Correlation of Kondo effect and molecular conformation of the acceptor molecule in the TTF-TCNE charge transfer complex

Stoll, P.; Lotze, Christian; Ladenthin, Janina N.; Umbach, Tobias Reinhard; Fernández-Torrente, I.; Franke, Katharina J.

doi:10.1088/1361-648x/aae502

Cited by 7 publications

(7 citation statements)

References 28 publications

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“…Thus, different TTF-TCNE phases with different stoichiometries are possible on the Ag(111) surface, even though only the 1:1 stoichiometry can be found in bulk form. Incidentally, only the 1:1 TTF-TCNE phase has been reported when TTF and TCNE are adsorbed on Au(111) . Being that silver is much more reactive than gold, these two facts seem to suggest that charge transfer from the substrate could be determinant in allowing the existence of different phases.…”

Section: Resultsmentioning

confidence: 99%

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Metal-Coordination Network vs Charge Transfer Complex: The Importance of the Surface

et al. 2020

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Contrary to expectations based on solution chemistry, scanning tunneling microscopy results show that, on a Ag(111) surface, the formation of a TTF-TCNE charge transfer complex is favored over an already existent Ag-TCNE coordination network. Density functional theory calculations show that the reason behind this apparent abnormal behavior relies on the much stronger interaction of the Ag adatoms with the Ag crystal when compared to TTF. These results demonstrate that the standard hierarchy of intermolecular interactions must be carefully revised for organic systems adsorbed on solid surfaces, which may have important consequences for the development of organic-based devices.

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Section: Resultsmentioning

confidence: 99%

“…Incidentally, only the 1:1 TTF-TCNE phase has been reported when TTF and TCNE are adsorbed on Au(111). 21 Being that silver is much more reactive than gold, these two facts seem to suggest that charge transfer from the substrate could be determinant in allowing the existence of different phases.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Metal-Coordination Network vs Charge Transfer Complex: The Importance of the Surface

et al. 2020

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“…The Kondo effect can act as evidence for spin polarization on adsorbates [15][16][17]. Furthermore, being able to control the Kondo effect chemically or mechanically [18][19][20][21][22][23][24][25][26] might be interesting for spintronic applications such as tailoring electronic and magnetic properties at organic-semiconductor-metal interfaces [27].…”

Section: Introductionmentioning

confidence: 99%

Local Decomposition of Hybridization Functions: Chemical Insight into Correlated Molecular Adsorbates

Bahlke¹,

Schneeberger²,

Herrmann

2021

Preprint

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Hybridization functions are an established tool for investigating the coupling between a correlated subsystem (often a single transition metal atom) and its uncorrelated environment (the substrate and any ligands present). The hybridization function can provide valuable insight into why and how strong correlation features such as the Kondo effect can be chemically controlled in certain molecular adsorbates. To deepen this insight, we introduce a local decomposition of the hybridization function, based on a truncated cluster approach, enabling us to study individual effects on this function coming from specific parts of the systems (e.g., the surface, ligands, or parts of larger ligands). It is shown that a truncated-cluster approach can reproduce the Co 3d and Mn 3d hybridization functions from periodic boundary conditions in Co(CO)4/Cu(001) and MnPc/Ag(001) qualitatively well. By locally decomposing the hybridization functions, it is demonstrated at which energies the transition metal atoms are mainly hybridized with the substrate or with the ligand. For the Kondo-active the 3dx2−y2 orbital in Co(CO)4/Cu(001), the hybridization function at the Fermi energy is substrate-dominated, so we can assign its enhancement compared with ligand-free Co to an indirect effect of ligand–substrate interactions. In MnPc/Ag(001), the same is true for the Kondo-active orbital, but for two other orbitals, there are both direct and indirect effects of the ligand, together resulting in such strong screening that their potential Kondo activity is suppressed. A local decomposition of hybridization functions could also be useful in other areas, such as analyzing the electrode self-energies in molecular junctions.

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“…If such interaction takes place in impure metallic systems, the resistivity starts to grow with decreasing temperature as opposed to its pure counterpart, which has been first described by J. Kondo in dilute magnetic alloys in 1964 1-3 . Since then, the Kondo effect has become a subject of intensive research since it allows insight into fascinating aspects of electron correlation 4 and can give information on the electronic and atomistic structure of molecular adsorbates [5][6][7][8][9][10][11][12][13][14] .…”

Section: Introductionmentioning

confidence: 99%

Co(CO)n/Cu(001): Towards understanding chemical control of the Kondo effect

Bahlke

Wahl

Diekhöner

et al. 2019

Journal of Applied Physics

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The Kondo effect is a many-body phenomenon allowing insight into the electronic and atomistic structure of spin-polarized adsorbates on metal surfaces. Its chemical control is intriguing because it deepens such insight, but the underlying mechanisms are only partly understood. We study the effect of increasing the number of CO ligands attached to a cobalt adatom on copper(001), which correlates with an increase in the Kondo temperature T K experimentally (P. Wahl et al, Phy.Rev. Lett. 95, 166601 (2005)), by solving an Anderson impurity model parametrized by density functional theory (DFT++). Our results suggest that the orbital responsible for the Kondo effect is d x 2 −y 2 for the tetracarbonyl, and its combination with d z 2 for the dicarbonyl. The molecular structures depend considerably on the approximate exchange-correlation functional, which may be related to the known difficulty of describing CO binding to metal surfaces. These structural variations strongly affect the Kondo properties, which is not only a concern for predictive studies, but also of interest for detecting mechanical deformations and for understanding the effect of tip-adsorbate interactions in the scanning tunneling microscope. Still, by constraining the tetracarbonyl to C 4v symmetry, as suggested by experimental data, we find structures compatible with the experimental trend for T K (employing BLYP-D3+U). This is not possible for the tricarbonyl despite the range of computational parameters scanned. For the tetra-and dicarbonyl, the increased T K correlates with a larger hybridization function at the Fermi level, which we trace back to an increased interaction of the Co 3d orbitals with the ligands. 1 arXiv:1811.00569v1 [cond-mat.str-el] 1 Nov 2018 H = νσ νĉ † ν,σĉ ν,σ + νiσ [V νiĉ † ν,σd i,σ + V * νid † i,σĉ ν,σ ] + iσ id † iσd iσ + 1 2 ijkl σσwhere, i is the energy of the ith localized d orbital of the impurity (here defined as the Co atom), and ν is the kinetic energy of the bath electron ν (in this work, the remainder of the

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Correlation of Kondo effect and molecular conformation of the acceptor molecule in the TTF-TCNE charge transfer complex

Cited by 7 publications

References 28 publications

Metal-Coordination Network vs Charge Transfer Complex: The Importance of the Surface

Metal-Coordination Network vs Charge Transfer Complex: The Importance of the Surface

Local Decomposition of Hybridization Functions: Chemical Insight into Correlated Molecular Adsorbates

Co(CO)n/Cu(001): Towards understanding chemical control of the Kondo effect

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