Multipoles in -Pu

Hotta, Takashi

In order to develop microscopic theories of magnetism and superconductivity in -electron compounds, we have proposed the construction of an -electron model on the basis of a - coupling scheme. Using this model, we have explained spin and orbital structure of UMGa and NpMGa. Recently, octupole ordering in NpO has been also understood from the microscopic viewpoint. Encouraged by such successes of the j-j coupling model in actinide materials, we attempt to understand magnetism and superconductivity of Pu and PuMGa. We focus on a key role of 5f orbital state for the appearance of superconductivity in PuMGa and the absence of magnetism in -Pu. We discuss multipoles as spin-orbital complex degrees of freedom.