Magnetic order and valence fluctuation in a Pu-Ga intermetallic compound studied via a first principles calculation

In order to reveal electronic properties of a plutonium-gallium intermetallic compound (Pu3Ga), and its potential implication for microscopic mechanisms for effects of Ga doping on the electronic and structural properties, as well as the phase stability of delta-phase Pu-Ga alloy, a first principles calculation on the magnetic properties of this system is implemented by using density functional theory (DFT) plus on-site Coulomb repulsion U with nonmagnetic, ferromagnetic, and antiferromagnetic (AFM) orders, while the intermediate correlation effect, which is beyond the scope of pure itinerant and localized electronic model, is investigated by using a many-body technique combining DFT and dynamical mean-field theory considering the dynamical correlation effect due to the incompletely filled Pu 5f orbitals and the relativistic effect by inclusion of spin-orbit coupling (SOC). Our findings show that Pu3Ga is a bad metal with AFM order, which is in good agreement with the experimental magnetic measurement. SOC further splitting Pu 5f states into j = 5/2 and j = 7/2 manifolds, the former exhibits metallic character, while the latter insulating feature. Occupation analysis establishes that an average occupancy of Pu 5f electrons in Pu3Ga is n(f) = 4.9598, this result together with the spectrum function indicates that 5f electrons in this system might be a localized state with strong valence fluctuation. Additionally, optimization of lattice parameter, density of state, and momentum-resolved electronic spectrum function are also presented.