Giant magnetic anisotropy of Pb atoms in 3d-based magnets

Electronic structure analysis is performed to study the properties of several Pb-containing 3d-intermetallics. Our study reveals that binary metastable Co3Pb and Fe3Pb intermetallic compounds exhibit very attractive intrinsic magnetic properties. We primarily focus on the magnetic anisotropic properties arising from the high spin-orbit coupling of the Pb atom. Decomposing the total anisotropy into intra- and interatomic contributions reveals a significant deviation from single ion anisotropy model with strong symmetric anisotropic pair interactions present. Furthermore, we consider magnetic properties of ternary Pb-based 3d-intermetallics which recently have been reported as stable or metastable. Giant magnetic anisotropy is found on Pb atoms in these systems. The origin of such strong anisotropy in La18Co28Pb3 appears from two sources: spin-orbit and interelectronic Breit couplings. The significance of Breit interaction for magnetic anisotropy in bulk systems has not been reported previously. It is expected that Breit coupling induced anisotropy is dominating in magnetic Pb-based magnets with lower dimensionality including thin films.