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Sierda E, Abadia M, Brede J, Elsebach M, Bugenhagen B, Prosenc MH, Bazarnik M, Wiesendanger R. On-Surface Oligomerization of Self-Terminating Molecular Chains for the Design of Spintronic Devices. ACS NANO 2017; 11:9200-9206. [PMID: 28813591 DOI: 10.1021/acsnano.7b04194] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Molecular spintronics is currently attracting a lot of attention due to its great advantages over traditional electronics. A variety of self-assembled molecule-based devices are under development, but studies regarding the reliability of the growth process remain rare. Here, we present a method to control the length of molecular spintronic chains and to make their terminations chemically inert, thereby suppressing uncontrolled coupling to surface defects. The temperature evolution of chain formation was followed by X-ray photoelectron spectroscopy to determine optimal growth conditions. The final structures of the chains were then studied, using scanning tunneling microscopy, as a function of oligomerization conditions. We find that short chains are readily synthesized with high yields and that long chains, even exceeding 70mers, can be realized under optimized growth parameters, albeit with reduced yields.
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Affiliation(s)
- Emil Sierda
- Department of Physics, University of Hamburg , Jungiusstrasse 11, D-20355 Hamburg, Germany
- Institute of Physics, Poznan University of Technology , Piotrowo 3, 60-965 Poznań, Poland
| | - Mikel Abadia
- Centro de Física de Materiales (Consejo Superior de Investigaciones Científicas (CSIC) , Universidad del País Vasco (UPV)-Euskal Herriko Unibertsitatea (EHU)-Materials Physics Center (MPC), Paseo Manuel Lardizabal 5, 20018 San Sebastián, Spain
- Donostia International Physics Center (DIPC) , Paseo Manuel Lardizabal 4, 20018 San Sebastián, Spain
| | - Jens Brede
- Centro de Física de Materiales (Consejo Superior de Investigaciones Científicas (CSIC) , Universidad del País Vasco (UPV)-Euskal Herriko Unibertsitatea (EHU)-Materials Physics Center (MPC), Paseo Manuel Lardizabal 5, 20018 San Sebastián, Spain
- Donostia International Physics Center (DIPC) , Paseo Manuel Lardizabal 4, 20018 San Sebastián, Spain
| | - Micha Elsebach
- Department of Physics, University of Hamburg , Jungiusstrasse 11, D-20355 Hamburg, Germany
| | - Bernhard Bugenhagen
- Institute of Inorganic and Applied Chemistry, University of Hamburg , Martin-Luther-King-Platz 6, D-20146 Hamburg, Germany
| | - Marc Heinrich Prosenc
- Institute of Inorganic and Applied Chemistry, University of Hamburg , Martin-Luther-King-Platz 6, D-20146 Hamburg, Germany
- Department of Chemistry, Technical University Kaiserslautern , Erwin-Schrödinger-Str. 52, D-67663 Kaiserslautern, Germany
| | - Maciej Bazarnik
- Department of Physics, University of Hamburg , Jungiusstrasse 11, D-20355 Hamburg, Germany
- Institute of Physics, Poznan University of Technology , Piotrowo 3, 60-965 Poznań, Poland
| | - Roland Wiesendanger
- Department of Physics, University of Hamburg , Jungiusstrasse 11, D-20355 Hamburg, Germany
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Singh UR, Warmuth J, Markmann V, Wiebe J, Wiesendanger R. Structural and electronic properties of ultrathin FeSe films grown on Bi 2Se 3(0 0 0 1) studied by STM/STS. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2017; 29:025004. [PMID: 27841999 DOI: 10.1088/0953-8984/29/2/025004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We report scanning tunnelling microscopy and spectroscopy (STM/STS) studies on one and two unit cell (UC) high FeSe thin films grown on Bi2Se3(0 0 0 1). In our thin films, we find the tetragonal phase of FeSe and dumb-bell shaped defects oriented along Se-Se bond directions. In addition, we observe striped moiré patterns with a periodicity of (7.3 ± 0.1) nm generated by the mismatch between the FeSe lattice and the Bi2Se3 lattice. We could not find any signature of a superconducting gap in the tunneling spectra measured on the surface of one and two UC thick islands of FeSe down to 6.5 K. The spectra rather show an asymmetric behavior across and a finite density of states at the Fermi level (E F) resembling those taken in the normal state of bulk FeSe.
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Affiliation(s)
- Udai Raj Singh
- Department of Physics, University of Hamburg, D-20355 Hamburg, Germany
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Hanzelka P, Vonka J, Musilova V. Low conductive support for thermal insulation of a sample holder of a variable temperature scanning tunneling microscope. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2013; 84:085103. [PMID: 24007103 DOI: 10.1063/1.4817214] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
We have designed a supporting system to fix a sample holder of a scanning tunneling microscope in an UHV chamber at room temperature. The microscope will operate down to a temperature of 20 K. Low thermal conductance, high mechanical stiffness, and small dimensions are the main features of the supporting system. Three sets of four glass balls placed in vertices of a tetrahedron are used for thermal insulation based on small contact areas between the glass balls. We have analyzed the thermal conductivity of the contacts between the balls mutually and between a ball and a metallic plate while the results have been applied to the entire support. The calculation based on a simple model of the setup has been verified with some experimental measurements. In comparison with other feasible supporting structures, the designed support has the lowest thermal conductance.
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Affiliation(s)
- Pavel Hanzelka
- Institute of Scientific Instruments of the ASCR, v.v.i., Academy of Sciences of the Czech Republic, Kralovopolska 147, 612 64 Brno, Czech Republic
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Chang SH, Scarfato A, Kleeberg C, Bröring M, Hoffmann G, Wiesendanger R. Adsorption behavior of asymmetric Pd pincer complexes on a Cu(111) surface. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2010; 26:10868-10871. [PMID: 20441153 DOI: 10.1021/la100746a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
We address the adsorption of asymmetric Pd pincer complexes on a Cu(111) surface by scanning tunneling microscopy. The structural asymmetry is manifested in the observation of two chiral enantiomers. To enable an unambiguous identification of individual constituents, three closely related complexes with small modifications are investigated in parallel. Thereby, methyl substituents determine attractive molecule-molecule interaction. Depending on their distribution, dimerization and tetramerization can be observed.
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Affiliation(s)
- Shih-Hsin Chang
- Institute of Applied Physics and Microstructure Research Center Hamburg, University of Hamburg, Germany
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Lämmle K, Schwarz A, Wiesendanger R. Miniaturized transportable evaporator for molecule deposition inside cryogenic scanning probe microscopes. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2010; 81:053902. [PMID: 20515150 DOI: 10.1063/1.3428621] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Here, we present a very small evaporator unit suitable to deposit molecules onto a sample in a cryogenic environment. It can be transported in an ultrahigh vacuum system and loaded into Omicron-type cantilever stages. Thus, molecule deposition inside a low temperature force microscope is possible. The design features an insulating base plate with two embedded electrical contacts and a crucible with low power consumption, which is thermally well isolated from the surrounding. The current is supplied via a removable power clip. Details of the manufacturing process as well as the used material are described. Finally, the performance of the whole setup is demonstrated.
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Affiliation(s)
- K Lämmle
- Institute of Applied Physics and Microstructure Advanced Research Center, University of Hamburg, Jungiusstrasse 11a, Hamburg D-20355, Germany
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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.
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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
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Kuck S, Chang SH, Klöckner JP, Prosenc MH, Hoffmann G, Wiesendanger R. Steering Two-Dimensional Molecular Growth via Dipolar Interaction. Chemphyschem 2009; 10:2008-11. [DOI: 10.1002/cphc.200900281] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Brede J, Linares M, Kuck S, Schwöbel J, Scarfato A, Chang SH, Hoffmann G, Wiesendanger R, Lensen R, Kouwer PHJ, Hoogboom J, Rowan AE, Bröring M, Funk M, Stafström S, Zerbetto F, Lazzaroni R. Dynamics of molecular self-ordering in tetraphenyl porphyrin monolayers on metallic substrates. NANOTECHNOLOGY 2009; 20:275602. [PMID: 19531869 DOI: 10.1088/0957-4484/20/27/275602] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
A molecular model system of tetraphenyl porphyrins (TPP) adsorbed on metallic substrates is systematically investigated within a joint scanning tunnelling microscopy/molecular modelling approach. The molecular conformation of TPP molecules, their adsorption on a gold surface and the growth of highly ordered TPP islands are modelled with a combination of density functional theory and dynamic force field methods. The results indicate a subtle interplay between different contributions. The molecule-substrate interaction causes a bending of the porphyrin core which also determines the relative orientations of phenyl legs attached to the core. A major consequence of this is a characteristic (and energetically most favourable) arrangement of molecules within self-assembled molecular clusters; the phenyl legs of adjacent molecules are not aligned parallel to each other (often denoted as pi-pi stacking) but perpendicularly in a T-shaped arrangement. The results of the simulations are fully consistent with the scanning tunnelling microscopy observations, in terms of the symmetries of individual molecules, orientation and relative alignment of molecules in the self-assembled clusters.
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Affiliation(s)
- Jens Brede
- Institute of Applied Physics, University of Hamburg, Jungiusstrasse 9, 20355 Hamburg, Germany
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