Dual nature of the 5f electrons in plutonium materials

Abstract

The electronic structure of select Pu materials is examined by means of photoemission (PES) and model calculations. We present the first photoemission results and electronic structure calculations for the material PuIn 3. Results for Pu materials, including the cubic delta-phase metal and the superconductor PuCoGa 5, give indication of the 5f electrons exhibiting both localized and itinerant character. These new results for PuIn 3 place this compounds also in the 5f dual nature category. The dual nature of the Pu 5f electrons demarks the boundary between localized and itinerant 5f character in the actinides.The photoemission data for δ -Pu, PuIn 3 and PuCoGa 5 are compared against model calculations. The calculations are a mixed level model (MLM) which is a multi-electron extension of the generalized gradient approximation. Using the MLM, one obtains good agreement for the volume and total energy minimum with 4 of 5 Pu 5f electrons localized. The calculations also agree well with the PES spectra. Other computational schemes and interpretations are also reviewed.