Unprecedented Electronic Structure, Magnetism, and Anisotropy in Rare Earth Intermetallics

We investigate magnetic rare earth intermetallics with quantum properties. Many quantum features of rare earth intermetallics are consistent with the past research, but some of the findings are seemingly contradictory. The disagreement is not caused by numerical errors or accidental mistakes but reflects how the many-electron nature of the rare-earth 4f electrons is interpreted by crystal-field and local spin density approximation with onsite electron correlation and spin orbit coupling theories [Das et. al, PRB 100, 024419 (2019)]. The two-sublattice crystal-field theory describes a broad variety of physical properties exhibited by rare earth transition metals, such as the temperature dependence of magnetization and anisotropy, but it is not a first-principles approach. By contrast, our first-principles approach yields a substantial orbital-moment quenching, which violates Hund's rules and is contradictory to conventional knowledge accumulated over decades of rare-earth research. Rationalizing the orbital-moment quenching in terms of the dependence of the 4f charge distribution on the magnetization angle, we argue that medium- and long-run future research will be necessary to reconcile experiment, sublattice models, and first-principle calculations in rare earth intermetallics.