Paired Distortion and Anomalies in Kondo Lattice CeB₆

抄録

Long-standing anomalies concerning hidden orderings in Ce_xLa_1-xB₆ competing with the Γ₈ quartet Kondo state are solved by introducing single-site dynamical and pair distorted Jahn-Teller effects. The latter is stronger and enhanced by an increased magnetic field. These characteristic Jahn-Teller effects are common in RB₆ and are related to the soft optical R phonon mode and begin at a temperature corresponding to about half of that of the optical R phonon, causing a long tail of specific heat and a strongly frustrated long-range ordering of paired systems, which is expected to be a [1/2, , 1/2, , 1/2] charge dipolar ordering accompanied by the same magnetic dipole ordering, which is particularly enhanced under a magnetic field. This model clearly explains long-standing anomalies in CeB₆, in particular, the anomalous phase diagram and discrepancies between NMR and neutron scattering measurements.