Studies on magnetic and electronic properties of δ-PuX₃ (X = Al, Ga, In, and Tl) compounds

The magnetic properties of δ-PuX₃ (X = Al, Ga, In, and Tl) are investigated using first-principles calculations. Non-zero magnetism is found in Pu atoms, resulting from the sum of the spin magnetic moment and orbital magnetic moment which is opposite to the former. The origin of the orbital moment is revealed by the occupation of f orbitals with different magnetic quantum numbers, which also accounts for the larger magnetization in PuAl₃ compared to those in other PuX₃ compounds. Moreover, the stable magnetic orderings are explored, showing that the in-plane antiferromagnetic arrangement with the axial ferromagnetic arrangement is the most favorable magnetic configuration for all the four compounds. Besides, the decomposed electronic band structures with p, d, and f projections as well as the phonon dispersions for the PuX₃ compounds are also present.