J. Phys. Soc. Jpn. 75S (2006) pp. 209-214  |Previous Article| |Next Article|  |Table of Contents|
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Proc. of 5th Int. Symposium on ASR-WYP-2005 – Advances in the Physics and Chemistry of Actinide Compounds –

Hybridization and Multipole Orders of 4f Electrons in Pr Skutterudites

Yoshio Kuramoto, Annamária Kiss, Junya Otsuki and Hiroaki Kusunose

Characteristics of hybridization and multipole orders of 4f-electrons in Pr skutterudites are explained in terms of a pseudo-quartet composed of crystalline electric field (CEF) singlet and the triplet. It is shown that the contrasting behaviors observed in PrFe₄P₁₂ and PrOs₄Sb₁₂ are ascribed to the difference in triplet wave functions and the CEF splittings. Since a macroscopic degeneracy remains even in the ordered phase with the Γ₃-type antiferro-quadrupole (AFQ) order, a model with strong AFQ fluctuation and static monopole/hexadecapole order is proposed for PrFe₄P₁₂. The remaining cubic symmetry explains qualitatively the behavior of staggered magnetization observed by NMR and neutron scattering. For identification of possible hexadecapole orders in PrFe₄P₁₂ and PrRu₄P₁₂, eightfold intensity pattern is predicted in the azimuthal angle scan of resonant X-ray scattering. In PrOs₄Sb₁₂, the ferromagnetic exchange coupling with the conduction band does not lead to magnetic Kondo effect, but a momentum-dependent quadrupole coupling can give rise to enhanced effective mass, which should be sensitive to disorder.

URL: http://jpsj.ipap.jp/link?JPSJS/75S/209/
DOI: 10.1143/JPSJS.75S.209
KEYWORDS:quadrupole order, quantum fluctuation, resonant X-ray scattering, skutterudite

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