Direct Electrical Access to the Spin Manifolds of Individual Lanthanide Atoms

Lanthanide atoms show long magnetic lifetimes because of their strongly localized 4f electrons, but electrical control of their spins has been difficult because of their closed valence shell configurations. We achieved electron spin resonance of individual lanthanide atoms using a scanning tunneling microscope to probe the atoms bound to a protective insulating film. The atoms on this surface formed a singly charged cation state having an unpaired 6s electron, enabling tunnel current to access their 4f electrons. Europium spectra display a rich array of transitions among the 54 combined electron and nuclear spin states. In contrast, samarium's ground state is a Kramers doublet with a very large g-factor of 5. These results demonstrate that all-electronic sensing and control of individual lanthanide spins is possible for quantum devices and spin-based electronics by using their rarely observed monovalent cation state.