Quadrupolar and magnetic ordering in CeB₆

The quadrupolar ordering in CeB₆ is explained in terms of the electrostatic interaction of quadrupolar moments arranged into a simple cubic lattice. The representation of magnetic and quadrupolar moments by means of quasispins of two kinds is employed. A linear increase of the quadrupolar transition temperature T_Q(H) with applied magnetic field and its further reentrance are described using a generalized spherical model which is well adjusted to a particular problem of the quadrupolar ordering in CeB₆. The theory naturally explains the growing specific heat jump at T_Q(H) with increasing magnetic field. The role of the quadrupolar ordering in the formation of the magnetic ordering, as well as the possible critical experiments and applications to other rare-earth compounds, are discussed.