Switching Molecular Kondo Effect via Supramolecular Interaction

Abstract

We apply supramolecular assembly to control the adsorption configuration of Co-porphyrin molecules on Au(111) and Cu(111) surfaces. By means of cryogenic scanning tunneling microscopy, we reveal that the Kondo effect associated with the Co center is absent or present in different supramolecular systems. We perform first-principles calculations to obtain spin-polarized electronic structures and compute the Kondo temperatures using the Anderson impurity model. The switching behavior is traced to varied molecular adsorption heights in different supramolecular structures. These findings unravel that a competition between intermolecular interactions and molecule-substrate interactions subtly regulates the molecular Kondo effect in supramolecular systems.

Ensemble Control of Kondo Screening in Molecular Adsorbates

“…30,48,49 In particular, the closely related system of CuPc/Ag(110) has been shown to undergo electron transfer, 36 and surfaceinduced electron transfer has also been shown for FePc on Cu(111). 50 More generally, surfaceinduced electron transfer has been implicated in the Kondo physics of a range of metal phthalocyanines, 27,37,47 and for some of these generation or quenching of a spin moment 28 and redistribution of spin density throughout the macrocycle have been demonstrated. 51 We thus consider electron transfer the most likely origin of the observed spin moment in TiOPc/Cu(110).…”

“…These experiments include studies of the effects on spin correlation induced in individual molecules by manipulating coordination chemistry, [17][18][19][20] chemical bonding, 21 or adsorption geometry. [22][23][24] Building on single molecule experiments, other studies have documented the influence of self-assembly, 25,26 tip-assisted assembly, 27 supramolecular interaction, 28 and radical chemistry on various molecular Kondo systems. 29 Beyond the mere existence of Kondo screening, switching and controlling the magnetic state of a Kondo impurity is of particular importance in the light of information storage and computing.…”

Dioxygen at Biomimetic Single Metal-Atom Sites: Stabilization or Activation? The Case of CoTPyP/Au(111)

“…The spin-down channel shifts by more than 2 eV above Fermi, thus becoming empty. This is a crucial point in order to get insight into the O 2 ligation mechanism [6,70,71], which, as we will see, will involve the whole Co 3d configuration and not just the 3d z 2 as recently and differently prospected in [68]. When the dioxygen molecule is let interact with the CoTPyP/Au 13 cluster ( Fig.…”

“…We have therefore to consider that in our simulation the replacement of the Au(111) termination with the Au 13 cluster results in a weaker gold interaction with the molecule's periphery. Nevertheless, since the goal of the simulation was to get insight into the O 2 -Co-Au bond and the related charge redistribution trans-effects, we adopted the computationally cheaper Au cluster configuration that allowed the correct reproduction of the electronic configuration of the system, in agreement with previous literature on the full Au(111) termination [68]. The calculated spin-polarized projection densities of states (SP-PDOS) of Co 3d z 2 orbital are plotted in Fig.…”

Electron–phonon coupling in engineered magnetic molecules

“…The magnetic molecules were synthesized in situ through chemical reactions between non-metallic porphyrin-based molecules and magnetic (Co, Cr) atoms, an established procedure to create and study exotic molecules in a highly controlled environment. 6,9,[19][20][21] Conductance measurements through molecules at low temperatures reveal pronounced Kondo resonances at zero bias and additional Kondo resonance replicas observed at higher voltages in vibrating CoTPyP molecules. The Kondo resonance replicas are observed only in the presence of electron-phonon interactions and are associated with creation and destruction of phonons.…”