Abstract
By evaluating multipole susceptibility of a seven-orbital impurity Anderson model with the use of a numerical renormalization group method, we discuss possible multipole states of actinide dioxides at low temperatures. In particular, here we point out a possible scenario for multipole ordering in americium dioxide. For ion with five electrons, it is considered that the ground state is doublet and the first-excited state is quartet, but we remark that the ground state is easily converted due to the competition between spin-orbit coupling and Coulomb interactions. Then, we find that the quartet can be the ground state of even for the same crystalline electric-field potential. In the case of quartet ground state, the numerical results suggest that high-order multipoles such as quadrupole and octupole can be relevant to .
- Received 1 June 2009
DOI:https://doi.org/10.1103/PhysRevB.80.024408
©2009 American Physical Society