Kondo universality and energy scales in plutonium

The macroscopic properties of α and δ-plutonium were analyzed within the Fermi-liquid approach аs well as the properties of a few model rare earth-based systems. The following major parameters in Pu were estimated within the single-site approximation: the characteristic Kondo energy, the f-electron shell occupation number, the effective degeneracy of the ground f-multiplet, the crystal field splitting energy. The ground state in δ-plutonium is a quantum superposition of two atomic states Pu³⁺ and Pu²⁺. According to its macroscopic physical properties δ-Pu at low temperature is very close to the intermediate valence regime. The temperature dependence of the static magnetic susceptibility in plutonium was calculated. Since the universal Wilson criterion and the Kadowaki-Woods universal relation are valid in δ-Pu it can be considered as a Kondo system, while the position of α-plutonium in the general classification of solids remains a puzzle. The plutonium homology issue is discussed.