Antiferro-polarization of octupolar moment in phase III of CeB6 - Analysisof NMR spectra

Anomalous NMR spectra in phases III and III' of CeB6 are analyzed theoretic ally Ly introducing a new type of hyperfine coupling of the B-11 nuclei wit h Ce multipolar moments. It is shown that the observed spectra can be repro duced if we take into account the antiferro-polarization of the T-xyz octup ole in addition to the antiferromagnetic order proposed by neutron diffract ion experiment (ND). Thus ND and NMR are mutually consistent in phase III, if the octupolar contribution is properly included. The analysis of NMR giv es the magnitude of the polarization of the octupolar moment. The present a nalysis strongly suggests that the antiferro-quadrupolar ordering of Gamma( 5)(+) type is playing an important role behind the mysterious 2k antiferrom agnetic ordering of phase III.