Complete reversal of the atomic unquenched orbital moment by a single electron

Abstract

The orbital angular moment of magnetic atoms adsorbed on surfaces is often quenched as a result of an anisotropic crystal field. Due to spin-orbit coupling, what remains of the orbital moment typically delineates the orientation of the electron spin. These two effects limit the scope of information processing based on these atoms to essentially only one magnetic degree of freedom: the spin. In this work, we gain independent access to both the spin and orbital degrees of freedom of a single atom, inciting and probing excitations of each moment. By coordinating a single Fe atom atop the nitrogen site of the Cu${}_2$N lattice, we realize a single-atom system with a large zero-field splitting--the largest reported for Fe atoms on surfaces--and an unquenched uniaxial orbital moment that closely approaches the free-atom value. We demonstrate a full reversal of the orbital moment through a single-electron tunneling event between the tip and Fe atom, a process that is mediated by a charged virtual state and leaves the spin unchanged. These results, which we corroborate using density functional theory and first-principles multiplet calculations, demonstrate independent control over the spin and orbital degrees of freedom in a single-atom system.

References in corpus (7)

• Reading and Writing Single-Atom Magnets
• Spin decoherence of magnetic atoms on surfaces
• Probing Magnetic Excitations and Correlations in Single and Coupled Spin Systems with Scanning Tunneling Spectroscopy
• A cotunneling mechanism for all-electrical Electron Spin Resonance of single adsorbed atoms
• Dynamical Negative Differential Resistance in Antiferromagnetically Coupled Few-Atom Spin-Chains
• Derivation of the spin Hamiltonians for Fe in MgO
• Atomically crafted spin lattices as model systems for quantum magnetism

Cited by in corpus (7)

• Ferromagnetism on an atom-thick and extended 2D-metal-organic framework
• A theoretical review on the single-impurity electron spin resonance on surfaces
• Efficient Ab-initio Multiplet Calculations for Magnetic Adatoms on MgO
• Trends in the hyperfine interactions of magnetic adatoms on thin insulating layers
• Microscopic theory of spin-relaxation of a single Fe adatom coupled to substrate vibrations
• Inelastic electron tunneling through adatoms and molecular nanomagnets
• Interplay of magnetic states and hyperfine fields of iron dimers on MgO(001)