MODE-COUPLING EFFECTS ON THE QUADRUPOLAR ORDERING IN CEB6

The quadrupolar ordering in CeB6 with unusual dependence on magnetic f ield is explained in terms of mode-coupling effects. A generalized sph erical model with two kinds of quasi-spins is employed for semi-quanti tative argument. The increase of the transition temperature T-Q(H) wit h applied magnetic field is ascribed to suppression of competing quadr upolar lar fluctuations with different wave numbers. The theory natura lly explains the growing anomaly of the specific heat at T-Q(H) with i ncreasing magnetic field.