Observation and electric current control of a local spin in a single-molecule magnet

TLDR

In molecular spintronics, a molecule’s spin state can be switched by altering its structure. The study aims to switch the spin of a TbPc₂ double‑decker complex on Au(111) on and off by applying an electric current through a scanning tunnelling microscope. This is achieved by using current pulses to rotate the upper phthalocyanine ligand, which shifts frontier‑orbital energies and quenches the π‑electron spin. The dI/dV spectra reveal a Kondo peak from an unpaired π‑orbital spin that disappears and reappears when the ligand is rotated, demonstrating reversible switching that could encode information at the single‑molecule level.

Abstract

In molecular spintronics, the spin state of a molecule may be switched on and off by changing the molecular structure. Here, we switch on and off the molecular spin of a double-decker bis(phthalocyaninato)terbium(III) complex (TbPc2) adsorbed on an Au(111) surface by applying an electric current via a scanning tunnelling microscope. The dI/dV curve of the tunnelling current recorded onto a TbPc2 molecule shows a Kondo peak, the origin of which is an unpaired spin of a π-orbital of a phthalocyaninato (Pc) ligand. By applying controlled current pulses, we could rotate the upper Pc ligand in TbPc2, leading to the disappearance and reappearance of the Kondo resonance. The rotation shifts the molecular frontier-orbital energies, quenching the π-electron spin. Reversible switching between two stable ligand orientations by applying a current pulse should make it possible to code information at the single-molecule level. In molecular spintronics, the spin state of a molecule may be switched by changing the molecular structure. Here, the spin of a single-molecule magnet is switched by applying an electric current using a scanning tunnelling microscope, which may aid in information coding at the single-molecule level.