T. Sakakibara et al., Interplay of orbital and magnetic degrees of freedom in f-electron systems: The cases of PrPb3 and TmTe, J PHYS JPN, 69, 2000, pp. 25-32
Effect of magnetic field on the antiferro-quadrupolar (AFQ) phase in the cu
bic compounds PrPb3 and TmTe has been studied by means of magnetization and
specific heat measurements. In PrPb3, it is found that the AFQ transition
temperature T-Q (=0.4 K at H=0) remarkably increases in magnetic field. Thi
s behavior is well explained by antiferromagnetic interactions between the
field-induced staggered magnetic moment in the AFQ phase. Analysis of the o
bserved anisotropy T-Q([100])(H) > T-Q([110])(H), however, strongly suggest
s the presence of a weak ferro-octupolar interaction. In TmTe, magnetic sus
ceptibility chi(T) increases enormously on cooling and appears to diverge u
pon an antiferromagnetic (AF) transition at T-N=0.22 K. The results imply t
hat a ferromagnetic moment is induced in the AF phase by an alternating ani
sotropy due to the preexisting AFQ order at T(Q)approximate to 1.8 K. This
is possible when both AF and AFQ states are described by the same wave vect
or, in agreement with recent neutron diffraction studies.