Stability of charge and magnetic orderings due to competing interactions in PrFe _4P _(12)

摘要

The origin of a mysterious phase transition at 6.5 K in the skutterudite PrFe_4P_(12) has long been a subject of intensive research.1) Recent microscopic experiments such as NMR, X-ray, and neutron scattering commonly showed that the local symmetry around each Pr site is unbroken below the transition temperature, although the two neighboring Pr sites become inequivalent.2-4) It means that the symmetry of the order, parameter belongs to a class of nonmagnetic charge. These experimental facts remind oneself of a similarity with unconventional charge ordering (CO) in PrRu_4P_(12).