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

Marc Philipp Bahlke, Peter Wahl, Lars Diekhöner, Carmen Herrmann

Research output: Contribution to journalJournal articleResearchpeer-review

1 Citation (Scopus)

Abstract

The Kondo effect is a many-body phenomenon, allowing insight into the electronic and atomistic structure of magnetic 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 [Wahl et al., Phys. Rev. Lett. 95, 166601 (2005)], by solving an Anderson impurity model parametrized by the density functional theory. 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 4 v 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 3 d orbitals with the ligands.

Original languageEnglish
Article number142910
JournalJournal of Applied Physics
Volume125
Issue number14
Number of pages13
ISSN0021-8979
DOIs
Publication statusPublished - 1 Apr 2019

Fingerprint

Kondo effect
metal surfaces
orbitals
ligands
adatoms
molecular structure
cobalt
microscopes
interactions
density functional theory
electronic structure
trends
copper
impurities
scanning
symmetry
temperature

Cite this

Bahlke, Marc Philipp ; Wahl, Peter ; Diekhöner, Lars ; Herrmann, Carmen. / Co(CO)n/Cu(001) : Towards understanding chemical control of the Kondo effect. In: Journal of Applied Physics. 2019 ; Vol. 125, No. 14.
@article{3effda7b5b784aa3b5ab1f10d44e3b4e,
title = "Co(CO)n/Cu(001): Towards understanding chemical control of the Kondo effect",
abstract = "The Kondo effect is a many-body phenomenon, allowing insight into the electronic and atomistic structure of magnetic 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 [Wahl et al., Phys. Rev. Lett. 95, 166601 (2005)], by solving an Anderson impurity model parametrized by the density functional theory. 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 4 v 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 3 d orbitals with the ligands.",
author = "Bahlke, {Marc Philipp} and Peter Wahl and Lars Diekh{\"o}ner and Carmen Herrmann",
year = "2019",
month = "4",
day = "1",
doi = "10.1063/1.5079518",
language = "English",
volume = "125",
journal = "Journal of Applied Physics",
issn = "0021-8979",
publisher = "American Institute of Physics",
number = "14",

}

Co(CO)n/Cu(001) : Towards understanding chemical control of the Kondo effect. / Bahlke, Marc Philipp; Wahl, Peter; Diekhöner, Lars; Herrmann, Carmen.

In: Journal of Applied Physics, Vol. 125, No. 14, 142910 , 01.04.2019.

Research output: Contribution to journalJournal articleResearchpeer-review

TY - JOUR

T1 - Co(CO)n/Cu(001)

T2 - Towards understanding chemical control of the Kondo effect

AU - Bahlke, Marc Philipp

AU - Wahl, Peter

AU - Diekhöner, Lars

AU - Herrmann, Carmen

PY - 2019/4/1

Y1 - 2019/4/1

N2 - The Kondo effect is a many-body phenomenon, allowing insight into the electronic and atomistic structure of magnetic 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 [Wahl et al., Phys. Rev. Lett. 95, 166601 (2005)], by solving an Anderson impurity model parametrized by the density functional theory. 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 4 v 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 3 d orbitals with the ligands.

AB - The Kondo effect is a many-body phenomenon, allowing insight into the electronic and atomistic structure of magnetic 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 [Wahl et al., Phys. Rev. Lett. 95, 166601 (2005)], by solving an Anderson impurity model parametrized by the density functional theory. 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 4 v 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 3 d orbitals with the ligands.

UR - http://www.scopus.com/inward/record.url?scp=85063965359&partnerID=8YFLogxK

U2 - 10.1063/1.5079518

DO - 10.1063/1.5079518

M3 - Journal article

VL - 125

JO - Journal of Applied Physics

JF - Journal of Applied Physics

SN - 0021-8979

IS - 14

M1 - 142910

ER -