Probing Magnetism in Self-Assembled Organometallic Complexes using Kondo Spectroscopy

TL;DR

This paper demonstrates a method for self-assembling magnetic organometallic complexes with individual Fe atoms on a silver substrate, revealing their magnetic properties via Kondo spectroscopy and providing insights into spin control at the atomic level.

Contribution

It introduces a hybrid approach using STM to reliably create and analyze organometallic complexes with tunable spin states, combining experimental and theoretical methods.

Findings

Fe atoms attach under benzene rings forming organometallic complexes.

Kondo signatures reveal magnetic property changes of Fe atoms.

Density functional theory explains the orbital interactions enabling Kondo screening.

Abstract

Control of individual spins at the atomic level holds great promise for miniaturized spintronics, quantum sensing, and quantum information processing. Both single atomic and molecular spin centers are prime candidates for these applications and are often individually addressed and manipulated using scanning tunneling microscopy (STM). In this work, we present a hybrid approach and demonstrate a robust method for self-assembly of magnetic organometallic complexes consisting of individual iron (Fe) atoms and molecules on a silver substrate using STM. We employ two types of molecules, bis(dibenzoylmethane) copper(II) [Cu(dbm)2] and iron phthalocyanine (FePc). We show that in both cases the Fe atoms preferentially attach underneath the benzene ring ligand of the molecules, effectively forming an organometallic half-sandwich arene complex, Fe(C6H6), that is akin to the properties of metallocenes. In both situations, a molecule can be combined with up to two Fe atoms. In addition, we observe a change in the magnetic properties of the attached Fe atoms in scanning tunneling spectroscopy, revealing a distinct Kondo signature at the Fe sites. We explain the latter using density functional theory calculations, and find that the bond formation between the Fe 3d-orbitals and the benzene {\pi}-molecular orbitals creates a favorable situation for Kondo screening of the d_xz- and d_yz-like orbitals. Thus, this work establishes a reliable design principle for forming hybrid organometallic complexes and simultaneous tuning of their atomic spin states.