1
|
Rothe K, Néel N, Kröger J. Unveiling the nature of atomic defects in graphene on a metal surface. BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2024; 15:416-425. [PMID: 38655541 PMCID: PMC11035987 DOI: 10.3762/bjnano.15.37] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/31/2023] [Accepted: 03/18/2024] [Indexed: 04/26/2024]
Abstract
Low-energy argon ion bombardment of graphene on Ir(111) induces atomic-scale defects at the surface. Using a scanning tunneling microscope, the two smallest defects appear as a depression without discernible interior structure suggesting the presence of vacancy sites in the graphene lattice. With an atomic force microscope, however, only one kind can be identified as a vacancy defect with four missing carbon atoms, while the other kind reveals an intact graphene sheet. Spatially resolved spectroscopy of the differential conductance and the measurement of total-force variations as a function of the lateral and vertical probe-defect distance corroborate the different character of the defects. The tendency of the vacancy defect to form a chemical bond with the microscope probe is reflected by the strongest attraction at the vacancy center as well as by hysteresis effects in force traces recorded for tip approach to and retraction from the Pauli repulsion range of vertical distances.
Collapse
Affiliation(s)
- Karl Rothe
- Institut für Physik, Technische Universität Ilmenau, D-98693 Ilmenau, Germany
| | - Nicolas Néel
- Institut für Physik, Technische Universität Ilmenau, D-98693 Ilmenau, Germany
| | - Jörg Kröger
- Institut für Physik, Technische Universität Ilmenau, D-98693 Ilmenau, Germany
| |
Collapse
|
2
|
Meng Q, Zhang J, Zhang Y, Chu W, Mao W, Zhang Y, Yang J, Luo Y, Dong Z, Hou JG. Local heating and Raman thermometry in a single molecule. SCIENCE ADVANCES 2024; 10:eadl1015. [PMID: 38232173 DOI: 10.1126/sciadv.adl1015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2023] [Accepted: 12/15/2023] [Indexed: 01/19/2024]
Abstract
Because of the nonequilibrium nature of thermal effects at the nanoscale, the characterization of local thermal effects within a single molecule is highly challenging. Here, we demonstrate a way to characterize the local thermal properties of a single fullerene (C60) molecule during current-induced heating processes through tip-enhanced anti-Stokes Raman spectroscopy. Although the measured vibron populations are far from equilibrium with the environment, we can still define an "effective temperature (Teff)" statistically via a Bose-Einstein distribution, suggesting a local equilibrium within the molecule. With increased current heating, Teff is found to rise up to about 1150 K until the C60 cage is decomposed. Such a decomposition temperature is similar to that reported for ensemble C60 samples, thus justifying the validity of our methodology. Moreover, the possible reaction pathway and product can be identified because of the chemical sensitivity of Raman spectroscopy. Our findings provide a practical method for noninvasively detecting the local heating effect inside a single molecule under nonequilibrium conditions.
Collapse
Affiliation(s)
- Qiushi 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 230026, China
- Hefei National Laboratory, University of Science and Technology of China, Hefei 230088, China
| | - Junxian Zhang
- 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 230026, China
| | - Yao Zhang
- 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 230026, China
- Hefei National Laboratory, University of Science and Technology of China, Hefei 230088, China
- School of Physics and Department of Chemical Physics, University of Science and Technology of China, Hefei 230026, China
| | - Weizhe Chu
- 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 230026, China
| | - Wenjie Mao
- 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 230026, China
| | - Yang Zhang
- 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 230026, China
- Hefei National Laboratory, University of Science and Technology of China, Hefei 230088, China
- School of Physics and Department of Chemical Physics, University of Science and Technology of China, Hefei 230026, 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 230026, China
- Hefei National Laboratory, University of Science and Technology of China, Hefei 230088, China
- School of Physics and Department of Chemical Physics, University of Science and Technology of China, Hefei 230026, China
| | - Yi Luo
- 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 230026, China
- Hefei National Laboratory, University of Science and Technology of China, Hefei 230088, China
- School of Physics and Department of Chemical Physics, University of Science and Technology of China, Hefei 230026, China
| | - Zhenchao Dong
- 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 230026, China
- Hefei National Laboratory, University of Science and Technology of China, Hefei 230088, China
- School of Physics and Department of Chemical Physics, University of Science and Technology of China, Hefei 230026, China
| | - J G Hou
- 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 230026, China
| |
Collapse
|
3
|
Brand J, Leitherer S, Papior NR, Néel N, Lei Y, Brandbyge M, Kröger J. Nonequilibrium Bond Forces in Single-Molecule Junctions. NANO LETTERS 2019; 19:7845-7851. [PMID: 31556298 DOI: 10.1021/acs.nanolett.9b02845] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Passing a current across two touching C60 molecules imposes a nonequilibrium population of bonding and antibonding molecular orbitals, which changes the equilibrium bond character and strength. A current-induced bond force therefore contributes to the total force at chemical-bond distances. The combination of first-principles calculations with scanning probe experiments exploring currents and forces in a wide C60-C60 distance range consistently evidences the presence of current-induced attraction that occurs when the two molecules are on the verge of forming a chemical bond. The unique opportunity to arrange matter at the atomic scale with the atomic force and scanning tunneling microscope tip has enabled closely matching molecular junctions in theory and experiment. The findings consequently represent the first report of current-induced bond forces at the single-molecule level and further elucidate the intimate relation between charge transport and force. The results are relevant to molecular electronics and chemical reactions in the presence of a current.
Collapse
Affiliation(s)
- Jonathan Brand
- Institut für Physik , Technische Universität Ilmenau , D-98693 Ilmenau , Germany
| | - Susanne Leitherer
- Center for Nanostructured Graphene, Department of Physics , Technical University of Denmark , DK-2800 Kongens Lyngby , Denmark
| | - Nick R Papior
- Department of Applied Mathematics and Computer Science , Technical University of Denmark , DK-2800 Kongens Lyngby , Denmark
| | - Nicolas Néel
- Institut für Physik , Technische Universität Ilmenau , D-98693 Ilmenau , Germany
| | - Yong Lei
- Institut für Physik , Technische Universität Ilmenau , D-98693 Ilmenau , Germany
| | - Mads Brandbyge
- Center for Nanostructured Graphene, Department of Physics , Technical University of Denmark , DK-2800 Kongens Lyngby , Denmark
| | - Jörg Kröger
- Institut für Physik , Technische Universität Ilmenau , D-98693 Ilmenau , Germany
| |
Collapse
|
4
|
Karan S, García C, Karolak M, Jacob D, Lorente N, Berndt R. Spin Control Induced by Molecular Charging in a Transport Junction. NANO LETTERS 2018; 18:88-93. [PMID: 29232947 DOI: 10.1021/acs.nanolett.7b03411] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The ability of molecules to maintain magnetic multistability in nanoscale-junctions will determine their role in downsizing spintronic devices. While spin-injection from ferromagnetic leads gives rise to magnetoresistance in metallic nanocontacts, nonmagnetic leads probing the magnetic states of the junction itself have been considered as an alternative. Extending this experimental approach to molecular junctions, which are sensitive to chemical parameters, we demonstrate that the electron affinity of a molecule decisively influences its spin transport. We use a scanning tunneling microscope to trap a meso-substituted iron porphyrin, putting the iron center in an environment that provides control of its charge and spin states. A large electron affinity of peripheral ligands is shown to enable switching of the molecular S = 1 ground state found at low electron density to S = 1/2 at high density, while lower affinity keeps the molecule inactive to spin-state transition. These results pave the way for spin control using chemical design and electrical means.
Collapse
Affiliation(s)
- Sujoy Karan
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel , 24098 Kiel, Germany
- Institute of Experimental and Applied Physics, University of Regensburg , 93053 Regensburg, Germany
| | - Carlos García
- Donostia International Physics Center (DIPC), Paseo Manuel de Lardizabal 4, 20018 Donostia-San Sebastián, Spain
| | - Michael Karolak
- Institut für Theoretische Physik und Astrophysik, Universität Würzburg , Am Hubland, 97074 Würzburg, Germany
| | - David Jacob
- Departamento de Física de Materiales, Universidad del País Vasco, UPV/EHU , Av. Tolosa 72, 20018 San Sebastián, Spain
- IKERBASQUE, Basque Foundation for Science, Maria Diaz de Haro 3, 48013 Bilbao, Spain
| | - Nicolás Lorente
- Donostia International Physics Center (DIPC), Paseo Manuel de Lardizabal 4, 20018 Donostia-San Sebastián, Spain
- Centro de Física de Materiales CFM/MPC, CSIC-UPV/EHU , Paseo Manuel de Lardizabal 5, 20018 Donostia-San Sebastián, Spain
| | - Richard Berndt
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel , 24098 Kiel, Germany
| |
Collapse
|
5
|
Hoffmann-Vogel R. Imaging prototypical aromatic molecules on insulating surfaces: a review. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2018; 81:016501. [PMID: 28958993 DOI: 10.1088/1361-6633/aa8fda] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Insulating substrates allow for in-plane contacted molecular electronics devices where the molecule is in contact with the insulator. For the development of such devices it is important to understand the interaction of molecules with insulating surfaces. As substrates, ionic crystals such as KBr, KCl, NaCl and CaF2 are discussed. The surface energies of these substrates are small and as a consequence intrinsic properties of the molecules, such as molecule-molecule interaction, become more important relative to interactions with the substrates. As prototypical molecules, three variants of graphene-related molecules are used, pentacene, [Formula: see text] and PTCDA. Pentacene is a good candidate for molecular electronics applications due to its high charge carrier mobility. It shows mainly an upright standing growth mode and the morphology of the islands is strongly influenced by dewetting. A new second flat-lying phase of the molecule has been observed. Studying the local work function using the Kelvin method reveals details such as line defects in the center of islands. The local work function differences between the upright-standing and flat-lying phase can only be explained by charge transfer that is unusual on ionic crystalline surfaces. [Formula: see text] nucleation and growth is explained by loosely bound molecules at kink sites as nucleation sites. The stability of [Formula: see text] islands as a function of magic numbers is investigated. Peculiar island shapes are obtained from unusual dewetting processes already at work during growth, where molecules 'climb' to the second molecular layer. PTCDA is a prototypical semiconducting molecule with strong quadrupole moment. It grows in the form of elongated islands where the top and the facets can be molecularly resolved. In this way the precise molecular arrangement in the islands is revealed.
Collapse
Affiliation(s)
- R Hoffmann-Vogel
- Physikalisches Institut, Karlsruhe Institute of Technology (KIT), D-76131 Karlsruhe, Germany. Institut für Angewandte Physik, Karlsruhe Institute of Technology (KIT), D-76131 Karlsruhe, Germany
| |
Collapse
|
6
|
Li R, Li N, Wang H, Weismann A, Zhang Y, Hou S, Wu K, Wang Y. Tuning the spin-related transport properties of FePc on Au(111) through single-molecule chemistry. Chem Commun (Camb) 2018; 54:9135-9138. [PMID: 30059079 DOI: 10.1039/c8cc02994f] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Tuning the spin-related transport properties of FePc on Au(111) through single-molecule chemistry.
Collapse
Affiliation(s)
- Ruoning Li
- Key Laboratory for the Physics and Chemistry of Nanodevices
- Department of Electronics
- Peking University
- Beijing 100871
- China
| | - Na Li
- Key Laboratory for the Physics and Chemistry of Nanodevices
- Department of Electronics
- Peking University
- Beijing 100871
- China
| | - Hao Wang
- Key Laboratory for the Physics and Chemistry of Nanodevices
- Department of Electronics
- Peking University
- Beijing 100871
- China
| | - Alexander Weismann
- Institut für Experimentelle und Angewandte Physik
- Christian-Albrechts-Universität zu Kiel
- 24098 Kiel
- Germany
| | - Yajie Zhang
- Key Laboratory for the Physics and Chemistry of Nanodevices
- Department of Electronics
- Peking University
- Beijing 100871
- China
| | - Shimin Hou
- Key Laboratory for the Physics and Chemistry of Nanodevices
- Department of Electronics
- Peking University
- Beijing 100871
- China
| | - Kai Wu
- BNLMS
- College of Chemistry and Molecular Engineering
- Peking University
- Beijing 100871
- China
| | - Yongfeng Wang
- Key Laboratory for the Physics and Chemistry of Nanodevices
- Department of Electronics
- Peking University
- Beijing 100871
- China
| |
Collapse
|
7
|
Zhang Y, Wang Y, Lü JT, Brandbyge M, Berndt R. Mechanochemistry Induced Using Force Exerted by a Functionalized Microscope Tip. Angew Chem Int Ed Engl 2017. [DOI: 10.1002/ange.201704940] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Yajie Zhang
- Key Laboratory for the Physics and Chemistry of Nanodevices; Department of Electronics; Peking University; Beijing 100871 P.R. China
| | - Yongfeng Wang
- Key Laboratory for the Physics and Chemistry of Nanodevices; Department of Electronics; Peking University; Beijing 100871 P.R. China
| | - Jing-Tao Lü
- School of Physics and Wuhan National High Magnetic Field Center; Huazhong University of Science and Technology; Wuhan 430074 China
| | - Mads Brandbyge
- DTU-Nanotech, Department of Micro- and Nanotechnology; Technical University of Denmark; 2800 Kongens Lyngby Denmark
| | - Richard Berndt
- Institut für Experimentelle und Angewandte Physik; Christian-Albrechts Universität zu Kiel; 24098 Kiel Germany
| |
Collapse
|
8
|
Mechanochemistry Induced Using Force Exerted by a Functionalized Microscope Tip. Angew Chem Int Ed Engl 2017; 56:11769-11773. [DOI: 10.1002/anie.201704940] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Revised: 07/03/2017] [Indexed: 11/07/2022]
|
9
|
Brand J, Ribeiro P, Néel N, Kirchner S, Kröger J. Impact of Atomic-Scale Contact Geometry on Andreev Reflection. PHYSICAL REVIEW LETTERS 2017; 118:107001. [PMID: 28339246 DOI: 10.1103/physrevlett.118.107001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2016] [Indexed: 06/06/2023]
Abstract
Charge transport has been examined in junctions comprising the normal-metal tip of a low-temperature scanning tunneling microscope, the surface of a conventional superconductor, and adsorbed C_{60} molecules. The Bardeen-Cooper-Schrieffer energy gap gradually evolves into a zero-bias peak with decreasing electrode separation. The peak is assigned to the spectroscopic signature of Andreev reflection. The conductance due to Andreev reflection is determined by the atomic termination of the tip apex and the molecular adsorption orientation. Transport calculations unveil the finite temperature and the strong molecule-electrode hybridization as the origin to the surprisingly good agreement between spectroscopic data and the Blonder-Tinkham-Klapwijk model that was conceived for macroscopic point contacts.
Collapse
Affiliation(s)
- J Brand
- Institut für Physik, Technische Universität Ilmenau, D-98693 Ilmenau, Germany
| | - P Ribeiro
- CeFEMA, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal
| | - N Néel
- Institut für Physik, Technische Universität Ilmenau, D-98693 Ilmenau, Germany
| | - S Kirchner
- Center for Correlated Matter, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - J Kröger
- Institut für Physik, Technische Universität Ilmenau, D-98693 Ilmenau, Germany
| |
Collapse
|
10
|
Gerhard L, Edelmann K, Homberg J, Valášek M, Bahoosh SG, Lukas M, Pauly F, Mayor M, Wulfhekel W. An electrically actuated molecular toggle switch. Nat Commun 2017; 8:14672. [PMID: 28276442 PMCID: PMC5347093 DOI: 10.1038/ncomms14672] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2016] [Accepted: 01/23/2017] [Indexed: 01/28/2023] Open
Abstract
Molecular electronics is considered a promising approach for future nanoelectronic devices. In order that molecular junctions can be used as electrical switches or even memory devices, they need to be actuated between two distinct conductance states in a controlled and reproducible manner by external stimuli. Here we present a tripodal platform with a cantilever arm and a nitrile group at its end that is lifted from the surface. The formation of a coordinative bond between the nitrile nitrogen and the gold tip of a scanning tunnelling microscope can be controlled by both electrical and mechanical means, and leads to a hysteretic switching of the conductance of the junction by more than two orders of magnitude. This toggle switch can be actuated with high reproducibility so that the forces involved in the mechanical deformation of the molecular cantilever can be determined precisely with scanning tunnelling microscopy. Robust molecular junctions demand highly reproducible switching between two or more well-defined conductance states upon control. Here, Gerhard et al. show the utility of elastic deformation of tripodal spirobifluorene derivatives in the junction of a scanning tunnelling microscope to achieve this goal.
Collapse
Affiliation(s)
- Lukas Gerhard
- Institut für Nanotechnologie, Karlsruhe Institute of Technology, 76344 Eggenstein-Leopoldshafen, Germany
| | - Kevin Edelmann
- Institut für Nanotechnologie, Karlsruhe Institute of Technology, 76344 Eggenstein-Leopoldshafen, Germany.,Physikalisches Institut, Karlsruhe Institute of Technology, 76131 Karlsruhe, Germany
| | - Jan Homberg
- Institut für Nanotechnologie, Karlsruhe Institute of Technology, 76344 Eggenstein-Leopoldshafen, Germany
| | - Michal Valášek
- Institut für Nanotechnologie, Karlsruhe Institute of Technology, 76344 Eggenstein-Leopoldshafen, Germany
| | - Safa G Bahoosh
- Department of Physics, University of Konstanz, 78457 Konstanz, Germany
| | - Maya Lukas
- Institut für Nanotechnologie, Karlsruhe Institute of Technology, 76344 Eggenstein-Leopoldshafen, Germany
| | - Fabian Pauly
- Department of Physics, University of Konstanz, 78457 Konstanz, Germany
| | - Marcel Mayor
- Institut für Nanotechnologie, Karlsruhe Institute of Technology, 76344 Eggenstein-Leopoldshafen, Germany.,Department of Chemistry, University of Basel, St Johanns-Ring 19, 4056 Basel, Switzerland.,Lehn Institute of Functional Materials (LIFM), Sun Yat-Sen University, Guangzhou 510275, China
| | - Wulf Wulfhekel
- Institut für Nanotechnologie, Karlsruhe Institute of Technology, 76344 Eggenstein-Leopoldshafen, Germany.,Physikalisches Institut, Karlsruhe Institute of Technology, 76131 Karlsruhe, Germany
| |
Collapse
|
11
|
Okuyama H, Kitaguchi Y, Hattori T, Ueda Y, Ferrer NG, Hatta S, Aruga T. Adsorbed states of chlorophenol on Cu(110) and controlled switching of single-molecule junctions. J Chem Phys 2016; 144:244703. [PMID: 27369529 DOI: 10.1063/1.4954409] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
A molecular junction of substituted benzene (chlorophenol) is fabricated and controlled by using a scanning tunneling microscope (STM). Prior to the junction formation, the bonding geometry of the molecule on the surface is characterized by STM and electron energy loss spectroscopy (EELS). EELS shows that the OH group of chlorophenol is dissociated on Cu(110) and that the molecule is bonded nearly flat to the surface via an O atom, with the Cl group intact. We demonstrate controlled contact of an STM tip to the "available" Cl group and lift-up of the molecule while it is anchored to the surface via an O atom. The asymmetric bonding motifs of the molecule to the electrodes allow for reversible control of the junction.
Collapse
Affiliation(s)
- H Okuyama
- Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
| | - Y Kitaguchi
- Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
| | - T Hattori
- Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
| | - Y Ueda
- Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
| | - N G Ferrer
- Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
| | - S Hatta
- Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
| | - T Aruga
- Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
| |
Collapse
|
12
|
Scheil K, Gopakumar TG, Bahrenburg J, Temps F, Maurer RJ, Reuter K, Berndt R. Switching of an Azobenzene-Tripod Molecule on Ag(111). J Phys Chem Lett 2016; 7:2080-2084. [PMID: 27193044 DOI: 10.1021/acs.jpclett.6b01011] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The trans-cis isomerization makes azobenzene (AB) a robust molecular switch. Once adsorbed to a metal, however, the switching is inefficient or absent due to rapid excited-state quenching or loss of the trans-cis bistability. We find that tris-[4-(phenylazo)-phenyl]-amine is a rather efficient switch on Ag(111). Using scanning tunneling and atomic force microscopy at submolecular resolution along with density functional theory calculations, we show that the switching process is no trans-cis isomerization but rather a reorientation of the N-N bond of an AB unit. It proceeds through a twisting motion of the azo-bridge that leads to a lateral shift of a phenyl ring. Thus, the role of the Ag substrate is ambivalent. While it suppresses the original bistability of the azobenzene units, it creates a new one by inducing a barrier for the rotation of the N-N bond.
Collapse
Affiliation(s)
- Katharina Scheil
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität , 24098 Kiel, Germany
| | | | - Julia Bahrenburg
- Institut für Physikalische Chemie, Christian-Albrechts-Universität , 24098 Kiel, Germany
| | - Friedrich Temps
- Institut für Physikalische Chemie, Christian-Albrechts-Universität , 24098 Kiel, Germany
| | - Reinhard Johann Maurer
- Lehrstuhl für Theoretische Chemie, Technische Unversität München , 85747 Garching, Germany
| | - Karsten Reuter
- Lehrstuhl für Theoretische Chemie, Technische Unversität München , 85747 Garching, Germany
| | - Richard Berndt
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität , 24098 Kiel, Germany
| |
Collapse
|
13
|
Affiliation(s)
- Gemma C Solomon
- Nano-Science Center and in the Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark
| |
Collapse
|
14
|
Tuning the conductance of H2O@C60 by position of the encapsulated H2O. Sci Rep 2015; 5:17932. [PMID: 26643873 PMCID: PMC4995735 DOI: 10.1038/srep17932] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2015] [Accepted: 09/22/2015] [Indexed: 11/11/2022] Open
Abstract
The change of conductance of single-molecule junction in response to various external stimuli is the fundamental mechanism for the single-molecule electronic devices with multiple functionalities. We propose the concept that the conductance of molecular systems can be tuned from inside. The conductance is varied in C60 with encapsulated H2O, H2O@C60. The transport properties of the H2O@C60-based nanostructure sandwiched between electrodes are studied using first-principles calculations combined with the non-equilibrium Green’s function formalism. Our results show that the conductance of the H2O@C60 is sensitive to the position of the H2O and its dipole direction inside the cage with changes in conductance up to 20%. Our study paves a way for the H2O@C60 molecule to be a new platform for novel molecule-based electronics and sensors.
Collapse
|
15
|
Corso M, Ondráček M, Lotze C, Hapala P, Franke KJ, Jelínek P, Pascual JI. Charge Redistribution and Transport in Molecular Contacts. PHYSICAL REVIEW LETTERS 2015; 115:136101. [PMID: 26451568 DOI: 10.1103/physrevlett.115.136101] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2015] [Indexed: 06/05/2023]
Abstract
The forces between two single molecules brought into contact, and their connection with charge transport through the molecular junction, are studied here using non contact AFM, STM, and density functional theory simulations. A carbon monoxide molecule approaching an acetylene molecule (C_{2}H_{2}) initially feels weak attractive electrostatic forces, partly arising from charge reorganization in the presence of molecular . We find that the molecular contact is chemically passive, and protects the electron tunneling barrier from collapsing, even in the limit of repulsive forces. However, we find subtle conductance and force variations at different contacting sites along the C_{2}H_{2} molecule attributed to a weak overlap of their respective frontier orbitals.
Collapse
Affiliation(s)
- Martina Corso
- Institut für Experimentalphysik, Freie Universität Berlin, 14195 Berlin, Germany
- Centro de Fisica de Materiales CSIC/UPV-EHU, 20018 Donostia-San Sebastian, Spain
- Ikerbasque, Basque Foundation for Science, 48011 Bilbao, Spain
| | - Martin Ondráček
- Institute of Physics of the Academy of Sciences of the Czech Republic, 162 00 Prague, Czech Republic
| | - Christian Lotze
- Institut für Experimentalphysik, Freie Universität Berlin, 14195 Berlin, Germany
| | - Prokop Hapala
- Institute of Physics of the Academy of Sciences of the Czech Republic, 162 00 Prague, Czech Republic
| | - Katharina J Franke
- Institut für Experimentalphysik, Freie Universität Berlin, 14195 Berlin, Germany
| | - Pavel Jelínek
- Institute of Physics of the Academy of Sciences of the Czech Republic, 162 00 Prague, Czech Republic
| | - J Ignacio Pascual
- Institut für Experimentalphysik, Freie Universität Berlin, 14195 Berlin, Germany
- Ikerbasque, Basque Foundation for Science, 48011 Bilbao, Spain
- CIC nanoGUNE, 20018 Donostia-San Sebastian, Spain
| |
Collapse
|
16
|
Zhu C, Wang X. Transport properties of the H2O@C60-dimer-based junction. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2015; 27:375301. [PMID: 26325223 DOI: 10.1088/0953-8984/27/37/375301] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Theoretical predictions play an important role in finding potential applications in molecular electronics. Fullerenes have a number of potential applications, and the charge flow from a single C60 molecule to another becomes more versatile and more interesting after doping. Here, we report the conductance of two H2O@C60 molecules in series order and how the number of encapsulated water molecules influences the transport properties of the junction. Encapsulating an H2O molecule into one of the C60 cages increases the conductance of the dimer. Negative differential resistance is found in the dimer systems, and its peak-to-valley current ratio depends on the number of encapsulated H2O molecules. The conductance of the C60 dimer and the H2O@C60 dimer is two orders of magnitude smaller than that of the C60 monomer. Furthermore, we demonstrate that the conductance of the molecular junctions based on the H2O@C60 dimer can be tuned by moving the encapsulated H2O molecules. The conductance is H2O-position dependent. Our findings indicate that H2O@C60 can be used as a building block in C60-based molecular electronic devices and sensors.
Collapse
Affiliation(s)
- Chengbo Zhu
- Spintronic and Electronic Materials Group, Institute for Superconducting and Electronic Materials, Australian Institute for Innovative Materials, University of Wollongong, North Wollongong, New South Wales 2500, Australia
| | | |
Collapse
|
17
|
Huber F, Matencio S, Weymouth AJ, Ocal C, Barrena E, Giessibl FJ. Intramolecular Force Contrast and Dynamic Current-Distance Measurements at Room Temperature. PHYSICAL REVIEW LETTERS 2015; 115:066101. [PMID: 26296122 DOI: 10.1103/physrevlett.115.066101] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2015] [Indexed: 06/04/2023]
Abstract
Scanning probe microscopy can be used to probe the internal atomic structure of flat organic molecules. This technique requires an unreactive tip and has, until now, been demonstrated only at liquid helium and liquid nitrogen temperatures. We demonstrate intramolecular and intermolecular force contrast at room temperature on PTCDA molecules adsorbed on a Ag/Si(111)-(√[3]×√[3]) surface. The oscillating force sensor allows us to dynamically measure the vertical decay constant of the tunneling current. The precision of this method is increased by quantifying the transimpedance of the current to voltage converter and accounting for the tip oscillation. This measurement yields a clear contrast between neighboring molecules, which we attribute to the different charge states.
Collapse
Affiliation(s)
- F Huber
- Institute of Experimental and Applied Physics, University of Regensburg, 93053 Regensburg, Germany
| | - S Matencio
- Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus de la UAB, 08193 Bellaterra, Spain
| | - A J Weymouth
- Institute of Experimental and Applied Physics, University of Regensburg, 93053 Regensburg, Germany
| | - C Ocal
- Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus de la UAB, 08193 Bellaterra, Spain
| | - E Barrena
- Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus de la UAB, 08193 Bellaterra, Spain
| | - F J Giessibl
- Institute of Experimental and Applied Physics, University of Regensburg, 93053 Regensburg, Germany
| |
Collapse
|
18
|
Reecht G, Bulou H, Scheurer F, Speisser V, Mathevet F, González C, Dappe YJ, Schull G. Pulling and Stretching a Molecular Wire to Tune its Conductance. J Phys Chem Lett 2015; 6:2987-2992. [PMID: 26267192 DOI: 10.1021/acs.jpclett.5b01283] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
A scanning tunnelling microscope is used to pull a polythiophene wire from a Au(111) surface while measuring the current traversing the junction. Abrupt current increases measured during the lifting procedure are associated with the detachment of molecular subunits, in apparent contradiction with the expected exponential decrease of the conductance with wire length. Ab initio simulations reproduce the experimental data and demonstrate that this unexpected behavior is due to release of mechanical stress in the wire, paving the way to mechanically gated single-molecule electronic devices.
Collapse
Affiliation(s)
- Gaël Reecht
- †IPCMS de Strasbourg, UMR 7504 (CNRS - Université de Strasbourg), 67034 Strasbourg, France
| | - Hervé Bulou
- †IPCMS de Strasbourg, UMR 7504 (CNRS - Université de Strasbourg), 67034 Strasbourg, France
| | - Fabrice Scheurer
- †IPCMS de Strasbourg, UMR 7504 (CNRS - Université de Strasbourg), 67034 Strasbourg, France
| | - Virginie Speisser
- †IPCMS de Strasbourg, UMR 7504 (CNRS - Université de Strasbourg), 67034 Strasbourg, France
| | - Fabrice Mathevet
- ‡Institut Parisien de Chimie Moléculaire, Chimie des Polymères, UMR 8232, (CNRS - Université Pierre et Marie Curie), 75252 Paris, France
| | - César González
- §Service de Physique de l'Etat Condensé, DSM/IRAMIS/SPEC, CNRS UMR 3680, CEA Saclay, 91191 Gif sur Yvette cedex, France
| | - Yannick J Dappe
- §Service de Physique de l'Etat Condensé, DSM/IRAMIS/SPEC, CNRS UMR 3680, CEA Saclay, 91191 Gif sur Yvette cedex, France
| | - Guillaume Schull
- †IPCMS de Strasbourg, UMR 7504 (CNRS - Université de Strasbourg), 67034 Strasbourg, France
| |
Collapse
|
19
|
Controlling single-molecule junction conductance by molecular interactions. Sci Rep 2015; 5:11796. [PMID: 26135251 PMCID: PMC4488765 DOI: 10.1038/srep11796] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2015] [Accepted: 06/05/2015] [Indexed: 11/08/2022] Open
Abstract
For the rational design of single-molecular electronic devices, it is essential to understand environmental effects on the electronic properties of a working molecule. Here we investigate the impact of molecular interactions on the single-molecule conductance by accurately positioning individual molecules on the electrode. To achieve reproducible and precise conductivity measurements, we utilize relatively weak π-bonding between a phenoxy molecule and a STM-tip to form and cleave one contact to the molecule. The anchoring to the other electrode is kept stable using a chalcogen atom with strong bonding to a Cu(110) substrate. These non-destructive measurements permit us to investigate the variation in single-molecule conductance under different but controlled environmental conditions. Combined with density functional theory calculations, we clarify the role of the electrostatic field in the environmental effect that influences the molecular level alignment.
Collapse
|
20
|
Kim H, Hasegawa Y. Site-Dependent Evolution of Electrical Conductance from Tunneling to Atomic Point Contact. PHYSICAL REVIEW LETTERS 2015; 114:206801. [PMID: 26047248 DOI: 10.1103/physrevlett.114.206801] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Indexed: 06/04/2023]
Abstract
Using scanning tunneling microscopy (STM), we investigated the evolution of electrical conductance between a Pb tip and Pb(111) surface from tunneling to atomic point contact at a site that was defined with atomic precision. We found that the conductance evolution depended on the contact site, for instance, on-top, bridge, or hollow (hcp and fcc) sites in the Pb lattice. In the transition from tunneling to contact regimes, the conductance measured at the on-top site was enhanced. In the point contact regime, the hollow sites had conductances larger than those of the other sites, and between the hollow sites, the hcp site had a conductance larger than that of the fcc site. We also observed the enhancement and reversal of the apparent height in atomically resolved high-current STM images, consistent with the results of the conductance traces. Our results indicate the importance of atomic configuration in the conductance of atomic junctions and suggest that attractive chemical interactions have a significant role in electron transport between contacting atoms.
Collapse
Affiliation(s)
- Howon Kim
- Institute for Solid State Physics, University of Tokyo 5-1-5, Kashiwa-no-ha, Kashiwa 277-8581, Japan
| | - Yukio Hasegawa
- Institute for Solid State Physics, University of Tokyo 5-1-5, Kashiwa-no-ha, Kashiwa 277-8581, Japan
| |
Collapse
|
21
|
Hellenthal C, Sotthewes K, Siekman MH, Kooij ES, Zandvliet HJW. Closed-loop conductance scanning tunneling spectroscopy: demonstrating the equivalence to the open-loop alternative. BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2015; 6:1116-1124. [PMID: 26171288 PMCID: PMC4464298 DOI: 10.3762/bjnano.6.113] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/11/2014] [Accepted: 04/08/2015] [Indexed: 06/04/2023]
Abstract
We demonstrate the validity of using closed-loop z(V) conductance scanning tunneling spectroscopy (STS) measurements for the determination of the effective tunneling barrier by comparing them to more conventional open-loop I(z) measurements. Through the development of a numerical model, the individual contributions to the effective tunneling barrier present in these experiments, such as the work function and the presence of an image charge, are determined quantitatively. This opens up the possibility of determining tunneling barriers of both vacuum and molecular systems in an alternative and more detailed manner.
Collapse
Affiliation(s)
- Chris Hellenthal
- Physics of Interfaces and Nanomaterials, MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE, Enschede, Netherlands
| | - Kai Sotthewes
- Physics of Interfaces and Nanomaterials, MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE, Enschede, Netherlands
| | - Martin H Siekman
- Physics of Interfaces and Nanomaterials, MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE, Enschede, Netherlands
| | - E Stefan Kooij
- Physics of Interfaces and Nanomaterials, MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE, Enschede, Netherlands
| | - Harold J W Zandvliet
- Physics of Interfaces and Nanomaterials, MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE, Enschede, Netherlands
| |
Collapse
|
22
|
Moreno-García P, La Rosa A, Kolivoška V, Bermejo D, Hong W, Yoshida K, Baghernejad M, Filippone S, Broekmann P, Wandlowski T, Martín N. Charge Transport in C60-Based Dumbbell-type Molecules: Mechanically Induced Switching between Two Distinct Conductance States. J Am Chem Soc 2015; 137:2318-27. [DOI: 10.1021/ja511271e] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Pavel Moreno-García
- Department
of Chemistry and Biochemistry, University of Bern, Freiestrasse
3, CH-3012 Bern, Switzerland
| | - Andrea La Rosa
- Departamento
de Química Orgánica, Facultad de Química, Universidad Complutense de Madrid, E-28040, Madrid, Spain
| | - Viliam Kolivoška
- Department
of Chemistry and Biochemistry, University of Bern, Freiestrasse
3, CH-3012 Bern, Switzerland
- J. Heyrovský
Institute of Physical Chemistry, AS CR, v.v.i., Dolejškova
3, 18223, Prague
8, Czech Republic
| | - Daniel Bermejo
- Departamento
de Química Orgánica, Facultad de Química, Universidad Complutense de Madrid, E-28040, Madrid, Spain
| | - Wenjing Hong
- Department
of Chemistry and Biochemistry, University of Bern, Freiestrasse
3, CH-3012 Bern, Switzerland
| | - Koji Yoshida
- Department
of Chemistry and Biochemistry, University of Bern, Freiestrasse
3, CH-3012 Bern, Switzerland
| | - Masoud Baghernejad
- Department
of Chemistry and Biochemistry, University of Bern, Freiestrasse
3, CH-3012 Bern, Switzerland
| | - Salvatore Filippone
- Departamento
de Química Orgánica, Facultad de Química, Universidad Complutense de Madrid, E-28040, Madrid, Spain
| | - Peter Broekmann
- Department
of Chemistry and Biochemistry, University of Bern, Freiestrasse
3, CH-3012 Bern, Switzerland
| | - Thomas Wandlowski
- Department
of Chemistry and Biochemistry, University of Bern, Freiestrasse
3, CH-3012 Bern, Switzerland
| | - Nazario Martín
- Departamento
de Química Orgánica, Facultad de Química, Universidad Complutense de Madrid, E-28040, Madrid, Spain
- IMDEA-Nanoscience, Campus Universidad Autónoma, 28049-Madrid, Spain
| |
Collapse
|
23
|
Schneider NL, Néel N, Andersen NP, Lü JT, Brandbyge M, Kröger J, Berndt R. Spectroscopy of transmission resonances through a C₆₀ junction. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2015; 27:015001. [PMID: 25407046 DOI: 10.1088/0953-8984/27/1/015001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Electron transport through a single C60 molecule on Cu(1 1 1) has been investigated with a scanning tunnelling microscope in tunnelling and contact ranges. Single-C60 junctions have been fabricated by establishing a contact between the molecule and the tip, which is reflected by a down-shift in the lowest unoccupied molecular orbital resonance. These junctions are stable even at elevated bias voltages enabling conductance measurements at high voltages and nonlinear conductance spectroscopy in tunnelling and contact ranges. Spectroscopy and first principles transport calculations clarify the relation between molecular orbital resonances and the junction conductance. Due to the strong molecule-electrode coupling the simple picture of electron transport through individual orbitals does not hold.
Collapse
Affiliation(s)
- N L Schneider
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, D-24098 Kiel, Germany
| | | | | | | | | | | | | |
Collapse
|
24
|
Leary E, La Rosa A, González MT, Rubio-Bollinger G, Agraït N, Martín N. Incorporating single molecules into electrical circuits. The role of the chemical anchoring group. Chem Soc Rev 2015; 44:920-42. [DOI: 10.1039/c4cs00264d] [Citation(s) in RCA: 134] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Constructing electronic circuits containing singly wired molecules is at the frontier of electrical device miniaturisation. Understanding the behaviour of different anchoring groups is key to this goal because of their significant role in determining the properties of the junction.
Collapse
Affiliation(s)
- Edmund Leary
- IMDEA Nanociencia
- C/Faraday 9
- 28049 Madrid
- Spain
- Depto. Física de la Materia Condensada Mod. 3-610 – Universidad Autónoma de Madrid
| | - Andrea La Rosa
- Departamento de Química Orgánica
- Facultad de Ciencias Quıímicas
- Universidad Complutense de Madrid
- Madrid
- Spain
| | | | - Gabino Rubio-Bollinger
- Depto. Física de la Materia Condensada Mod. 3-610 – Universidad Autónoma de Madrid
- 28049 Madrid
- Spain
| | - Nicolás Agraït
- IMDEA Nanociencia
- C/Faraday 9
- 28049 Madrid
- Spain
- Depto. Física de la Materia Condensada Mod. 3-610 – Universidad Autónoma de Madrid
| | - Nazario Martín
- IMDEA Nanociencia
- C/Faraday 9
- 28049 Madrid
- Spain
- Departamento de Química Orgánica
| |
Collapse
|
25
|
Nirmalraj P, Thompson D, Molina-Ontoria A, Sousa M, Martín N, Gotsmann B, Riel H. Nanoelectrical analysis of single molecules and atomic-scale materials at the solid/liquid interface. NATURE MATERIALS 2014; 13:947-953. [PMID: 25129620 DOI: 10.1038/nmat4060] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2013] [Accepted: 07/15/2014] [Indexed: 06/03/2023]
Abstract
Evaluating the built-in functionality of nanomaterials under practical conditions is central for their proposed integration as active components in next-generation electronics. Low-dimensional materials from single atoms to molecules have been consistently resolved and manipulated under ultrahigh vacuum at low temperatures. At room temperature, atomic-scale imaging has also been performed by probing materials at the solid/liquid interface. We exploit this electrical interface to develop a robust electronic decoupling platform that provides precise information on molecular energy levels recorded using in situ scanning tunnelling microscopy/spectroscopy with high spatial and energy resolution in a high-density liquid environment. Our experimental findings, supported by ab initio electronic structure calculations and atomic-scale molecular dynamics simulations, reveal direct mapping of single-molecule structure and resonance states at the solid/liquid interface. We further extend this approach to resolve the electronic structure of graphene monolayers at atomic length scales under standard room-temperature operating conditions.
Collapse
Affiliation(s)
- Peter Nirmalraj
- IBM Research-Zurich, Säumerstrasse 4 8803 Rüschlikon, Switzerland
| | - Damien Thompson
- 1] Department of Physics and Energy, University of Limerick, Ireland [2] Materials and Surface Science Institute, University of Limerick, Ireland
| | - Agustín Molina-Ontoria
- Instituto Madrileño de Estudios Avanzados en Nanociencia (IMDEA-Nanociencia), Cantoblanco, 28049 Madrid, Spain
| | - Marilyne Sousa
- IBM Research-Zurich, Säumerstrasse 4 8803 Rüschlikon, Switzerland
| | - Nazario Martín
- Instituto Madrileño de Estudios Avanzados en Nanociencia (IMDEA-Nanociencia), Cantoblanco, 28049 Madrid, Spain
| | - Bernd Gotsmann
- IBM Research-Zurich, Säumerstrasse 4 8803 Rüschlikon, Switzerland
| | - Heike Riel
- IBM Research-Zurich, Säumerstrasse 4 8803 Rüschlikon, Switzerland
| |
Collapse
|
26
|
Géranton G, Seiler C, Bagrets A, Venkataraman L, Evers F. Transport properties of individual C60-molecules. J Chem Phys 2014; 139:234701. [PMID: 24359380 DOI: 10.1063/1.4840535] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Electrical and thermal transport properties of C60 molecules are investigated with density-functional-theory based calculations. These calculations suggest that the optimum contact geometry for an electrode terminated with a single-Au atom is through binding to one or two C-atoms of C60 with a tendency to promote the sp(2)-hybridization into an sp(3)-type one. Transport in these junctions is primarily through an unoccupied molecular orbital that is partly hybridized with the Au, which results in splitting the degeneracy of the lowest unoccupied molecular orbital triplet. The transmission through these junctions, however, cannot be modeled by a single Lorentzian resonance, as our results show evidence of quantum interference between an occupied and an unoccupied orbital. The interference results in a suppression of conductance around the Fermi energy. Our numerical findings are readily analyzed analytically within a simple two-level model.
Collapse
Affiliation(s)
- G Géranton
- Institute of Nanotechnology, Karlsruhe Institute of Technology, Campus North, D-76128 Karlsruhe, Germany
| | - C Seiler
- Institute of Nanotechnology, Karlsruhe Institute of Technology, Campus North, D-76128 Karlsruhe, Germany
| | - A Bagrets
- Institute of Nanotechnology, Karlsruhe Institute of Technology, Campus North, D-76128 Karlsruhe, Germany
| | - L Venkataraman
- Department of Applied Physics and Applied Mathematics, Columbia University, New York, New York 10027, USA
| | - F Evers
- Institute of Nanotechnology, Karlsruhe Institute of Technology, Campus North, D-76128 Karlsruhe, Germany
| |
Collapse
|
27
|
Dappe YJ, González C, Cuevas JC. Carbon tips for all-carbon single-molecule electronics. NANOSCALE 2014; 6:6953-6958. [PMID: 24838986 DOI: 10.1039/c4nr00516c] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We present here an exhaustive ab initio study of the use of carbon-based tips as electrodes in single-molecule junctions. Motivated by recent experiments, we show that carbon tips can be combined with other carbon nanostructures, such as graphene, to form all-carbon molecular junctions with molecules like benzene or C60. Our results show that the use of carbon tips can lead to relatively conductive molecular junctions. However, contrary to junctions formed with standard metals, the conductance traces recorded during the formation of the all-carbon single-molecule junctions do not exhibit clear conductance plateaus, which can be attributed to the inability of the hydrogenated carbon tips to form chemical bonds with the organic molecules. Additionally, we explore here the use of carbon tips for scanning tunneling microscopy and show that they are well suited for obtaining sample images with atomic resolution.
Collapse
Affiliation(s)
- Y J Dappe
- Service de Physique de l'Etat Condensé (CNRS URA2464), IRAMIS, CEA Saclay, 91191 Gif-Sur-Yvette, France.
| | | | | |
Collapse
|
28
|
Gillemot K, Evangeli C, Leary E, La Rosa A, González MT, Filippone S, Grace I, Rubio-Bollinger G, Ferrer J, Martín N, Lambert CJ, Agraït N. A detailed experimental and theoretical study into the properties of C60 dumbbell junctions. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2013; 9:3812-3822. [PMID: 23630169 DOI: 10.1002/smll.201300310] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2013] [Revised: 03/04/2013] [Indexed: 06/02/2023]
Abstract
A combined experimental and theoretical investigation is carried out into the electrical transport across a fullerene dumbbell one-molecule junction. The newly designed molecule comprises two C60 s connected to a fluorene backbone via cyclopropyl groups. It is wired between gold electrodes under ambient conditions by pressing the tip of a scanning tunnelling microscope (STM) onto one of the C60 groups. The STM allows us to identify a single molecule before the junction is formed through imaging, which means unambiguously that only one molecule is wired. Once lifted, the same molecule could be wired many times as it was strongly fixed to the tip, and a high conductance state close to 10(-2) G0 is found. The results also suggest that the relative conductance fluctuations are low as a result of the low mobility of the molecule. Theoretical analysis indicates that the molecule is connected directly to one electrode through the central fluorene, and that to bind it to the gold fully it has to be pushed through a layer of adsorbates naturally present in the experiment.
Collapse
Affiliation(s)
- Katalin Gillemot
- Department of Physics, Lancaster University, Lancaster, LA1 4YB, UK
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
29
|
Evangeli C, Gillemot K, Leary E, González MT, Rubio-Bollinger G, Lambert CJ, Agraït N. Engineering the thermopower of C60 molecular junctions. NANO LETTERS 2013; 13:2141-5. [PMID: 23544957 DOI: 10.1021/nl400579g] [Citation(s) in RCA: 102] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
We report the measurement of conductance and thermopower of C60 molecular junctions using a scanning tunneling microscope (STM). In contrast to previous measurements, we use the imaging capability of the STM to determine precisely the number of molecules in the junction and measure thermopower and conductance continuously and simultaneously during formation and breaking of the molecular junction, achieving a complete characterization at the single-molecule level. We find that the thermopower of C60 dimers formed by trapping a C60 on the tip and contacting an isolated C60 almost doubles with respect to that of a single C60 and is among the highest values measured to date for organic materials. Density functional theory calculations show that the thermopower and the figure of merit continue increasing with the number of C60 molecules, demonstrating the enhancement of thermoelectric preformance by manipulation of intermolecular interactions.
Collapse
Affiliation(s)
- Charalambos Evangeli
- Departamento de Física de la Materia Condensada, Universidad Autónoma de Madrid, Madrid, Spain
| | | | | | | | | | | | | |
Collapse
|
30
|
Lörtscher E, Geskin V, Gotsmann B, Fock J, Sørensen JK, Bjørnholm T, Cornil J, van der Zant HSJ, Riel H. Bonding and electronic transport properties of fullerene and fullerene derivatives in break-junction geometries. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2013; 9:209-214. [PMID: 23008229 DOI: 10.1002/smll.201201688] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2012] [Indexed: 06/01/2023]
Abstract
Fullerenes are considered anchoring groups for molecular electronics due to a large contact area and their affinity for noble metals. The conductances of fullerene-terminated molecules, however, are found to be even lower than for thiol termination. The effects of weak molecule-metal coupling and symmetry breaking are studied by transport measurements of C(60) and functionalized C(60). The results demonstrate highy efficient contacts between Au and C(60), despite of deposition from solution.
Collapse
Affiliation(s)
- Emanuel Lörtscher
- IBM Research-Zurich, Säumerstrasse 4, CH-8803 Rüschlikon, Switzerland.
| | | | | | | | | | | | | | | | | |
Collapse
|
31
|
Sek S, Breczko J, Plonska-Brzezinska ME, Wilczewska AZ, Echegoyen L. STM-based molecular junction of carbon nano-onion. Chemphyschem 2012; 14:96-100. [PMID: 23129103 DOI: 10.1002/cphc.201200624] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2012] [Indexed: 11/11/2022]
Affiliation(s)
- Slawomir Sek
- Faculty of Chemistry, University of Warsaw, Pasteura 1, 02-093 Warsaw, Poland
| | | | | | | | | |
Collapse
|
32
|
Franke KJ, Pascual JI. Effects of electron-vibration coupling in transport through single molecules. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2012; 24:394002. [PMID: 22964796 DOI: 10.1088/0953-8984/24/39/394002] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Using scanning tunneling spectroscopy, we study the transport of electrons through C(60) molecules on different metal surfaces. When electrons tunnel through a molecule, they may excite molecular vibrations. A fingerprint of these processes is a characteristic sub-structure in the differential conductance spectra of the molecular junction reflecting the onset of vibrational excitation. Although the intensity of these processes is generally weak, they become more important as the resonant character of the transport mechanism increases. The detection of single vibrational levels crucially depends on the energy level alignment and lifetimes of excited states. In the limit of large current densities, resonant electron-vibration coupling leads to an energy accumulation in the molecule, which eventually leads to its decomposition. With our experiments on C(60) we are able to depict a molecular scale picture of how electrons interact with the vibrational degrees of freedom of single molecules in different transport regimes. This understanding helps in the development of stable molecular devices, which may also carry a switchable functionality.
Collapse
Affiliation(s)
- Katharina J Franke
- Fachbereich Physik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany.
| | | |
Collapse
|
33
|
Yang H, Boudrioua O, Mayne AJ, Comtet G, Dujardin G, Kuk Y, Sonnet P, Stauffer L, Nagarajan S, Gourdon A. The paradox of an insulating contact between a chemisorbed molecule and a wide band gap semiconductor surface. Phys Chem Chem Phys 2012; 14:1700-5. [DOI: 10.1039/c2cp23104b] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
|
34
|
Yee SK, Malen JA, Majumdar A, Segalman RA. Thermoelectricity in fullerene-metal heterojunctions. NANO LETTERS 2011; 11:4089-94. [PMID: 21882860 DOI: 10.1021/nl2014839] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Thermoelectricty in heterojunctions, where a single-molecule is trapped between metal electrodes, has been used to understand transport properties at organic-inorganic interfaces. (1) The transport in these systems is highly dependent on the energy level alignment between the molecular orbitals and the Fermi level (or work function) of the metal contacts. To date, the majority of single-molecule measurements have focused on simple small molecules where transport is dominated through the highest occupied molecular orbital. (2, 3) In these systems, energy level alignment is limited by the absence of electrode materials with low Fermi levels (i.e., large work functions). Alternatively, more controllable alignment between molecular orbitals and the Fermi level can be achieved with molecules whose transport is dominated by the lowest unoccupied molecular orbital (LUMO) because of readily available metals with lower work functions. Herein, we report molecular junction thermoelectric measurements of fullerene molecules (i.e., C(60), PCBM, and C(70)) trapped between metallic electrodes (i.e., Pt, Au, Ag). Fullerene junctions demonstrate the first strongly n-type molecular thermopower corresponding to transport through the LUMO, and the highest measured magnitude of molecular thermopower to date. While the electronic conductance of fullerenes is highly variable, due to fullerene's variable bonding geometries with the electrodes, the thermopower shows predictable trends based on the alignment of the LUMO with the work function of the electrodes. Both the magnitude and trend of the thermopower suggest that heterostructuring organic and inorganic materials at the nanoscale can further enhance thermoelectric performance, therein providing a new pathway for designing thermoelectric materials.
Collapse
Affiliation(s)
- Shannon K Yee
- Department of Mechanical Engineering, University of California, Berkeley, California 94720, United States
| | | | | | | |
Collapse
|
35
|
Néel N, Kröger J, Berndt R. Two-level conductance fluctuations of a single-molecule junction. NANO LETTERS 2011; 11:3593-3596. [PMID: 21854026 DOI: 10.1021/nl201327c] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The conductance of a single-molecule junction in a low-temperature scanning tunneling microscope has been measured at nanosecond time resolution. In a transition region between tunneling and contact the conductance exhibits rapid two-level fluctuations which are attributed to different geometries of the junction. The voltage dependence of the fluctuations indicates that electrons injected into the lowest unoccupied molecular orbital may efficiently couple to molecular vibrations.
Collapse
Affiliation(s)
- N Néel
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, D-24098 Kiel, Germany.
| | | | | |
Collapse
|
36
|
Schull G, Dappe YJ, González C, Bulou H, Berndt R. Charge injection through single and double carbon bonds. NANO LETTERS 2011; 11:3142-3146. [PMID: 21761854 DOI: 10.1021/nl201185y] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The contact conductance of oriented C(60) molecules is probed with a scanning tunneling microscope as a function of the lateral position of the tip in contact to the molecular cage. Together with first principles calculations, these measurements reveal variations of the efficiency of charge injection to the fullerene molecule with the order of the contacted carbon-carbon bond.
Collapse
Affiliation(s)
- Guillaume Schull
- Institut de Physique et Chimie des Matériaux de Strasbourg, UMR 7504 (CNRS- Université de Strasbourg ), 67034 Strasbourg, France.
| | | | | | | | | |
Collapse
|
37
|
Lee SU, Belosludov RV, Mizuseki H, Kawazoe Y. Electron transport characteristics of organic molecule encapsulated carbon nanotubes. NANOSCALE 2011; 3:1773-1779. [PMID: 21359303 DOI: 10.1039/c0nr00757a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
One-dimensional carbon nanotube (CNT) junctions with interesting device characteristics have been designed by encapsulating p- and n-type organic molecules into CNTs with electrophilic tetracyano-p-quinodimethane (TCNQ) and nucleophilic tetrakis(dimethylamino)ethylene (TDAE) molecules in order to explore the effect of encapsulation of organic molecules and rectifying behaviors of the designed one-dimensional CNT p-n junctions. Our results show that p- and n-type doping of CNTs and their associated charge transfer play an important role in determining the electron transport characteristics and lead to materials with unique properties, p-n junction diode, i.e. Zener-like diode. Furthermore, we show that the operational device characteristics of non-covalently doped CNT junctions originate from the distinct response of intrinsic transmission peaks of pure CNTs according to the type of dopant and the applied bias. We believe that the results give an insight into the design and implementation of various electronic logic functions based on CNTs for applications in the field of nanoelectronics.
Collapse
Affiliation(s)
- Sang Uck Lee
- Institute for Materials Research, Tohoku University, Sendai, 980-8577, Japan.
| | | | | | | |
Collapse
|
38
|
Gross L. Recent advances in submolecular resolution with scanning probe microscopy. Nat Chem 2011; 3:273-8. [DOI: 10.1038/nchem.1008] [Citation(s) in RCA: 154] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
|
39
|
Schmaus S, Bagrets A, Nahas Y, Yamada TK, Bork A, Bowen M, Beaurepaire E, Evers F, Wulfhekel W. Giant magnetoresistance through a single molecule. NATURE NANOTECHNOLOGY 2011; 6:185-9. [PMID: 21336269 DOI: 10.1038/nnano.2011.11] [Citation(s) in RCA: 129] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2010] [Accepted: 01/14/2011] [Indexed: 05/17/2023]
Abstract
Magnetoresistance is a change in the resistance of a material system caused by an applied magnetic field. Giant magnetoresistance occurs in structures containing ferromagnetic contacts separated by a metallic non-magnetic spacer, and is now the basis of read heads for hard drives and for new forms of random access memory. Using an insulator (for example, a molecular thin film) rather than a metal as the spacer gives rise to tunnelling magnetoresistance, which typically produces a larger change in resistance for a given magnetic field strength, but also yields higher resistances, which are a disadvantage for real device operation. Here, we demonstrate giant magnetoresistance across a single, non-magnetic hydrogen phthalocyanine molecule contacted by the ferromagnetic tip of a scanning tunnelling microscope. We measure the magnetoresistance to be 60% and the conductance to be 0.26G(0), where G(0) is the quantum of conductance. Theoretical analysis identifies spin-dependent hybridization of molecular and electrode orbitals as the cause of the large magnetoresistance.
Collapse
Affiliation(s)
- Stefan Schmaus
- Physikalisches Institut, Karlsruhe Institute of Technology, 76128 Karlsruhe, Germany
| | | | | | | | | | | | | | | | | |
Collapse
|
40
|
Karthäuser S. Control of molecule-based transport for future molecular devices. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2011; 23:013001. [PMID: 21406815 DOI: 10.1088/0953-8984/23/1/013001] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
In this review, possibilities to modify intentionally the electronic transport properties of metal/molecule/metal devices (MMM devices) are discussed. Here especially the influence of the metal work function, the metal-molecule interface, the molecule dipole and different tunneling mechanisms are considered. A route to evaluate the effective surface work function of metal-molecule systems is given and, based on experimental results, an exemplary estimation is performed. The electron transport across different metal-molecule interfaces is characterized by relating transmission coefficients extracted from experimentally derived molecular conductances, decay constants or tunneling barrier heights. Based on the reported results the tunneling decay constant can be assumed to be suitable to characterize intrinsic molecular electron transport properties, while the nature of the metal-molecule contacts is properly described by the transmission coefficient. A clear gradation of transmission efficiencies of metal-anchoring group combinations can be given.
Collapse
Affiliation(s)
- Silvia Karthäuser
- Institut für Festkörperforschung (IFF) and JARA-FIT, Forschungszentrum Jülich, D-52425 Jülich, Germany.
| |
Collapse
|
41
|
Swart I, Gross L, Liljeroth P. Single-molecule chemistry and physics explored by low-temperature scanning probe microscopy. Chem Commun (Camb) 2011; 47:9011-23. [DOI: 10.1039/c1cc11404b] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
42
|
Schull G, Frederiksen T, Arnau A, Sánchez-Portal D, Berndt R. Atomic-scale engineering of electrodes for single-molecule contacts. NATURE NANOTECHNOLOGY 2011; 6:23-7. [PMID: 21076405 DOI: 10.1038/nnano.2010.215] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2010] [Accepted: 10/07/2010] [Indexed: 05/22/2023]
Abstract
The transport of charge through a conducting material depends on the intrinsic ability of the material to conduct current and on the charge injection efficiency at the contacts between the conductor and the electrodes carrying current to and from the material. According to theoretical considerations, this concept remains valid down to the limit of single-molecule junctions. Exploring this limit in experiments requires atomic-scale control of the junction geometry. Here we present a method for probing the current through a single C(60) molecule while changing, one by one, the number of atoms in the electrode that are in contact with the molecule. We show quantitatively that the contact geometry has a strong influence on the conductance. We also find a crossover from a regime in which the conductance is limited by charge injection at the contact to a regime in which the conductance is limited by scattering at the molecule. Thus, the concepts of 'good' and 'bad' contacts, commonly used in macro- and mesoscopic physics, can also be applied at the molecular scale.
Collapse
Affiliation(s)
- Guillaume Schull
- Institut de Physique et Chimie des Matériaux de Strasbourg, UMR 7504 (CNRS - Université de Strasbourg), 67034 Strasbourg, France.
| | | | | | | | | |
Collapse
|
43
|
Pinzón JR, Villalta-Cerdas A, Echegoyen L. Fullerenes, Carbon Nanotubes, and Graphene for Molecular Electronics. UNIMOLECULAR AND SUPRAMOLECULAR ELECTRONICS I 2011; 312:127-74. [DOI: 10.1007/128_2011_176] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
|
44
|
Altenburg SJ, Kröger J, Wang B, Bocquet ML, Lorente N, Berndt R. Graphene on Ru(0001): contact formation and chemical reactivity on the atomic scale. PHYSICAL REVIEW LETTERS 2010; 105:236101. [PMID: 21231481 DOI: 10.1103/physrevlett.105.236101] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2010] [Indexed: 05/30/2023]
Abstract
Graphene on Ru(0001) is contacted with Au tips of a cryogenic scanning tunneling microscope. The formation and conductance of single-atom contacts vary within the moiré unit cell. Density functional calculations reveal that elastic distortions of the graphene lattice occur at contact due to a selectively enhanced chemical reactivity of C atoms at hollow sites of Ru(0001). Concomitant quantum transport calculations indicate that the graphene-Ru distance determines the conductance variations.
Collapse
Affiliation(s)
- S J Altenburg
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, D-24098 Kiel, Germany.
| | | | | | | | | | | |
Collapse
|
45
|
Lee SU, Mizuseki H, Kawazoe Y. Electron transport characteristics of one-dimensional heterojunctions with multi-nitrogen-doped capped carbon nanotubes. NANOSCALE 2010; 2:2758-2764. [PMID: 20877895 DOI: 10.1039/c0nr00411a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
We present a systematic analysis of electron transport characteristics for one-dimensional heterojunctions with two multi-nitrogen-doped (multi-N-doped) capped carbon nanotubes (CNTs) facing one another at different numbers of nitrogen atoms and conformations. Our results show that the modification of the molecular orbitals by the nitrogen dopants generates conducting channels in the designed heterojunctions inducing multi-switching behavior with sequential negative differential resistance (NDR). The NDR behavior significantly depends on the doping site and conformation of doped nitrogen atoms. Furthermore, we provide a clear interpretation for the NDR behavior by a rigid shift model of the HOMO- and LUMO-filtered energy levels in the left and right electrodes under the applied biases. We believe that our results will give an insight into the design and implementation of various electronic logic functions based on CNTs for applications in the field of nanoelectronics.
Collapse
Affiliation(s)
- Sang Uck Lee
- Institute for Materials Research, Tohoku University, Sendai, 980-8577, Japan.
| | | | | |
Collapse
|
46
|
Lü JT, Brandbyge M, Hedegård P. Blowing the fuse: Berry's phase and runaway vibrations in molecular conductors. NANO LETTERS 2010; 10:1657-63. [PMID: 20380442 DOI: 10.1021/nl904233u] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
We examine a molecular bridge connecting two metallic electrodes. We find that an electronic current passing across the bridge can cause a vibrational instability of the molecule, which ultimately can lead to a breakdown of the bridge. This instability is generated by a hitherto never considered mechanism, which surprisingly involves the quantum mechanical phase of the electronic waves, the "Berry phase". This mechanism works for highly conducting bridges, and contrary to breakdown by traditional Joule heating, this instability is deterministic and occurs at certain critical voltages. We demonstrate the new mechanism using state-of-the-art ab initio calculations on realistic molecular bridges.
Collapse
Affiliation(s)
- Jing-Tao Lü
- DTU Nanotech, Department of Micro and Nanotechnology, Technical University of Denmark, Ørsteds Plads, Building 345E, Kongens Lyngby, Denmark.
| | | | | |
Collapse
|
47
|
Wang YF, Kröger J, Berndt R, Vázquez H, Brandbyge M, Paulsson M. Atomic-scale control of electron transport through single molecules. PHYSICAL REVIEW LETTERS 2010; 104:176802. [PMID: 20482125 DOI: 10.1103/physrevlett.104.176802] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2010] [Indexed: 05/29/2023]
Abstract
Tin-phthalocyanine molecules adsorbed on Ag(111) were contacted with the tip of a cryogenic scanning tunneling microscope. Orders-of-magnitude variations of the single-molecule junction conductance were achieved by controllably dehydrogenating the molecule and by modifying the atomic structure of the surface electrode. Nonequilibrium Green's function calculations reproduce the trend of the conductance and visualize the current flow through the junction, which is guided through molecule-electrode chemical bonds.
Collapse
Affiliation(s)
- Y F Wang
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, D-24098 Kiel, Germany
| | | | | | | | | | | |
Collapse
|
48
|
Grill L. Large molecules on surfaces: deposition and intramolecular STM manipulation by directional forces. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2010; 22:084023. [PMID: 21389399 DOI: 10.1088/0953-8984/22/8/084023] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Intramolecular manipulation of single molecules on a surface with a scanning tunnelling microscope enables the controlled modification of their structure and, consequently, their physical and chemical properties. This review presents examples of intramolecular manipulation experiments with rather large molecules, driven by directional, i.e. chemical or electrostatic, forces between tip and molecule. It is shown how various regimes of forces can be explored and characterized with one and the same manipulation of a single molecule by changing the tip-surface distance. Furthermore, different deposition techniques under ultrahigh vacuum conditions are discussed because the increasing functionality of such molecules can lead to fragmentation during the heating step, making their clean deposition difficult.
Collapse
Affiliation(s)
- Leonhard Grill
- Physics Department, Freie Universität Berlin, Arnimallee 14, D-14195 Berlin, Germany. Fritz-Haber-Institut of the Max-Planck-Society, Faradayweg 4-6, 14195 Berlin, Germany
| |
Collapse
|
49
|
Berndt R, Kröger J, Néel N, Schull G. Controlled single atom and single molecule contacts. Phys Chem Chem Phys 2010; 12:1022-32. [DOI: 10.1039/b908672m] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
50
|
De Sarkar A, Ample F, Joachim C. The electronic transparency of a single CO molecule at contact. Chem Phys Lett 2010. [DOI: 10.1016/j.cplett.2009.11.020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
|