Unified character of correlation effects in unconventional Pu-based superconductors and delta-Pu

[摘要] Electronic structure calculations combining the local-density approximation with an exact diagonalization of the Anderson impurity model show an intermediate 5 f(5)-5 f(6)-valence ground state and delocalization of the 5 f(5) multiplet of the Pu atom 5f shell in PuCoIn5, PuCoGa5, and delta-Pu. The 5f local magnetic moment is compensated by a moment formed in the surrounding cloud of conduction electrons. For PuCoGa5 and delta-Pu the compensation is complete, and the Anderson impurity ground state is a singlet. For PuCoIn5 the compensation is partial, and the Pu ground state is magnetic. We suggest that the unconventional d-wave superconductivity is likely mediated by the 5 f-state antiferromagnetic fluctuations in PuCoIn5 and by valence fluctuations in PuCoGa5.

[关键词] ELECTRONIC-STRUCTURE;PLUTONIUM;VALENCE;PUCOGA5;TRANSITION;SYSTEMS;STATES