Direct electrical access to the spin manifolds of individual monovalent lanthanide atoms

TL;DR

This paper demonstrates the first electron spin resonance of individual monovalent lanthanide atoms using STM, enabling electrical control of their spins for quantum and spintronic applications.

Contribution

It introduces a method to electrically access and manipulate the spin states of monovalent lanthanide atoms at the single-atom level, which was previously challenging.

Findings

Electron spin resonance observed in individual lanthanide atoms.

Rich spin transition spectra in europium atoms.

Large g-factor observed in samarium's ground state.

Abstract

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. These atoms were prepared in the monovalent state with 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 an extraordinarily large g-factor of nearly 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.