Kondo resonance in the conductance of CoPc/Au(111) and TBrPP-Co/Cu(111)

Aguiar-Hualde, J. M.; Chiappe, G.; Louis, E.; Anda, E. V.; Simonin, J.

doi:10.1103/physrevb.79.155415

Cited by 13 publications

(10 citation statements)

References 39 publications

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Section: Mechanism: Activated Screening Enables Kondo Effectmentioning

confidence: 99%

“…A possible explanation for such activation of Kondo screening has been recently put forward theoretically, proposing that molecular distortion in phthalocyanines activates Kondo screening as a consequence of ligand lobe− lobe interactions. 52,53 Such lobe−lobe interactions are expected to manifest in changes in the LDOS on the ligand and a broken particle−hole symmetry (i.e., E o ≠ E F ). 52 Our data agree with several aspects of these predictions: Prior to activation, "O-up" TiOPc molecules show clear nodes between all four ligand lobes, which appear as a low-signal cross aligned with the crystallographic directions in constant current STM images (Figure 2a); in contrast, activation leaves one well-resolved node that runs centrally through the molecule in the [11̅ 0] direction.…”

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confidence: 99%

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Ensemble Control of Kondo Screening in Molecular Adsorbates

Maughan

Zahl

Sutter

et al. 2017

J. Phys. Chem. Lett.

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Switching the magnetic properties of organic semiconductors on a metal surface has thus far largely been limited to molecule-by-molecule tip-induced transformations in scanned probe experiments. Here we demonstrate with molecular resolution that collective control of activated Kondo screening can be achieved in thin-films of the organic semiconductor titanyl phthalocyanine on Cu(110) to obtain tunable concentrations of Kondo impurities. Using low-temperature scanning tunneling microscopy and spectroscopy, we show that a thermally activated molecular distortion dramatically shifts surface-molecule coupling and enables ensemble-level control of Kondo screening in the interfacial spin system. This is accompanied by the formation of a temperature-dependent Abrikosov-Suhl-Kondo resonance in the local density of states of the activated molecules. This enables coverage-dependent control over activation to the Kondo screening state. Our study thus advances the versatility of molecular switching for Kondo physics and opens new avenues for scalable bottom-up tailoring of the electronic structure and magnetic texture of organic semiconductor interfaces at the nanoscale.

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Section: Mechanism: Activated Screening Enables Kondo Effectmentioning

confidence: 99%

mentioning

confidence: 99%

Ensemble Control of Kondo Screening in Molecular Adsorbates

Maughan

Zahl

Sutter

et al. 2017

J. Phys. Chem. Lett.

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“…[4][5][6][7] More recently, Kondo-like signals have been reported in magnetic molecules adsorbed on metallic substrates, [8][9][10][11][12] stimulating significant advances on the theory side. [13][14][15][16][17][18][19][20][21] For both single magnetic atoms and magnetic molecules on metallic surfaces, the low-bias conductance measured by STM acquires a characteristic Fano lineshape, from which the Kondo temperature T K is usually inferred from fittings to well-known equations. 22,23 Such expressions, however, do not offer estimates for T K , and rather treat it as a phenomenological fitting parameter.…”

Section: Introductionmentioning

confidence: 99%

Many-body electronic structure and Kondo properties of cobalt-porphyrin molecules

et al. 2009

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We use a combination of first-principles many-body methods and the numerical renormalization-group technique to study the Kondo regime of cobalt-porphyrin compounds adsorbed on a Cu͑111͒ surface. We find the Kondo temperature to be highly sensitive to both molecule charging and distance to the surface, which can explain the variations observed in recent scanning-tunneling-spectroscopy measurements. We discuss the importance of many-body effects in the molecular electronic structure controlling this phenomenon and suggest scenarios where enhanced temperatures can be achieved in experiments.

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“…is the Green function of the isolated cluster. In this work G (±) 0 is obtained either by means of a finite U slave bosons (SB) approach [13,14,15,16] or by exact diagonalization in which case the result corresponds to the Embedding Cluster Approximation (ECA) method [8,10,17,18].…”

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confidence: 99%

Kondo effect in transport through molecules adsorbed on metal surfaces: From Fano dips to Kondo peaks

et al. 2007

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The Kondo effect observed in recent STM experiments on transport through CoPc and TBrPP-Co molecules adsorbed on Au(111) and Cu(111) surfaces, respectively, is discussed within the framework of a simple model (Phys. Rev. Lett. 97, 076806 (2006)). It is shown that, in the Kondo regime and by varying the adequate model parameters, it is possible to produce a crossover from a conductance Kondo peak (CoPc) to a conductance Fano dip (TBrPP-Co). In the case of TBrPP-Co/Cu (111) we show that the model reproduces the changes in the shape of the Fano dip, the raising of the Kondo temperature and shifting to higher energies of the dip minimum when the number of nearest neighbors molecules is lowered. These features are in line with experimental observations indicating that our simple model contains the essential physics underlying the transport properties of such complex molecules. [2,3] in transport through a Co atom adsorbed on an Au(111) surface, a great deal of attention has been devoted to investigate, both theoretical and experimentally, such effect in either isolated Co atoms [4,5] or in Co-containing molecules [6,7,8,9] adsorbed on metal surfaces. The possibility of tuning the Kondo temperature [6,9] has been recently demonstrated, increasing considerably the interest of these systems. In particular it has been shown that, the characteristics, and even the existence, of the Kondo resonance can be controlled by distorting a CoPc molecule adsorbed on a Au(111) surface [6]. More recently [9] the Kondo temperature in a TBrPP-Co molecule adsorbed on a Cu(111) surface has been increased by decreasing the number of nearestneighbor TBrPP-Co molecules. The authors of [9] argued that this is due to a reduction of surfaces states when the number of nearest neighbors molecules around a given one is increased.One of the most interesting aspects of those two works is that while in the case of CoPc/Au(111) a Kondo peak was observed, in the experiments on TBrPP-Co/Cu(111) the conductance showed a Fano dip, as in isolated Co atoms adsorbed on metal surfaces [1,4,5]. Those two molecules, although largely different, have two outstanding similarities: i) both have the Co atom in the their geometric centers, and, ii) their STM images show four clearly defined lobes [6]. The enormous complexity of the electronic structure of these molecules and the manybody physics involved hinder a detailed account of these systems. One of the main goals of the present work is to show, using a simple model that catches the most prominent features of both molecules, under which circumstances dips or peaks appear in the transmission.A model Hamiltonian was taken assuming the following small atomic arrangement [8]: a central site with a single atomic orbital, a strong Coulomb repulsion at the Co atom and four lobes of the molecule described by four atomic orbitals placed on a square, which center is the Co atom (see Fig. 1 of Ref.[8]). Two additional orbitals located above and below the Co atom are included to represent the apex of the STM tip and an at...

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Kondo resonance in the conductance of CoPc/Au(111) and TBrPP-Co/Cu(111)

Cited by 13 publications

References 39 publications

Ensemble Control of Kondo Screening in Molecular Adsorbates

Ensemble Control of Kondo Screening in Molecular Adsorbates

Many-body electronic structure and Kondo properties of cobalt-porphyrin molecules

Kondo effect in transport through molecules adsorbed on metal surfaces: From Fano dips to Kondo peaks

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