Multiorbital Interactions and Spin Polarization in Single Rare-Earth Adatoms

Surface-adsorbed rare-earth nanostructures are ideal platforms to investigate the interplay between intra-atomic interactions and multiorbital spin configurations. However, addressing these properties has posed severe experimental and theoretical challenges. Here, we use the orbital selectivity offered by x-ray absorption spectroscopy to quantify the Coulomb integrals of Nd atoms on conductive surfaces directly from experimental quantities, as well as the variation of individual orbital occupation upon cluster nucleation. Using x-ray magnetic circular dichroism we identify magnetic moments of the order of 0.1-0.2 μB at the 5d orbitals and their magnetic coupling with the 4f spins. Our results validate orbital-resolved x-ray spectroscopy as a reliable method for quantifying complex multiorbital interactions in surface-adsorbed lanthanides.