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 nf = 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. Motivated by the potential implication for effects of gallium doping on the electronic and bonding properties of delta‐phase plutonium, the electronic properties of Pu3Ga are studied by using a many‐body scheme with the dynamical correlation and spin‐orbit coupling effects. Pu3Ga has antiferromagnetic order and strong valence fluctuation with an average occupation of localized 5f electrons nf = 4.9598. Optimization of lattice parameter, total and spin magnetic moments, and momentum‐resolved electronic spectrum function are also discussed.