Features of the magnetic state of ƒ electrons in the stabilized δ phase of the Pu0.95Ga0.05 alloy

For the Pu_0.95Ga_0.05 alloy belonging to the stabilized δ phase of the Pu-Ga system, the ⁶⁹Ga NMR spectra are measured in the temperature interval 10–650 K and the static magnetic susceptibility χ is measured in the interval T = 20–350 K. In the region T > T* = 235 K, the temperature-dependent magnetic part of the shift K(T) of the Ga NMR line reproduces the χ(T) dependence and follows the Curie-Weiss law K(T) ∼ (T + Θ)⁻¹ with Θ = 280(40) K, which is typical of incoherent spin fluctuations of localized ƒ electrons in concentrated nonmagnetic Kondo systems. The estimate of the effective magnetic moment μ_{eff, 5ƒ} (g _e = 2) = 0.15(5)μ_B per Pu atom testifies to a strong suppression of the spin magnetism in the alloy, where the configuration of the ƒ shell of a Pu ion is close to atomic-like ƒ ⁶. The difference between the K(T) and χ(T) dependences observed for the alloy in the temperature range T < T* is analyzed in terms of the two-fluid description of Kondo lattices developed by Pines et al. [15, 16] in application to the coherent state of a heavy-fermion liquid. Possible causes for the anomalous increase in long-wave contributions in the spatial dispersion of the localized spin susceptibility component of ƒ electrons χ_ƒƒ at temperatures below 50 K are discussed.