Microscopic theory of multipole ordering in NpO2
Abstract
In order to examine the mysterious ordered phase of NpO2 from a microscopic viewpoint, we investigate an f -electron model on an fcc lattice constructed based on a j-j coupling scheme. First, an effective model with multipole interactions is derived in the strong-coupling limit. Numerical analysis of the model clearly indicates that the interactions for Γ4u and Γ5u moments are relevant to the ground state. Then, by applying a mean-field theory to the simplified model including only such interactions, we conclude that the longitudinal triple- q Γ5u octupole order is realized in NpO2 through the combined effects of multipole interactions and anisotropy of the Γ5u moment.
- Publication:
-
Physical Review B
- Pub Date:
- April 2005
- DOI:
- 10.1103/PhysRevB.71.140404
- arXiv:
- arXiv:cond-mat/0409116
- Bibcode:
- 2005PhRvB..71n0404K
- Keywords:
-
- 75.30.Et;
- 75.40.Cx;
- 71.10.Fd;
- Exchange and superexchange interactions;
- Static properties;
- Lattice fermion models;
- Condensed Matter - Strongly Correlated Electrons
- E-Print:
- 5 pages, 2 figures