observed below the transition temperature T_Q (0.4 K at H = 0) whose amplitudes vary linear with H and vanish at zero field, providing the first evidence for a modulated quadrupolar phase. For H < 1 T, a nonsquare modulated state persists even below 100 mK suggesting quadrupole moments associated with a Γ_3 doublet ground state to be partially quenched by hybridization with conduction electrons.