Abstract
The low-temperature magnetic structure of the AnO2 is critical to the development of high-accuracy computational models. As low-temperature measurements are complicated by thermal energy generated by the radioactive decay of the actinide nuclei, the nature of the magnetic ground state for the AnO2 needs to be calculated by theoretical methods. As such, this is the first systematic study of magnetic order in UO2 and NpO2 considering spin-orbit interactions and noncollinear behaviour.
In this study, the crystal symmetry is coupled by spin-orbit interactions (SOI) to the magnetic state. As a result, we have conclusively linked crystal symmetry linked to transverse 3k AFM order; supporting recent neutron diffraction experiments. By contrast, a transverse 1k AFM ground state has been established for UO2; whereas, a FM (111) ground state has been established for NpO2. To analyse these results, band structure calculations have been performed.
