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.