1
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Šćepanović S, Kimouche A, Mirković J, Sadiek G, Klamroth T, Hassanien A. Delocalized spin states at zigzag termini of armchair graphene nanoribbon. Sci Rep 2024; 14:11641. [PMID: 38773311 PMCID: PMC11109170 DOI: 10.1038/s41598-024-62624-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2024] [Accepted: 05/20/2024] [Indexed: 05/23/2024] Open
Abstract
Using scanning tunneling microscopy and spectroscopy we demonstrate a revival of magnetism in 7-armchair nanoribbon by unpassivated atoms at the termini. Namely, a pair of intense Kondo resonances emerges at the peripheries of zigzag terminus revealing the many-body screening effects of local magnetic moments. Although Kondo resonance originates from a missing local orbital, it extends to a distance of 2.5 nm along the edge of the ribbon. The results are complemented by density functional theory calculations which suggest a possible coupling between Kondo states despite screening effects of substrate electrons. These findings indicate a possibility to restore intrinsic magnetic ordering in graphene nanoribbon without major structural modifications.
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Affiliation(s)
- Stefan Šćepanović
- Jozef Stefan Institute, 39 Jamova, 1000, Ljubljana, Slovenia
- Faculty of Sciences, University of Montenegro, 81000, Podgorica, Montenegro
| | - Amina Kimouche
- Institute of Physics and Astronomy, University of Potsdam, 14476, Potsdam, Germany
| | - Jovan Mirković
- Faculty of Sciences, University of Montenegro, 81000, Podgorica, Montenegro
| | - Gehad Sadiek
- Department of Applied Physics and Astronomy, University of Sharjah, 27272, Sharjah, UAE
| | - Tillmann Klamroth
- Institute of Chemistry, University of Potsdam, 14476, Potsdam, Germany
| | - Abdou Hassanien
- Jozef Stefan Institute, 39 Jamova, 1000, Ljubljana, Slovenia.
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2
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Meng X, Möller J, Menchón RE, Weismann A, Sánchez-Portal D, Garcia-Lekue A, Herges R, Berndt R. Kondo Effect of Co-Porphyrin: Remarkable Sensitivity to Adsorption Sites and Orientations. NANO LETTERS 2024; 24:180-186. [PMID: 38150551 DOI: 10.1021/acs.nanolett.3c03669] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2023]
Abstract
We investigated the Kondo effect of cobalt(II)-5-15-bis(4'-bromophenyl)-10,20-bis(4'-iodophenyl)porphyrin (CoTPPBr2I2) molecules on Au(111) with low-temperature scanning tunneling microscopy under ultrahigh vacuum conditions. The molecules exhibit four adsorption configurations at the top and bridge sites of the surface with different molecular orientations. The Kondo resonance shows extraordinary sensitivity to the adsorption configuration. By switching the molecule between different configurations, the Kondo temperature is varied over a wide range from ≈8 up to ≈250 K. Density functional theory calculations reveal that changes of the adsorption configuration lead to distinct variations of the hybridization between the molecule and the surface. Furthermore, we show that surface reconstruction plays a significant role for the molecular Kondo effect.
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Affiliation(s)
- Xiangzhi Meng
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität, 24098 Kiel, Germany
| | - Jenny Möller
- Otto-Diels-Institut für Organische Chemie, Christian-Albrechts-Universität, 24098 Kiel, Germany
| | - Rodrigo E Menchón
- Donostia International Physics Center (DIPC), 20018 Donostia-San Sebastián, Spain
- Facultad de Ciencias Exactas, Ingeniría y Agrimensura (FCEIA), Instituto de Física Rosario (IFIR), 2000 Rosario, Argentina
- Universidad Nacional de Rosario (UNR), 2000 Rosario, Argentina
| | - Alexander Weismann
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität, 24098 Kiel, Germany
| | - Daniel Sánchez-Portal
- Donostia International Physics Center (DIPC), 20018 Donostia-San Sebastián, Spain
- Centro de Física de Materiales CSIC-UPV/EHU, 20018 Donostia-San Sebastián, Spain
| | - Aran Garcia-Lekue
- Donostia International Physics Center (DIPC), 20018 Donostia-San Sebastián, Spain
- Ikerbasque, Basque Foundation for Science, 48013 Bilbao, Spain
| | - Rainer Herges
- Otto-Diels-Institut für Organische Chemie, Christian-Albrechts-Universität, 24098 Kiel, Germany
| | - Richard Berndt
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität, 24098 Kiel, Germany
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3
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Noei N, Mozara R, Montero AM, Brinker S, Ide N, Guimarães FSM, Lichtenstein AI, Berndt R, Lounis S, Weismann A. Manipulating the Spin Orientation of Co Atoms Using Monatomic Cu Chains. NANO LETTERS 2023; 23:8988-8994. [PMID: 37782684 DOI: 10.1021/acs.nanolett.3c02532] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/04/2023]
Abstract
Harnessing the spin of single atoms is at the heart of quantum information nanotechnology based on magnetic concepts. By attaching single Co atoms to monatomic Cu chains, we demonstrate the ability to control the spin orientation by the atomic environment. Due to spin-orbit coupling (SOC), the spin is tilted by ≈58° from the surface normal toward the chain as evidenced by inelastic tunneling spectroscopy. These findings are reproduced by density functional theory calculations and have implications for Co atoms on pristine Cu(111), which are believed to be Kondo systems. Our quantum Monte Carlo calculations suggest that SOC suppresses the Kondo effect of Co atoms at chains and on the flat surface. Our work impacts the fundamental understanding of low-energy excitations in nanostructures on surfaces and demonstrates the ability to manipulate atomic-scale magnetic moments, which can have tremendous implications for quantum devices.
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Affiliation(s)
- Neda Noei
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, 24098 Kiel, Germany
| | - Roberto Mozara
- Institut für Theoretische Physik, Universität Hamburg, 20355 Hamburg, Germany
| | - Ana M Montero
- Peter Grünberg Institut and Institute for Advanced Simulation, Forschungszentrum Jülich & JARA, 52425 Jülich, Germany
| | - Sascha Brinker
- Peter Grünberg Institut and Institute for Advanced Simulation, Forschungszentrum Jülich & JARA, 52425 Jülich, Germany
| | - Niklas Ide
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, 24098 Kiel, Germany
| | - Filipe S M Guimarães
- Jülich Supercomputing Centre, Forschungszentrum Jülich and JARA, 52425 Jülich, Germany
| | | | - Richard Berndt
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, 24098 Kiel, Germany
| | - Samir Lounis
- Peter Grünberg Institut and Institute for Advanced Simulation, Forschungszentrum Jülich & JARA, 52425 Jülich, Germany
- Faculty of Physics, University of Duisburg-Essen and CENIDE, 47053 Duisburg, Germany
| | - Alexander Weismann
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, 24098 Kiel, Germany
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4
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Vilas-Varela M, Romero-Lara F, Vegliante A, Calupitan JP, Martínez A, Meyer L, Uriarte-Amiano U, Friedrich N, Wang D, Schulz F, Koval NE, Sandoval-Salinas ME, Casanova D, Corso M, Artacho E, Peña D, Pascual JI. On-Surface Synthesis and Characterization of a High-Spin Aza-[5]-Triangulene. Angew Chem Int Ed Engl 2023; 62:e202307884. [PMID: 37604782 DOI: 10.1002/anie.202307884] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2023] [Revised: 08/11/2023] [Accepted: 08/17/2023] [Indexed: 08/23/2023]
Abstract
Triangulenes are a class of open-shell triangular graphene flakes with total spin increasing with their size. In the last years, on-surface-synthesis strategies have permitted fabricating and engineering triangulenes of various sizes and structures with atomic precision. However, direct proof of the increasing total spin with their size remains elusive. In this work, we report the combined in-solution and on-surface synthesis of a large nitrogen-doped triangulene (aza-[5]-triangulene) on a Au(111) surface, and the detection of its high-spin ground state. Bond-resolved scanning tunneling microscopy images uncovered radical states distributed along the zigzag edges, which were detected as weak zero-bias resonances in scanning tunneling spectra. These spectral features reveal the partial Kondo screening of a high-spin state. Through a combination of several simulation tools, we find that the observed distribution of radical states is explained by a quintet ground state (S=2), instead of the quartet state (S=3/2) expected for the neutral species. This confirms that electron transfer to the metal substrate raises the spin of the ground state. We further provide a qualitative description of the change of (anti)aromaticity introduced by N-substitution, and its role in the charge stabilization on a surface, resulting in an S=2 aza-triangulene on Au(111).
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Affiliation(s)
- Manuel Vilas-Varela
- Centro Singular de Investigación en Química Biolóxica e Materiais Moleculares (CiQUS) and Departamento de Química Orgánica, Universidade de Santiago de Compostela, 15782-, Santiago de Compostela, Spain
| | | | | | - Jan Patrick Calupitan
- Centro de Física de Materiales CSIC/UPV-EHU-Materials Physics Center, 20018, Donostia-San Sebastián, Spain
- Donostia International Physics Center (DIPC), 20018, Donostia-San Sebastián, Spain
| | - Adrián Martínez
- Centro Singular de Investigación en Química Biolóxica e Materiais Moleculares (CiQUS) and Departamento de Química Orgánica, Universidade de Santiago de Compostela, 15782-, Santiago de Compostela, Spain
| | - Lorenz Meyer
- CIC nanoGUNE-BRTA, 20018, Donostia-San Sebastián, Spain
| | | | | | - Dongfei Wang
- CIC nanoGUNE-BRTA, 20018, Donostia-San Sebastián, Spain
| | - Fabian Schulz
- CIC nanoGUNE-BRTA, 20018, Donostia-San Sebastián, Spain
| | | | | | - David Casanova
- Donostia International Physics Center (DIPC), 20018, Donostia-San Sebastián, Spain
- Ikerbasque, Basque Foundation for Science, 48009, Bilbao, Spain
| | - Martina Corso
- Centro de Física de Materiales CSIC/UPV-EHU-Materials Physics Center, 20018, Donostia-San Sebastián, Spain
| | - Emilio Artacho
- CIC nanoGUNE-BRTA, 20018, Donostia-San Sebastián, Spain
- Ikerbasque, Basque Foundation for Science, 48009, Bilbao, Spain
- Theory of Condensed Matter, Cavendish Laboratory, University of Cambridge, J. J. Thomson Ave., Cambridge, CB3 0HE, UK
| | - Diego Peña
- Centro Singular de Investigación en Química Biolóxica e Materiais Moleculares (CiQUS) and Departamento de Química Orgánica, Universidade de Santiago de Compostela, 15782-, Santiago de Compostela, Spain
| | - José Ignacio Pascual
- CIC nanoGUNE-BRTA, 20018, Donostia-San Sebastián, Spain
- Ikerbasque, Basque Foundation for Science, 48009, Bilbao, Spain
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5
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Li C, Robles R, Lorente N, Mahatha SK, Rohlf S, Rossnagel K, Barla A, Sorokin BV, Rusponi S, Ohresser P, Realista S, Martinho PN, Jasper-Toennies T, Weismann A, Berndt R, Gruber M. Large Orbital Moment of Two Coupled Spin-Half Co Ions in a Complex on Gold. ACS NANO 2023. [PMID: 37224165 DOI: 10.1021/acsnano.3c01595] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The magnetic properties of transition-metal ions are generally described by the atomic spins of the ions and their exchange coupling. The orbital moment, usually largely quenched due the ligand field, is then seen as a perturbation. In such a scheme, S = 1/2 ions are predicted to be isotropic. We investigate a Co(II) complex with two antiferromagnetically coupled 1/2 spins on Au(111) using low-temperature scanning tunneling microscopy, X-ray magnetic circular dichroism, and density functional theory. We find that each of the Co ions has an orbital moment comparable to that of the spin, leading to magnetic anisotropy, with the spins preferentially oriented along the Co-Co axis. The orbital moment and the associated magnetic anisotropy is tuned by varying the electronic coupling of the molecule to the substrate and the microscope tip. These findings show the need to consider the orbital moment even in systems with strong ligand fields. As a consequence, the description of S = 1/2 ions becomes strongly modified, which have important consequences for these prototypical systems for quantum operations.
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Affiliation(s)
- Chao Li
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, 24098 Kiel, Germany
| | - Roberto Robles
- Centro de Física de Materiales CFM/MPC (CSIC-UPV/EHU), 20018 Donostia-San Sebastián, Spain
| | - Nicolas Lorente
- Centro de Física de Materiales CFM/MPC (CSIC-UPV/EHU), 20018 Donostia-San Sebastián, Spain
- Donostia International Physics Center (DIPC), 20018 Donostia-San Sebastian, Spain
| | - Sanjoy Kr Mahatha
- Ruprecht Haensel Laboratory, Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany
| | - Sebastian Rohlf
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, 24098 Kiel, Germany
| | - Kai Rossnagel
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, 24098 Kiel, Germany
- Ruprecht Haensel Laboratory, Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany
| | - Alessandro Barla
- Istituto di Struttura della Materia (ISM), Consiglio Nazionale delle Ricerche (CNR), 34149 Trieste, Italy
| | - Boris V Sorokin
- Institute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL), Station 3, 1015 Lausanne, Switzerland
| | - Stefano Rusponi
- Institute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL), Station 3, 1015 Lausanne, Switzerland
| | | | - Sara Realista
- Centro de Química Estrutural, Institute of Molecular Sciences, Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade de Lisboa, Campo Grande, 1749-016 Lisboa, Portugal
| | - Paulo N Martinho
- Centro de Química Estrutural, Institute of Molecular Sciences, Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade de Lisboa, Campo Grande, 1749-016 Lisboa, Portugal
| | - Torben Jasper-Toennies
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, 24098 Kiel, Germany
| | - Alexander Weismann
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, 24098 Kiel, Germany
| | - Richard Berndt
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, 24098 Kiel, Germany
| | - Manuel Gruber
- Faculty of Physics and CENIDE, University of Duisburg-Essen, 47057 Duisburg, Germany
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6
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Turco E, Bernhardt A, Krane N, Valenta L, Fasel R, Juríček M, Ruffieux P. Observation of the Magnetic Ground State of the Two Smallest Triangular Nanographenes. JACS AU 2023; 3:1358-1364. [PMID: 37234116 PMCID: PMC10207087 DOI: 10.1021/jacsau.2c00666] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/06/2022] [Revised: 02/02/2023] [Accepted: 02/02/2023] [Indexed: 05/27/2023]
Abstract
Fusion of three benzene rings in a triangular fashion gives rise to the smallest open-shell graphene fragment, the phenalenyl radical, whose π-extension leads to an entire family of non-Kekulé triangular nanographenes with high-spin ground states. Here, we report the first synthesis of unsubstituted phenalenyl on a Au(111) surface, which is achieved by combining in-solution synthesis of the hydro-precursor and on-surface activation by atomic manipulation, using the tip of a scanning tunneling microscope. Single-molecule structural and electronic characterizations confirm its open-shell S = 1/2 ground state that gives rise to Kondo screening on the Au(111) surface. In addition, we compare the phenalenyl's electronic properties with those of triangulene, the second homologue in the series, whose S = 1 ground state induces an underscreened Kondo effect. Our results set a new lower size limit in the on-surface synthesis of magnetic nanographenes that can serve as building blocks for the realization of new exotic quantum phases of matter.
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Affiliation(s)
- Elia Turco
- nanotech@surfaces
Laboratory, Empa−Swiss Federal Laboratories
for Materials Science and Technology, 8600 Dübendorf, Switzerland
| | - Annika Bernhardt
- Department
of Chemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Nils Krane
- nanotech@surfaces
Laboratory, Empa−Swiss Federal Laboratories
for Materials Science and Technology, 8600 Dübendorf, Switzerland
| | - Leoš Valenta
- Department
of Chemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Roman Fasel
- nanotech@surfaces
Laboratory, Empa−Swiss Federal Laboratories
for Materials Science and Technology, 8600 Dübendorf, Switzerland
- Department
of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, 3012 Bern, Switzerland
| | - Michal Juríček
- Department
of Chemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Pascal Ruffieux
- nanotech@surfaces
Laboratory, Empa−Swiss Federal Laboratories
for Materials Science and Technology, 8600 Dübendorf, Switzerland
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7
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Ma C, Wang J, Ma H, Yin R, Zhao XJ, Du H, Meng X, Ke Y, Hu W, Li B, Tan S, Tan YZ, Yang J, Wang B. Remote-Triggered Domino-like Cyclodehydrogenation in Second-Layer Topological Graphene Nanoribbons. J Am Chem Soc 2023; 145:10126-10135. [PMID: 37097709 DOI: 10.1021/jacs.3c00563] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/26/2023]
Abstract
Cyclodehydrogenation reactions in the on-surface synthesis of graphene nanoribbons (GNRs) usually involve a series of Csp2-Csp2 and/or Csp2-Csp3 couplings and just happen on uncovered metal or metal oxide surfaces. It is still a big challenge to extend the growth of second-layer GNRs in the absence of necessary catalytic sites. Here, we demonstrate the direct growth of topologically nontrivial GNRs via multistep Csp2-Csp2 and Csp2-Csp3 couplings in the second layer by annealing designed bowtie-shaped precursor molecules over one monolayer on the Au(111) surface. After annealing at 700 K, most of the polymerized chains that appear in the second layer covalently link to the first-layer GNRs that have partially undergone graphitization. Following annealing at 780 K, the second-layer GNRs are formed and linked to the first-layer GNRs. Benefiting from the minimized local steric hindrance of the precursors, we suggest that the second-layer GNRs undergo domino-like cyclodehydrogenation reactions that are remotely triggered at the link. We confirm the quasi-freestanding behaviors in the second-layer GNRs by measuring the quasiparticle energy gap of topological bands and the tunable Kondo resonance from topological end spins using scanning tunneling microscopy/spectroscopy combined with first-principles calculations. Our findings pave the avenue to diverse multilayer graphene nanostructures with designer quantum spins and topological states for quantum information science.
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Affiliation(s)
- Chuanxu Ma
- Hefei National Research Center for Physical Sciences at the Microscale and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- Hefei National Laboratory, University of Science and Technology of China, Hefei, Anhui 230088, China
| | - Jufeng Wang
- Hefei National Research Center for Physical Sciences at the Microscale and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Huanhuan Ma
- Hefei National Research Center for Physical Sciences at the Microscale and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Ruoting Yin
- Hefei National Research Center for Physical Sciences at the Microscale and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Xin-Jing Zhao
- Collaborative Innovation Center of Chemistry for Energy Materials, State Key Laboratory for Physical Chemistry of Solid Surfaces, and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, Fujian 361005, China
| | - Hongjian Du
- Hefei National Research Center for Physical Sciences at the Microscale and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- Hefei National Laboratory, University of Science and Technology of China, Hefei, Anhui 230088, China
| | - Xinyong Meng
- Hefei National Research Center for Physical Sciences at the Microscale and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Yifan Ke
- Hefei National Research Center for Physical Sciences at the Microscale and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Wei Hu
- Hefei National Research Center for Physical Sciences at the Microscale and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- Hefei National Laboratory, University of Science and Technology of China, Hefei, Anhui 230088, China
| | - Bin Li
- Hefei National Research Center for Physical Sciences at the Microscale and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- Hefei National Laboratory, University of Science and Technology of China, Hefei, Anhui 230088, China
| | - Shijing Tan
- Hefei National Research Center for Physical Sciences at the Microscale and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- Hefei National Laboratory, University of Science and Technology of China, Hefei, Anhui 230088, China
| | - Yuan-Zhi Tan
- Collaborative Innovation Center of Chemistry for Energy Materials, State Key Laboratory for Physical Chemistry of Solid Surfaces, and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, Fujian 361005, China
| | - Jinlong Yang
- Hefei National Research Center for Physical Sciences at the Microscale and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- Hefei National Laboratory, University of Science and Technology of China, Hefei, Anhui 230088, China
| | - Bing Wang
- Hefei National Research Center for Physical Sciences at the Microscale and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- Hefei National Laboratory, University of Science and Technology of China, Hefei, Anhui 230088, China
- New Cornerstone Science Laboratory, Shenzhen 518054, China
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8
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He Y, Li N, Castelli IE, Li R, Zhang Y, Zhang X, Li C, Wang B, Gao S, Peng L, Hou S, Shen Z, Lü JT, Wu K, Hedegård P, Wang Y. Observation of Biradical Spin Coupling through Hydrogen Bonds. PHYSICAL REVIEW LETTERS 2022; 128:236401. [PMID: 35749188 DOI: 10.1103/physrevlett.128.236401] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Revised: 02/09/2022] [Accepted: 05/03/2022] [Indexed: 06/15/2023]
Abstract
Investigation of intermolecular electron spin interaction is of fundamental importance in both science and technology. Here, radical pairs of all-trans retinoic acid molecules on Au(111) are created using an ultralow temperature scanning tunneling microscope. Antiferromagnetic coupling between two radicals is identified by magnetic-field-dependent spectroscopy. The measured exchange energies are from 0.1 to 1.0 meV. The biradical spin coupling is mediated through O─H⋯O hydrogen bonds, as elucidated from analysis combining density functional theory calculation and a modern version of valence bond theory.
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Affiliation(s)
- Yang He
- Center for Carbon-Based Electronics and Key Laboratory for the Physics and Chemistry of Nanodevices, Department of Electronics, Peking University, Beijing 100871, China
| | - Na Li
- Center for Carbon-Based Electronics and Key Laboratory for the Physics and Chemistry of Nanodevices, Department of Electronics, Peking University, Beijing 100871, China
| | - Ivano E Castelli
- Department of Energy Conversion and Storage, Technical University of Denmark, DK-2800 Kongens Lyngby, Denmark
| | - Ruoning Li
- Center for Carbon-Based Electronics and Key Laboratory for the Physics and Chemistry of Nanodevices, Department of Electronics, Peking University, Beijing 100871, China
| | - Yajie Zhang
- Center for Carbon-Based Electronics and Key Laboratory for the Physics and Chemistry of Nanodevices, Department of Electronics, Peking University, Beijing 100871, China
| | - Xue Zhang
- Center for Carbon-Based Electronics and Key Laboratory for the Physics and Chemistry of Nanodevices, Department of Electronics, Peking University, Beijing 100871, China
| | - Chao Li
- Center for Carbon-Based Electronics and Key Laboratory for the Physics and Chemistry of Nanodevices, Department of Electronics, Peking University, Beijing 100871, China
| | - Bingwu Wang
- Beijing National Laboratory for Molecular Science, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
| | - Song Gao
- Beijing National Laboratory for Molecular Science, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
| | - Lianmao Peng
- Center for Carbon-Based Electronics and Key Laboratory for the Physics and Chemistry of Nanodevices, Department of Electronics, Peking University, Beijing 100871, China
| | - Shimin Hou
- Center for Carbon-Based Electronics and Key Laboratory for the Physics and Chemistry of Nanodevices, Department of Electronics, Peking University, Beijing 100871, China
| | - Ziyong Shen
- Center for Carbon-Based Electronics and Key Laboratory for the Physics and Chemistry of Nanodevices, Department of Electronics, Peking University, Beijing 100871, China
| | - Jing-Tao Lü
- School of Physics, Institute for Quantum Science and Engineering, and Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, 430074 Wuhan, China
| | - Kai Wu
- Beijing National Laboratory for Molecular Science, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
| | - Per Hedegård
- Niels Bohr Institute, University of Copenhagen, DK-2100 Copenhagen, Denmark
| | - Yongfeng Wang
- Center for Carbon-Based Electronics and Key Laboratory for the Physics and Chemistry of Nanodevices, Department of Electronics, Peking University, Beijing 100871, China
- Beijing Academy of Quantum Information Sciences, Beijing 100193, China
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9
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Lu S, Nam H, Xiao P, Liu M, Guo Y, Bai Y, Cheng Z, Deng J, Li Y, Zhou H, Henkelman G, Fiete GA, Gao HJ, MacDonald AH, Zhang C, Shih CK. PTCDA Molecular Monolayer on Pb Thin Films: An Unusual π-Electron Kondo System and Its Interplay with a Quantum-Confined Superconductor. PHYSICAL REVIEW LETTERS 2021; 127:186805. [PMID: 34767397 DOI: 10.1103/physrevlett.127.186805] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/24/2020] [Accepted: 09/28/2021] [Indexed: 06/13/2023]
Abstract
The hybridization of magnetism and superconductivity has been an intriguing playground for correlated electron systems, hosting various novel physical phenomena. Usually, localized d or f electrons are central to magnetism. In this study, by placing a PTCDA (3,4,9,10-perylene tetracarboxylic dianhydride) molecular monolayer on ultrathin Pb films, we built a hybrid magnetism/superconductivity (M/SC) system consisting of only sp electronic levels. The magnetic moments reside in the unpaired molecular orbital originating from interfacial charge transfers. We reported distinctive tunneling spectroscopic features of such a Kondo screened π electron impurity lattice on a superconductor in the regime of T_{K}≫Δ, suggesting the formation of a two-dimensional bound states band. Moreover, moiré superlattices with tunable twist angle and the quantum confinement in the ultrathin Pb films provide easy and flexible implementations to tune the interplay between the Kondo physics and the superconductivity, which are rarely present in M/SC hybrid systems.
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Affiliation(s)
- Shuangzan Lu
- School of Physics and Technology, Wuhan University, Wuhan 430072, China
| | - Hyoungdo Nam
- Department of Physics, the University of Texas at Austin, Austin, Texas 78712, USA
| | - Penghao Xiao
- Department of Chemistry, the University of Texas at Austin, Austin, Texas 78712, USA
- Department of Physics & Atmospheric Science, Dalhousie University, Halifax, Nova Scotia B3H4J5, Canada
| | - Mengke Liu
- Department of Physics, the University of Texas at Austin, Austin, Texas 78712, USA
| | - Yanping Guo
- School of Physics and Technology, Wuhan University, Wuhan 430072, China
| | - Yusong Bai
- School of Physics and Technology, Wuhan University, Wuhan 430072, China
| | - Zhengbo Cheng
- School of Physics and Technology, Wuhan University, Wuhan 430072, China
| | - Jinghao Deng
- School of Physics and Technology, Wuhan University, Wuhan 430072, China
| | - Yanxing Li
- Department of Physics, the University of Texas at Austin, Austin, Texas 78712, USA
| | - Haitao Zhou
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Graeme Henkelman
- Department of Chemistry, the University of Texas at Austin, Austin, Texas 78712, USA
| | - Gregory A Fiete
- Department of Physics, Northeastern University, Boston, Massachusetts 02115, USA
- Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Hong-Jun Gao
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Allan H MacDonald
- Department of Physics, the University of Texas at Austin, Austin, Texas 78712, USA
| | - Chendong Zhang
- School of Physics and Technology, Wuhan University, Wuhan 430072, China
| | - Chih-Kang Shih
- Department of Physics, the University of Texas at Austin, Austin, Texas 78712, USA
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10
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Žonda M, Stetsovych O, Korytár R, Ternes M, Temirov R, Raccanelli A, Tautz FS, Jelínek P, Novotný T, Švec M. Resolving Ambiguity of the Kondo Temperature Determination in Mechanically Tunable Single-Molecule Kondo Systems. J Phys Chem Lett 2021; 12:6320-6325. [PMID: 34228474 DOI: 10.1021/acs.jpclett.1c01544] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Determination of the molecular Kondo temperature (TK) poses a challenge in most cases when the experimental temperature cannot be tuned to a sufficient extent. We show how this ambiguity can be resolved if additional control parameters are present, such as magnetic field and mechanical gating. We record the evolution of the differential conductance by lifting an individual molecule from the metal surface with the tip of a scanning tunneling microscope. By fitting the measured conductance spectra with the single impurity Anderson model we are able to demonstrate that the lifting tunes the junction continuously from the strongly correlated Kondo-singlet to the free spin-1/2 ground state. In the crossover regime, where TK is similar to the temperature of experiment, the fitting yields ambiguous estimates of TK varying by an order of magnitude. We show that analysis of the conductance measured in two distinct external magnetic fields can be used to resolve this problem.
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Affiliation(s)
- Martin Žonda
- Department of Condensed Matter Physics, Faculty of Mathematics and Physics, Charles University, Ke Karlovu 5, CZ-121 16 Praha 2, Czech Republic
- Institute of Physics, Albert Ludwig University of Freiburg, Hermann-Herder-Strasse 3, 79104 Freiburg, Germany
| | - Oleksandr Stetsovych
- Institute of Physics, Czech Academy of Sciences, Cukrovarnická 10, CZ-162 00 Praha 6, Czech Republic
| | - Richard Korytár
- Department of Condensed Matter Physics, Faculty of Mathematics and Physics, Charles University, Ke Karlovu 5, CZ-121 16 Praha 2, Czech Republic
| | - Markus Ternes
- Institute of Physics II B, RWTH Aachen University, 52074 Aachen, Germany
- Peter Grünberg Institut (PGI-3), Forschungszentrum Jülich, Jülich Germany
| | - Ruslan Temirov
- Peter Grünberg Institut (PGI-3), Forschungszentrum Jülich, Jülich Germany
- Faculty of Mathematics and Natural Sciences, Institute of Physics II, University of Cologne, 50937 Cologne, Germany
| | - Andrea Raccanelli
- Peter Grünberg Institut (Cryo-Lab), Forschungszentrum Jülich, JülichGermany
| | - F Stefan Tautz
- Peter Grünberg Institut (PGI-3), Forschungszentrum Jülich, Jülich Germany
- Fundamentals of Future Information Technology, Jülich Aachen Research Alliance (JARA), Jülich, Germany
- Institute of Physics IV A, RWTH Aachen University, Aachen, Germany
| | - Pavel Jelínek
- Institute of Physics, Czech Academy of Sciences, Cukrovarnická 10, CZ-162 00 Praha 6, Czech Republic
- RCPTM, Palacky University, Šlechtitelu 27, 783 71 Olomouc, Czech Republic
| | - Tomáš Novotný
- Department of Condensed Matter Physics, Faculty of Mathematics and Physics, Charles University, Ke Karlovu 5, CZ-121 16 Praha 2, Czech Republic
| | - Martin Švec
- Institute of Physics, Czech Academy of Sciences, Cukrovarnická 10, CZ-162 00 Praha 6, Czech Republic
- RCPTM, Palacky University, Šlechtitelu 27, 783 71 Olomouc, Czech Republic
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11
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Farinacci L, Ahmadi G, Ruby M, Reecht G, Heinrich BW, Czekelius C, von Oppen F, Franke KJ. Interfering Tunneling Paths through Magnetic Molecules on Superconductors: Asymmetries of Kondo and Yu-Shiba-Rusinov Resonances. PHYSICAL REVIEW LETTERS 2020; 125:256805. [PMID: 33416394 DOI: 10.1103/physrevlett.125.256805] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Revised: 10/10/2020] [Accepted: 11/19/2020] [Indexed: 06/12/2023]
Abstract
Magnetic adsorbates on superconductors induce a Kondo resonance outside and Yu-Shiba-Rusinov (YSR) bound states inside the superconducting energy gap. When probed by scanning tunneling spectroscopy, the associated differential-conductance spectra frequently exhibit characteristic bias-voltage asymmetries. Here, we observe correlated variations of Kondo and YSR asymmetries across an Fe-porphyrin molecule adsorbed on Pb(111). We show that both asymmetries originate in interfering tunneling paths via a spin-carrying orbital and the highest occupied molecular orbital (HOMO). Strong evidence for this model comes from nodal planes of the HOMO, where tunneling reveals symmetric Kondo and YSR resonances. Our results establish an important mechanism for the asymmetries of Kondo and YSR line shapes.
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Affiliation(s)
- Laëtitia Farinacci
- Fachbereich Physik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
| | - Gelavizh Ahmadi
- Fachbereich Physik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
| | - Michael Ruby
- Fachbereich Physik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
| | - Gaël Reecht
- Fachbereich Physik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
| | - Benjamin W Heinrich
- Fachbereich Physik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
| | - Constantin Czekelius
- Institut für Organische Chemie und Makromolekulare Chemie, Heinrich-Heine-Universität Düsseldorf, Universitätsstrasse 1, 40225Düsseldorf, Germany
| | - Felix von Oppen
- Dahlem Center for Complex Quantum Systems and Fachbereich Physik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
| | - Katharina J Franke
- Fachbereich Physik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
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12
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Yang H, Li YY, Liu TT, Guan DD, Wang SY, Zheng H, Liu C, Fu L, Jia JF. Multiple In-Gap States Induced by Topological Surface States in the Superconducting Topological Crystalline Insulator Heterostructure Sn_{1-x}Pb_{x}Te-Pb. PHYSICAL REVIEW LETTERS 2020; 125:136802. [PMID: 33034492 DOI: 10.1103/physrevlett.125.136802] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2020] [Accepted: 08/04/2020] [Indexed: 06/11/2023]
Abstract
Superconducting topological crystalline insulators (TCIs) have been proposed to be a new type of topological superconductor where multiple Majorana zero modes may coexist under the protection of lattice symmetries. The bulk superconductivity of TCIs has been realized, but it is quite challenging to detect the superconductivity of topological surface states inside their bulk superconducting gaps. Here, we report high-resolution scanning tunneling spectroscopy measurements on lateral Sn_{1-x}Pb_{x}Te-Pb heterostructures using superconducting tips. Both the bulk superconducting gap and the multiple in-gap states with energy differences of ∼0.3 meV can be clearly resolved on TCI Sn_{1-x}Pb_{x}Te at 0.38 K. Quasiparticle interference measurements further confirm the in-gap states are gapless. Our work demonstrates that the unique topological superconductivity of a TCI can be directly distinguished in the density of states, which helps to further investigate the multiple Dirac and Majorana fermions inside the superconducting gap.
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Affiliation(s)
- Hao Yang
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Shenyang National Laboratory for Materials Science, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Yao-Yi Li
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Shenyang National Laboratory for Materials Science, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
- CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing 100190, China
- Tsung-Dao Lee Institute, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Teng-Teng Liu
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Shenyang National Laboratory for Materials Science, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Dan-Dan Guan
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Shenyang National Laboratory for Materials Science, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
- CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing 100190, China
- Tsung-Dao Lee Institute, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Shi-Yong Wang
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Shenyang National Laboratory for Materials Science, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
- CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing 100190, China
- Tsung-Dao Lee Institute, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Hao Zheng
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Shenyang National Laboratory for Materials Science, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
- CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing 100190, China
- Tsung-Dao Lee Institute, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Canhua Liu
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Shenyang National Laboratory for Materials Science, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
- CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing 100190, China
- Tsung-Dao Lee Institute, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Liang Fu
- Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Jin-Feng Jia
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Shenyang National Laboratory for Materials Science, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
- CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing 100190, China
- Tsung-Dao Lee Institute, Shanghai Jiao Tong University, Shanghai 200240, China
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13
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Abstract
The transfer of the inherent bistability of spin crossover compounds to surfaces has attracted considerable interest in recent years. The deposition of the complexes on surfaces allows investigating them individually and to further understand the microscopic mechanisms at play. Moreover, it offers the prospect of engineering switchable functional surfaces. We review recent progress in the field with a particular focus on the challenges and limits associated with the dominant experimental techniques used, namely near-edge X-ray absorption fine structure (NEXAFS) spectroscopy and scanning tunneling microscopy (STM). One of the main difficulties in NEXAFS-based experiments is to ascertain that the complexes are in direct contact with the surfaces. We show that molecular coverage determination based on the amplitude of the edge-jump of interest is challenging because the latter quantity depends on the substrate. Furthermore, NEXAFS averages the signals of a large number of molecules, which may be in different states. In particular, we highlight that the signal of fragmented molecules is difficult to distinguish from that of intact and functional ones. In contrast, STM allows investigating individual complexes, but the identification of the spin states is at best done indirectly. As quite some of the limits of the techniques are becoming apparent as the field is gaining maturity, their detailed descriptions will be useful for future investigations and for taking a fresh look at earlier reports.
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14
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Néel N, Shao B, Wehling TO, Kröger J. Manipulation of the two-site Kondo effect in linear CoCu n CoCu m clusters. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:055303. [PMID: 31604345 DOI: 10.1088/1361-648x/ab4d17] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Artificially assembled linear atomic clusters, CoCu n CoCu m , are used to explore variations of the Kondo effect at the two Co sites. For all investigated Cu n chain lengths ([Formula: see text]) the addition of a single Cu atom to one edge Co atom of the chain ([Formula: see text]) strongly reduces the amplitude of the Abrikosov-Suhl-Kondo resonance of that Co atom. Concomitantly, the resonance line width is more than halved. On the contrary, the Kondo effect of the opposite edge Co atom remains unaffected. Hybridization together with the linear geometry of the cluster are likely to drive the effect.
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Affiliation(s)
- N Néel
- Institut für Physik, Technische Universität Ilmenau, D-98693 Ilmenau, Germany
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15
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Bocquet M, Lorente N, Berndt R, Gruber M. Spin in a Closed‐Shell Organic Molecule on a Metal Substrate Generated by a Sigmatropic Reaction. Angew Chem Int Ed Engl 2019; 58:821-824. [PMID: 30422385 DOI: 10.1002/anie.201812121] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Indexed: 11/07/2022]
Affiliation(s)
- Marie‐Laure Bocquet
- PASTEURDépartement de chimieÉcole normale supérieurePSL UniversitySorbonne UniversitéCNRS 75005 Paris France
| | - Nicolas Lorente
- Centro de Fısica de Materiales CFM/MPC (CSIC-UPV/EHU) Paseo Manuel de Lardizabal 5 20018 Donostia-San Sebastian Spain
- Donostia International Physics Center (DIPC) Paseo Manuel de Lardizabal 4 20018 Donostia-San Sebastian Spain
| | - Richard Berndt
- Institut für Experimentelle und Angewandte PhysikChristian-Albrechts-Universität 24098 Kiel Germany
| | - Manuel Gruber
- Institut für Experimentelle und Angewandte PhysikChristian-Albrechts-Universität 24098 Kiel Germany
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16
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Bocquet M, Lorente N, Berndt R, Gruber M. Spin in a Closed‐Shell Organic Molecule on a Metal Substrate Generated by a Sigmatropic Reaction. Angew Chem Int Ed Engl 2018. [DOI: 10.1002/ange.201812121] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Marie‐Laure Bocquet
- PASTEURDépartement de chimieÉcole normale supérieurePSL UniversitySorbonne UniversitéCNRS 75005 Paris France
| | - Nicolas Lorente
- Centro de Fısica de Materiales CFM/MPC (CSIC-UPV/EHU) Paseo Manuel de Lardizabal 5 20018 Donostia-San Sebastian Spain
- Donostia International Physics Center (DIPC) Paseo Manuel de Lardizabal 4 20018 Donostia-San Sebastian Spain
| | - Richard Berndt
- Institut für Experimentelle und Angewandte PhysikChristian-Albrechts-Universität 24098 Kiel Germany
| | - Manuel Gruber
- Institut für Experimentelle und Angewandte PhysikChristian-Albrechts-Universität 24098 Kiel Germany
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