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Carlotto S, Verdini A, Zamborlini G, Cojocariu I, Feyer V, Floreano L, Casarin M. A local point of view of the Cu(100) → NiTPP charge transfer at the NiTPP/Cu(100) interface. Phys Chem Chem Phys 2023; 25:26779-26786. [PMID: 37781890 DOI: 10.1039/d3cp04021f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/03/2023]
Abstract
A precise understanding, at the molecular level, of the massive substrate → adsorbate charge transfer at the NiTPP/Cu(100) interface has been gained through the application of elementary symmetry arguments to the structural determination of the NiTPP adsorption site by photoelectron diffraction (PED) measurements and Amsterdam density functional calculations of the free D4h NiTPP electronic structure. In particular, the PED analysis precisely determines that, among the diverse NiTPP chemisorption sites herein considered (fourfold hollow, atop, and bridge), the fourfold hollow one is the most favorable, with the Ni atom located at 1.93 Å from the surface and at an internuclear distance of 2.66 Å from the nearest-neighbors of the substrate. The use of elementary symmetry considerations enabled us to provide a convincing modeling of the NiTPP-Cu(100) anchoring configuration and an atomistic view of the previously revealed interfacial charge transfer through the unambiguous identification of the adsorbate π* and σ* low-lying virtual orbitals, of the substrate surface atoms, and of the linear combinations of the Cu 4s atomic orbitals involved in the substrate → adsorbate charge transfer. In addition, the same considerations revealed that the experimentally reported Ni(II) → Ni(I) reduction at the interface corresponds to the fingerprint of the chemisorption site of the NiTPP on Cu(100).
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Affiliation(s)
- Silvia Carlotto
- University of Padova, Department of Chemical Sciences, via F. Marzolo 1, 35131, Padova, Italy.
- ICMATE - CNR c/o University of Padova, Department of Chemical Sciences, via F. Marzolo 1, via F. Marzolo 1, 35131, Padova, Italy
| | - Alberto Verdini
- IOM - CNR c/o University of Perugia, Department of Physics and Geology, via A. Pascoli, 06123, Perugia, Italy
| | - Giovanni Zamborlini
- TU Dortmund University, Department of Physics, Otto-Hahn-Straβe 4, 44227 Dortmund, Germany
| | - Iulia Cojocariu
- University of Trieste, Department of Physics, Via A. Valerio 2, 34127 Trieste, Italy
- Elettra-Sincrotrone, S.C.p.A., S.S. 14 - km 163.5, 34149 Trieste, Italy
| | - Vitaliy Feyer
- Forschungszentrum Jülich GmbH, Peter Grünberg Institute (PGI-6), Leo-Brandt-Straβe, 52428 Jülich, Germany
- Duisburg-Essen University, Department of Physics and Center for Nanointegration Duisburg-Essen (CENIDE), 47048 Duisburg, Germany
| | - Luca Floreano
- CNR - IOM, Lab. TASC, Basovizza S.S. 14, km 163.5, 34149 Trieste, Italy
| | - Maurizio Casarin
- University of Padova, Department of Chemical Sciences, via F. Marzolo 1, 35131, Padova, Italy.
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2
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Chen J, Wu G, Ding Y, Chen Q, Gao W, Zhang T, Jing X, Lin H, Xue F, Tao L. Antioxidative 2D Bismuth Selenide via Halide Passivation for Enhanced Device Stability. NANOMATERIALS (BASEL, SWITZERLAND) 2023; 13:2056. [PMID: 37513067 PMCID: PMC10383381 DOI: 10.3390/nano13142056] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2023] [Revised: 07/01/2023] [Accepted: 07/06/2023] [Indexed: 07/30/2023]
Abstract
The topological insulator 2D Bi2Se3 is promising for electronic devices due to its unique electronic properties; however, it is challenging to prepare antioxidative nanosheets since Bi2Se3 is prone to oxidation. Surface passivation using ligand agents after Bi2Se3 exfoliation works well to protect the surface, but the process is time-consuming and technically challenging; a passivation agent that is stable under a highly biased potential is significant for in situ passivation of the Bi2Se3 surface. In this work, the roles of halide anions (Cl-, Br-, and I-) in respect of the chemical properties of synthetic Bi2Se3 nanosheets during electrochemical intercalated exfoliation were investigated to determine the antioxidation capacity. It was found that Bi2Se3 nanosheets prepared in a solution of tetrabutylammonium chloride (TBA+ and Cl-) have the best oxidation resistance via the surface bonding of Bi with Cl, which promotes obtaining better device stability. This work paves an avenue for adjusting the components of the electrolyte to further promote the stability of 2D Bi2Se3-nanosheet-based electronic devices.
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Affiliation(s)
- Jiayi Chen
- School of Materials Science and Engineering, Southeast University, Nanjing 211189, China
- Jiangsu Key Laboratory for Advanced Metallic Materials, Southeast University, Nanjing 211189, China
| | - Guodong Wu
- School of Materials Science and Engineering, Southeast University, Nanjing 211189, China
- Jiangsu Key Laboratory for Advanced Metallic Materials, Southeast University, Nanjing 211189, China
| | - Yamei Ding
- School of Materials Science and Engineering, Southeast University, Nanjing 211189, China
- Jiangsu Key Laboratory for Advanced Metallic Materials, Southeast University, Nanjing 211189, China
| | - Qichao Chen
- School of Materials Science and Engineering, Southeast University, Nanjing 211189, China
- Jiangsu Key Laboratory for Advanced Metallic Materials, Southeast University, Nanjing 211189, China
| | - Wenya Gao
- School of Materials Science and Engineering, Southeast University, Nanjing 211189, China
- Jiangsu Key Laboratory for Advanced Metallic Materials, Southeast University, Nanjing 211189, China
| | - Tuo Zhang
- School of Materials Science and Engineering, Southeast University, Nanjing 211189, China
- Jiangsu Key Laboratory for Advanced Metallic Materials, Southeast University, Nanjing 211189, China
| | - Xu Jing
- School of Materials Science and Engineering, Southeast University, Nanjing 211189, China
- Jiangsu Key Laboratory for Advanced Metallic Materials, Southeast University, Nanjing 211189, China
| | - Huiwen Lin
- School of Materials Science and Engineering, Southeast University, Nanjing 211189, China
- Jiangsu Key Laboratory for Advanced Metallic Materials, Southeast University, Nanjing 211189, China
| | - Feng Xue
- School of Materials Science and Engineering, Southeast University, Nanjing 211189, China
- Jiangsu Key Laboratory for Advanced Metallic Materials, Southeast University, Nanjing 211189, China
| | - Li Tao
- School of Materials Science and Engineering, Southeast University, Nanjing 211189, China
- Jiangsu Key Laboratory for Advanced Metallic Materials, Southeast University, Nanjing 211189, China
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3
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Alotibi S, Hickey BJ, Teobaldi G, Ali M, Barker J, Poli E, O'Regan DD, Ramasse Q, Burnell G, Patchett J, Ciccarelli C, Alyami M, Moorsom T, Cespedes O. Enhanced Spin-Orbit Coupling in Heavy Metals via Molecular Coupling. ACS APPLIED MATERIALS & INTERFACES 2021; 13:5228-5234. [PMID: 33470108 DOI: 10.1021/acsami.0c19403] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
5d metals are used in electronics because of their high spin-orbit coupling (SOC) leading to efficient spin-electric conversion. When C60 is grown on a metal, the electronic structure is altered due to hybridization and charge transfer. In this work, we measure the spin Hall magnetoresistance for Pt/C60 and Ta/C60, finding that they are up to a factor of 6 higher than those for pristine metals, indicating a 20-60% increase in the spin Hall angle. At low fields of 1-30 mT, the presence of C60 increased the anisotropic magnetoresistance by up to 700%. Our measurements are supported by noncollinear density functional theory calculations, which predict a significant SOC enhancement by C60 that penetrates through the Pt layer, concomitant with trends in the magnetic moment of transport electrons acquired via SOC and symmetry breaking. The charge transfer and hybridization between the metal and C60 can be controlled by gating, so our results indicate the possibility of dynamically modifying the SOC of thin metals using molecular layers. This could be exploited in spin-transfer torque memories and pure spin current circuits.
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Affiliation(s)
- Satam Alotibi
- School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, U.K
| | - Bryan J Hickey
- School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, U.K
| | - Gilberto Teobaldi
- Scientific Computing Department, Science and Technology Facilities Council, Didcot OX11 0QX, U.K
- Beijing Computational Science Research Center, Beijing 100193, China
- Stephenson Institute for Renewable Energy, Department of Chemistry, University of Liverpool, Liverpool L69 3BX, U.K
- School of Chemistry, University of Southampton, Highfield, Southampton SO17 1BJ, U.K
| | - Mannan Ali
- School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, U.K
| | - Joseph Barker
- School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, U.K
| | - Emiliano Poli
- Scientific Computing Department, Science and Technology Facilities Council, Didcot OX11 0QX, U.K
| | - David D O'Regan
- School of Physics, Trinity College Dublin, The University of Dublin, Dublin 2, Ireland
- Centre for Research on Adaptive Nanostructures and Nanodevices (CRANN) and the SFI Advanced Materials and Bio-Engineering Research Centre (AMBER), Dublin 2, Ireland
| | - Quentin Ramasse
- School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, U.K
- SuperSTEM, SciTech Daresbury Science and Innovation Campus, Keckwick Lane, Daresbury WA4 4AD, U.K
| | - Gavin Burnell
- School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, U.K
| | - James Patchett
- Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, U.K
| | - Chiara Ciccarelli
- SuperSTEM, SciTech Daresbury Science and Innovation Campus, Keckwick Lane, Daresbury WA4 4AD, U.K
| | - Mohammed Alyami
- School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, U.K
| | - Timothy Moorsom
- School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, U.K
| | - Oscar Cespedes
- School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, U.K
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4
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Lee KW, Lee CE. Surface reconstruction and band bending in hydrogen-adsorbed [Formula: see text] topological insulator. Sci Rep 2020; 10:14504. [PMID: 32879378 PMCID: PMC7468134 DOI: 10.1038/s41598-020-71398-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2020] [Accepted: 08/11/2020] [Indexed: 11/09/2022] Open
Abstract
We have investigated the effects of hydrogen adsorption on the [Formula: see text] topological insulator by using the density functional theory calculations. We found that hydrogen adsorption on the surface leads to surface reconstruction to reduce the band bending effect. Contrasting to a previous report that hydrogen adsorption transforms the single Dirac cone at the Brillouin zone center into three Dirac cones at the zone boundary, the Dirac cones at the zone center corresponding to the topological surface states were confirmed to be robust against the hydrogen adsorption and surface reconstruction. Hydrogen adsorption induces a Rashba-like spin-splitting of the topological surface state, and can introduce Rashba-like quantum well states within the bulk gap, which can be attributed to a semiconductor-like band bending at an interface.
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Affiliation(s)
- Kyu Won Lee
- Department of Physics, Korea University, Seoul, 02841 Republic of Korea
| | - Cheol Eui Lee
- Department of Physics, Korea University, Seoul, 02841 Republic of Korea
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5
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Franco-Cañellas A, Duhm S, Gerlach A, Schreiber F. Binding and electronic level alignment of π-conjugated systems on metals. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2020; 83:066501. [PMID: 32101802 DOI: 10.1088/1361-6633/ab7a42] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
We review the binding and energy level alignment of π-conjugated systems on metals, a field which during the last two decades has seen tremendous progress both in terms of experimental characterization as well as in the depth of theoretical understanding. Precise measurements of vertical adsorption distances and the electronic structure together with ab initio calculations have shown that most of the molecular systems have to be considered as intermediate cases between weak physisorption and strong chemisorption. In this regime, the subtle interplay of different effects such as covalent bonding, charge transfer, electrostatic and van der Waals interactions yields a complex situation with different adsorption mechanisms. In order to establish a better understanding of the binding and the electronic level alignment of π-conjugated molecules on metals, we provide an up-to-date overview of the literature, explain the fundamental concepts as well as the experimental techniques and discuss typical case studies. Thereby, we relate the geometric with the electronic structure in a consistent picture and cover the entire range from weak to strong coupling.
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Affiliation(s)
- Antoni Franco-Cañellas
- Institut für Angewandte Physik, Universität Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany
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6
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Cuxart MG, Valbuena MA, Robles R, Moreno C, Bonell F, Sauthier G, Imaz I, Xu H, Nistor C, Barla A, Gargiani P, Valvidares M, Maspoch D, Gambardella P, Valenzuela SO, Mugarza A. Molecular Approach for Engineering Interfacial Interactions in Magnetic/Topological Insulator Heterostructures. ACS NANO 2020; 14:6285-6294. [PMID: 32293865 DOI: 10.1021/acsnano.0c02498] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Controlling interfacial interactions in magnetic/topological insulator heterostructures is a major challenge for the emergence of novel spin-dependent electronic phenomena. As for any rational design of heterostructures that rely on proximity effects, one should ideally retain the overall properties of each component while tuning interactions at the interface. However, in most inorganic interfaces, interactions are too strong, consequently perturbing, and even quenching, both the magnetic moment and the topological surface states at each side of the interface. Here, we show that these properties can be preserved using ligand chemistry to tune the interaction of magnetic ions with the surface states. By depositing Co-based porphyrin and phthalocyanine monolayers on the surface of Bi2Te3 thin films, robust interfaces are formed that preserve undoped topological surface states as well as the pristine magnetic moment of the divalent Co ions. The selected ligands allow us to tune the interfacial hybridization within this weak interaction regime. These results, which are in stark contrast with the observed suppression of the surface state at the first quintuple layer of Bi2Se3 induced by the interaction with Co phthalocyanines, demonstrate the capability of planar metal-organic molecules to span interactions from the strong to the weak limit.
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Affiliation(s)
- Marc G Cuxart
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, 08193 Barcelona, Spain
| | - Miguel Angel Valbuena
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, 08193 Barcelona, Spain
| | - Roberto Robles
- Centro de Fı́sica de Materiales CFM/MPC (CSIC-UPV/EHU), 20018 Donostia-San Sebastián Spain
| | - César Moreno
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, 08193 Barcelona, Spain
| | - Frédéric Bonell
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, 08193 Barcelona, Spain
| | - Guillaume Sauthier
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, 08193 Barcelona, Spain
| | - Inhar Imaz
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, 08193 Barcelona, Spain
| | - Heng Xu
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, 08193 Barcelona, Spain
| | - Corneliu Nistor
- Department of Materials, ETH Zurich, Hönggerbergring 64, CH-8093 Zurich, Switzerland
| | - Alessandro Barla
- Istituto di Struttura della Materia (ISM), Consiglio Nazionale delle Ricerche (CNR), I-34149 Trieste, Italy
| | - Pierluigi Gargiani
- ALBA Synchrotron Light Source, Carretera BP 1413km 3.3, E-08290 Cerdanyola del Vallès, Spain
| | - Manuel Valvidares
- ALBA Synchrotron Light Source, Carretera BP 1413km 3.3, E-08290 Cerdanyola del Vallès, Spain
| | - Daniel Maspoch
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, 08193 Barcelona, Spain
- Institució Catalana de Recerca i Estudis Avançats (ICREA), 08070 Barcelona, Spain
| | - Pietro Gambardella
- Department of Materials, ETH Zurich, Hönggerbergring 64, CH-8093 Zurich, Switzerland
| | - Sergio O Valenzuela
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, 08193 Barcelona, Spain
- Institució Catalana de Recerca i Estudis Avançats (ICREA), 08070 Barcelona, Spain
| | - Aitor Mugarza
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, 08193 Barcelona, Spain
- Institució Catalana de Recerca i Estudis Avançats (ICREA), 08070 Barcelona, Spain
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7
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Belec B, Ferfolja K, Goršak T, Kostevšek N, Gardonio S, Fanetti M, Valant M. Inherent Surface Properties of Adsorbent-Free Ultrathin Bi 2Se 3 Topological Insulator Platelets. Sci Rep 2019; 9:19057. [PMID: 31836791 PMCID: PMC6911074 DOI: 10.1038/s41598-019-55646-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2019] [Accepted: 11/28/2019] [Indexed: 11/09/2022] Open
Abstract
We report on a hydrothermal synthesis of hexagonal ultra-thin Bi2Se3 platelets, which was performed without any organic reactants. The synthesis resulted in the particles with a surface, clean of any organic adsorbents, which was confirmed with a high-resolution transmission electron microscopy, zeta-potential measurements and thermogravimetric measurements coupled with a mass spectroscopy. Due to the absence of the adsorbed organic layer on the Bi2Se3 platelet surface, we were able to measure their inherent surface and optical properties. So far this has not been possible as it has been believed that such hexagonal Bi2Se3 platelets can only be prepared by a solvothermal synthesis, for which it was unable to avoid the organic surface layer. Here we explain the mechanism behind the successful hydrothermal synthesis and show a striking difference in zeta potential behaviour and UV-vis absorption characteristics caused by the adsorbed layer. The surface of the hydrothermally synthesized Bi2Se3 platelets was so clean to enable the occurrence of the localized surface plasmon resonance due to the bulk and topological surface electronic states.
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Affiliation(s)
- Blaž Belec
- Materials Research Laboratory, University of Nova Gorica, Vipavska 11c, 5270, Ajdovščina, Slovenia.
| | - Katja Ferfolja
- Materials Research Laboratory, University of Nova Gorica, Vipavska 11c, 5270, Ajdovščina, Slovenia
| | - Tanja Goršak
- Department for Materials Synthesis, Jožef Stefan Institute, Jamova 39, 1000, Ljubljana, Slovenia
- Jožef Stefan International Postgraduate School, Jamova 39, 1000, Ljubljana, Slovenia
| | - Nina Kostevšek
- Department for Nanostructured Materials, Jožef Stefan Institute, Jamova 39, 1000, Ljubljana, Slovenia
| | - Sandra Gardonio
- Materials Research Laboratory, University of Nova Gorica, Vipavska 11c, 5270, Ajdovščina, Slovenia
| | - Mattia Fanetti
- Materials Research Laboratory, University of Nova Gorica, Vipavska 11c, 5270, Ajdovščina, Slovenia
| | - Matjaz Valant
- Materials Research Laboratory, University of Nova Gorica, Vipavska 11c, 5270, Ajdovščina, Slovenia
- Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, 610054, Chengdu, China
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8
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9
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Stadtmüller B, Grad L, Seidel J, Haag F, Haag N, Cinchetti M, Aeschlimann M. Modification of Pb quantum well states by the adsorption of organic molecules. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2019; 31:134005. [PMID: 30625428 DOI: 10.1088/1361-648x/aafcf5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The successful implementation of nanoscale materials in next generation optoelectronic devices crucially depends on our ability to functionalize and design low dimensional materials according to the desired field of application. Recently, organic adsorbates have revealed an enormous potential to alter the occupied surface band structure of tunable materials by the formation of tailored molecule-surface bonds. Here, we extend this concept of adsorption-induced surface band structure engineering to the unoccupied part of the surface band structure. This is achieved by our comprehensive investigation of the unoccupied band structure of a lead (Pb) monolayer film on the Ag(1 1 1) surface prior and after the adsorption of one monolayer of the aromatic molecule 3,4,9,10-perylene-tetracarboxylic-dianhydride (PTCDA). Using two-photon momentum microscopy, we show that the unoccupied states of the Pb/Ag(1 1 1) bilayer system are dominated by a parabolic quantum well state (QWS) in the center of the surface Brillouin zone with Pb p[Formula: see text] orbital character and a side band with almost linear dispersion showing Pb p[Formula: see text] orbital character. After the adsorption of PTCDA, the Pb side band remains completely unaffected while the signal of the Pb QWS is fully suppressed. This adsorption induced change in the unoccupied Pb band structure coincides with an interfacial charge transfer from the Pb layer into the PTCDA molecule. We propose that this charge transfer and the correspondingly vertical (partially chemical) interaction across the PTCDA/Pb interface suppresses the existence of the QWS in the Pb layer. Our results hence unveil a new possibility to orbital selectively tune and control the entire surface band structure of low dimensional systems by the adsorption of organic molecules.
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Affiliation(s)
- Benjamin Stadtmüller
- Department of Physics and OPTIMAS Research Center, TU Kaiserslautern, Erwin-Schrödinger-Strasse 46, 67663 Kaiserslautern, Germany. Graduate School of Excellence Materials Science in Mainz, Erwin-Schrödinger-Strasse 46, 67663 Kaiserslautern, Germany
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10
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Kumar A, Banerjee K, Foster AS, Liljeroth P. Two-Dimensional Band Structure in Honeycomb Metal-Organic Frameworks. NANO LETTERS 2018; 18:5596-5602. [PMID: 30134111 PMCID: PMC6179349 DOI: 10.1021/acs.nanolett.8b02062] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/21/2018] [Revised: 08/08/2018] [Indexed: 05/31/2023]
Abstract
Two-dimensional (2D) metal-organic frameworks (MOFs) have been recently proposed as a flexible material platform for realizing exotic quantum phases including topological and anomalous quantum Hall insulators. Experimentally, direct synthesis of 2D MOFs has been essentially confined to metal substrates, where the strong interaction with the substrate masks the intrinsic electronic properties of the MOF. In addition to electronic decoupling from the underlying metal support, synthesis on weakly interacting substrates (e.g., graphene) would enable direct realization of heterostructures of 2D MOFs with inorganic 2D materials. Here, we demonstrate synthesis of 2D honeycomb MOFs on epitaxial graphene substrate. Using low-temperature scanning tunneling microscopy (STM) and atomic force microscopy (AFM) complemented by density-functional theory (DFT) calculations, we show the formation of a 2D band structure in the MOF decoupled from the substrate. These results open the experimental path toward MOF-based designer electronic materials with complex, engineered electronic structures.
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Affiliation(s)
- Avijit Kumar
- Department
of Applied Physics, Aalto University School
of Science, PO Box 15100, 00076 Aalto, Finland
| | - Kaustuv Banerjee
- Department
of Applied Physics, Aalto University School
of Science, PO Box 15100, 00076 Aalto, Finland
| | - Adam S. Foster
- Department
of Applied Physics, Aalto University School
of Science, P.O. Box 11100, 00076 Aalto, Finland
- WPI
Nano Life Science Institute (WPI-NanoLSI), Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan
- Graduate
School Materials Science in Mainz, Staudinger Weg 9, 55128 Mainz, Germany
| | - Peter Liljeroth
- Department
of Applied Physics, Aalto University School
of Science, PO Box 15100, 00076 Aalto, Finland
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11
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Multi-orbital charge transfer at highly oriented organic/metal interfaces. Nat Commun 2017; 8:335. [PMID: 28839127 PMCID: PMC5570996 DOI: 10.1038/s41467-017-00402-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2017] [Accepted: 06/22/2017] [Indexed: 11/09/2022] Open
Abstract
The molecule-substrate interaction plays a key role in charge injection organic-based devices. Charge transfer at molecule-metal interfaces strongly affects the overall physical and magnetic properties of the system, and ultimately the device performance. Here, we report theoretical and experimental evidence of a pronounced charge transfer involving nickel tetraphenyl porphyrin molecules adsorbed on Cu(100). The exceptional charge transfer leads to filling of the higher unoccupied orbitals up to LUMO+3. As a consequence of this strong interaction with the substrate, the porphyrin's macrocycle sits very close to the surface, forcing the phenyl ligands to bend upwards. Due to this adsorption configuration, scanning tunneling microscopy cannot reliably probe the states related to the macrocycle. We demonstrate that photoemission tomography can instead access the Ni-TPP macrocycle electronic states and determine the reordering and filling of the LUMOs upon adsorption, thereby confirming the remarkable charge transfer predicted by density functional theory calculations.Charge transfer at molecule-metal interfaces affects the overall physical and magnetic properties of organic-based devices, and ultimately their performance. Here, the authors report evidence of a pronounced charge transfer involving nickel tetraphenyl porphyrin molecules adsorbed on copper.
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12
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Cinchetti M, Dediu VA, Hueso LE. Activating the molecular spinterface. NATURE MATERIALS 2017; 16:507-515. [PMID: 28439116 DOI: 10.1038/nmat4902] [Citation(s) in RCA: 140] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2017] [Accepted: 03/23/2017] [Indexed: 05/19/2023]
Abstract
The miniaturization trend in the semiconductor industry has led to the understanding that interfacial properties are crucial for device behaviour. Spintronics has not been alien to this trend, and phenomena such as preferential spin tunnelling, the spin-to-charge conversion due to the Rashba-Edelstein effect and the spin-momentum locking at the surface of topological insulators have arisen mainly from emergent interfacial properties, rather than the bulk of the constituent materials. In this Perspective we explore inorganic/molecular interfaces by looking closely at both sides of the interface. We describe recent developments and discuss the interface as an ideal platform for creating new spin effects. Finally, we outline possible technologies that can be generated thanks to the unique active tunability of molecular spinterfaces.
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Affiliation(s)
- Mirko Cinchetti
- Experimentelle Physik VI, Technische Universität Dortmund, 44221 Dortmund, Germany
| | - V Alek Dediu
- Istituto per lo Studio dei Materiali Nanostrutturati CNRISMN, 40129 Bologna, Italy
| | - Luis E Hueso
- CIC nanoGUNE, 20018 San Sebastian, Spain
- IKERBASQUE, Basque Foundation for Science, 48013 Bilbao, Spain
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13
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Tu NH, Tanabe Y, Satake Y, Huynh KK, Tanigaki K. In-plane topological p-n junction in the three-dimensional topological insulator Bi 2-xSb xTe 3-ySe y. Nat Commun 2016; 7:13763. [PMID: 27934857 PMCID: PMC5155151 DOI: 10.1038/ncomms13763] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2016] [Accepted: 10/31/2016] [Indexed: 11/14/2022] Open
Abstract
A topological p-n junction (TPNJ) is an important concept to control spin and charge transport on a surface of three-dimensional topological insulators (3D-TIs). Here we report successful fabrication of such TPNJ on a surface of 3D-TI Bi2−xSbxTe3−ySey thin films and experimental observation of the electrical transport. By tuning the chemical potential of n-type topological Dirac surface of Bi2−xSbxTe3−ySey on its top half by using tetrafluoro-7,7,8,8-tetracyanoquinodimethane as an organic acceptor molecule, a half surface can be converted to p-type with leaving the other half side as the opposite n-type, and consequently TPNJ can be created. By sweeping the back-gate voltage in the field effect transistor structure, the TPNJ was controlled both on the bottom and the top surfaces. A dramatic change in electrical transport observed at the TPNJ on 3D-TI thin films promises novel spin and charge transport of 3D-TIs for future spintronics.
Dirac cone surface states rectify an ultralow dissipative spin and charge current, but it is yet to be confirmed in devices. Here, Tu et al. observe p-type electrical transport on one half surface and n-type on the other in Bi2−xSbxTe3−ySey thin films, realizing a topological p-n junction.
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Affiliation(s)
- Ngoc Han Tu
- Department of Physics, Graduate School of Science, Tohoku University, 6-3 Aramaki, Aoba-ku, Sendai, Miyagi 980-8577, Japan
| | - Yoichi Tanabe
- Department of Physics, Graduate School of Science, Tohoku University, 6-3 Aramaki, Aoba-ku, Sendai, Miyagi 980-8577, Japan
| | - Yosuke Satake
- Department of Physics, Graduate School of Science, Tohoku University, 6-3 Aramaki, Aoba-ku, Sendai, Miyagi 980-8577, Japan
| | - Khuong Kim Huynh
- WPI-Advanced Institute for Materials Research, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8578, Japan
| | - Katsumi Tanigaki
- Department of Physics, Graduate School of Science, Tohoku University, 6-3 Aramaki, Aoba-ku, Sendai, Miyagi 980-8577, Japan.,WPI-Advanced Institute for Materials Research, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8578, Japan
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14
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Sessi P, Bathon T, Kokh KA, Tereshchenko OE, Bode M. Single Electron Gating of Topological Insulators. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2016; 28:10073-10078. [PMID: 27677534 DOI: 10.1002/adma.201602413] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2016] [Revised: 08/01/2016] [Indexed: 06/06/2023]
Abstract
The effective gating of topological insulators is demonstrated, through the coupling of molecules to their surface. By using electric fields, they allow for dynamic control of the interface charge state by adding or removing single electrons. This process creates a robust transconductance bistability resembling a single-electron transistor. These findings make hybrid molecule/topological interfaces functional elements while at the same time pushing miniaturization to its ultimate limit.
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Affiliation(s)
- Paolo Sessi
- Physikalisches Institut, Experimentelle Physik II, Universität Würzburg Am Hubland, 97074, Würzburg, Germany
| | - Thomas Bathon
- Physikalisches Institut, Experimentelle Physik II, Universität Würzburg Am Hubland, 97074, Würzburg, Germany
| | - Konstantin Aleksandrovich Kokh
- V.S. Sobolev Institute of Geology and Mineralogy, Siberian Branch Russian Academy of Sciences, 630090, Novosibirsk, Russia
- Physics Department, Novosibirsk State University, 630090, Novosibirsk, Russia
- Saint-Petersburg State University, 198504, Saint-Petersburg, Russia
| | - Oleg Evgenievich Tereshchenko
- Physics Department, Novosibirsk State University, 630090, Novosibirsk, Russia
- Saint-Petersburg State University, 198504, Saint-Petersburg, Russia
- A.V. Rzanov Institute of Semiconductor Physics, Siberian Branch Russian Academy of Sciences, 630090, Novosibirsk, Russia
| | - Matthias Bode
- Physikalisches Institut, Experimentelle Physik II, Universität Würzburg Am Hubland, 97074, Würzburg, Germany
- Wilhelm Conrad Röntgen-Center for Complex Material Systems (RCCM), Am Hubland, 97074, Würzburg, Germany
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15
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Droghetti A, Thielen P, Rungger I, Haag N, Großmann N, Stöckl J, Stadtmüller B, Aeschlimann M, Sanvito S, Cinchetti M. Dynamic spin filtering at the Co/Alq3 interface mediated by weakly coupled second layer molecules. Nat Commun 2016; 7:12668. [PMID: 27578395 PMCID: PMC5013676 DOI: 10.1038/ncomms12668] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2016] [Accepted: 07/21/2016] [Indexed: 11/09/2022] Open
Abstract
Spin filtering at organic-metal interfaces is often determined by the details of the interaction between the organic molecules and the inorganic magnets used as electrodes. Here we demonstrate a spin-filtering mechanism based on the dynamical spin relaxation of the long-living interface states formed by the magnet and weakly physisorbed molecules. We investigate the case of Alq3 on Co and, by combining two-photon photoemission experiments with electronic structure theory, show that the observed long-time spin-dependent electron dynamics is driven by molecules in the second organic layer. The interface states formed by physisorbed molecules are not spin-split, but acquire a spin-dependent lifetime, that is the result of dynamical spin-relaxation driven by the interaction with the Co substrate. Such spin-filtering mechanism has an important role in the injection of spin-polarized carriers across the interface and their successive hopping diffusion into successive molecular layers of molecular spintronics devices.
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Affiliation(s)
- Andrea Droghetti
- School of Physics, AMBER and CRANN Institute, Trinity College, Dublin 2, Ireland.,Nano-Bio Spectroscopy Group and European Theoretical Spectroscopy Facility (ETSF), Universidad del Pais Vasco CFM, CSIC-UPV/EHU-MPC &DIPC, Avenue Tolosa 72, 20018 San Sebastian, Spain
| | - Philip Thielen
- Department of Physics and Research Center OPTIMAS, University of Kaiserslautern, Erwin-Schroedinger Strasse 46, 67663 Kaiserslautern, Germany.,Graduate School of Excellence Materials Science in Mainz, Gottlieb-Daimler-Strasse 47, 67663 Kaiserslautern, Germany
| | - Ivan Rungger
- School of Physics, AMBER and CRANN Institute, Trinity College, Dublin 2, Ireland.,National Physical Laboratory, Teddington TW11 0LW, UK
| | - Norman Haag
- Department of Physics and Research Center OPTIMAS, University of Kaiserslautern, Erwin-Schroedinger Strasse 46, 67663 Kaiserslautern, Germany
| | - Nicolas Großmann
- Department of Physics and Research Center OPTIMAS, University of Kaiserslautern, Erwin-Schroedinger Strasse 46, 67663 Kaiserslautern, Germany
| | - Johannes Stöckl
- Department of Physics and Research Center OPTIMAS, University of Kaiserslautern, Erwin-Schroedinger Strasse 46, 67663 Kaiserslautern, Germany
| | - Benjamin Stadtmüller
- Department of Physics and Research Center OPTIMAS, University of Kaiserslautern, Erwin-Schroedinger Strasse 46, 67663 Kaiserslautern, Germany.,Graduate School of Excellence Materials Science in Mainz, Gottlieb-Daimler-Strasse 47, 67663 Kaiserslautern, Germany
| | - Martin Aeschlimann
- Department of Physics and Research Center OPTIMAS, University of Kaiserslautern, Erwin-Schroedinger Strasse 46, 67663 Kaiserslautern, Germany
| | - Stefano Sanvito
- School of Physics, AMBER and CRANN Institute, Trinity College, Dublin 2, Ireland
| | - Mirko Cinchetti
- Department of Physics and Research Center OPTIMAS, University of Kaiserslautern, Erwin-Schroedinger Strasse 46, 67663 Kaiserslautern, Germany
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16
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Caputo M, Panighel M, Lisi S, Khalil L, Santo GD, Papalazarou E, Hruban A, Konczykowski M, Krusin-Elbaum L, Aliev ZS, Babanly MB, Otrokov MM, Politano A, Chulkov EV, Arnau A, Marinova V, Das PK, Fujii J, Vobornik I, Perfetti L, Mugarza A, Goldoni A, Marsi M. Manipulating the Topological Interface by Molecular Adsorbates: Adsorption of Co-Phthalocyanine on Bi2Se3. NANO LETTERS 2016; 16:3409-3414. [PMID: 27010705 DOI: 10.1021/acs.nanolett.5b02635] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Topological insulators are a promising class of materials for applications in the field of spintronics. New perspectives in this field can arise from interfacing metal-organic molecules with the topological insulator spin-momentum locked surface states, which can be perturbed enhancing or suppressing spintronics-relevant properties such as spin coherence. Here we show results from an angle-resolved photemission spectroscopy (ARPES) and scanning tunnelling microscopy (STM) study of the prototypical cobalt phthalocyanine (CoPc)/Bi2Se3 interface. We demonstrate that that the hybrid interface can act on the topological protection of the surface and bury the Dirac cone below the first quintuple layer.
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Affiliation(s)
- Marco Caputo
- Laboratoire de Physique des Solides, CNRS, Universitè Paris-Sud, Université Paris-Saclay , 91405 Orsay Cedex, France
- Laboratory Micro & Nano-Carbon, Elettra - Sincrotrone Trieste S.C.p.A., s.s.14 Km 163.5, 34149 Trieste, Italy
| | - Mirko Panighel
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and The Barcelona Institute of Science and Technology, Campus UAB, Bellaterra, 08193 Barcelona, Spain
- Laboratory Micro & Nano-Carbon, Elettra - Sincrotrone Trieste S.C.p.A., s.s.14 Km 163.5, 34149 Trieste, Italy
| | - Simone Lisi
- Dipartimento di Fisica, Università di Roma La Sapienza , Piazzale A. Moro 5, 00185 Roma, Italy
- Institut Néel, CNRS/UGA UPR2940, 25 Rue des Martyrs BP 166, 38042 Grenoble, France
| | - Lama Khalil
- Laboratoire de Physique des Solides, CNRS, Universitè Paris-Sud, Université Paris-Saclay , 91405 Orsay Cedex, France
- Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin, BP48, 91192 Gif-sur-Yvette Cedex, France
| | - Giovanni Di Santo
- Laboratory Micro & Nano-Carbon, Elettra - Sincrotrone Trieste S.C.p.A., s.s.14 Km 163.5, 34149 Trieste, Italy
| | - Evangelos Papalazarou
- Laboratoire de Physique des Solides, CNRS, Universitè Paris-Sud, Université Paris-Saclay , 91405 Orsay Cedex, France
| | - Andrzej Hruban
- Institute of Electronic Materials Technology, 01-919 Warsaw, Poland
| | - Marcin Konczykowski
- Laboratoire des Solides Irradiés, Ecole Polytechnique, CNRS, CEA, Université Paris-Saclay , 91128 Palaiseau Cedex, France
| | - Lia Krusin-Elbaum
- Department of Physics, The City College of New York, CUNY , New York, New York 10031, United States
| | - Ziya S Aliev
- Institute of Catalisys and Inorganic Chemistry, Institute of Physics, Azerbaijan National Academy of Sciences , AZ-1143, Baku, Azerbaijan
| | - Mahammad B Babanly
- Institute of Catalisys and Inorganic Chemistry, Institute of Physics, Azerbaijan National Academy of Sciences , AZ-1143, Baku, Azerbaijan
| | - Mikhail M Otrokov
- Donostia International Physics Center (DIPC), 20018 Donostia-San Sebastian, Spain
- Tomsk State University , 634050 Tomsk, Russia
| | - Antonio Politano
- Department of Physics, University of Calabria , via ponte Bucci 31/C, 87036 Rende (CS), Italy
| | - Evgueni V Chulkov
- Donostia International Physics Center (DIPC), 20018 Donostia-San Sebastian, Spain
- Department of Materials Physics, University of the Basque Country UPV/EHU , 20018 Donostia-San Sebastian, Spain
- Centro de Fı́sica de Materiales (CFM), Materials Physics Center (MPC), Centro Mixto CSIC-UPV/EHU, 20018 Donostia-San Sebastian, Spain
- Saint Petersburg State University , 198504 Saint Petersburg, Russia
| | - Andrés Arnau
- Donostia International Physics Center (DIPC), 20018 Donostia-San Sebastian, Spain
- Department of Materials Physics, University of the Basque Country UPV/EHU , 20018 Donostia-San Sebastian, Spain
- Centro de Fı́sica de Materiales (CFM), Materials Physics Center (MPC), Centro Mixto CSIC-UPV/EHU, 20018 Donostia-San Sebastian, Spain
| | - Vera Marinova
- Institute of Optical Materials and Technologies, "Acad. G. Bonchev" Str 109, Sofia, Bulgaria
| | - Pranab K Das
- Istituto Officina dei Materiali (IOM)-CNR, Laboratorio TASC, Area Science Park, s.s.14, Km 163.5, 34149 Trieste, Italy
- International Centre for Theoretical Physics, Strada Costiera 11, 34100 Trieste, Italy
| | - Jun Fujii
- Istituto Officina dei Materiali (IOM)-CNR, Laboratorio TASC, Area Science Park, s.s.14, Km 163.5, 34149 Trieste, Italy
| | - Ivana Vobornik
- Istituto Officina dei Materiali (IOM)-CNR, Laboratorio TASC, Area Science Park, s.s.14, Km 163.5, 34149 Trieste, Italy
| | - Luca Perfetti
- Laboratoire des Solides Irradiés, Ecole Polytechnique, CNRS, CEA, Université Paris-Saclay , 91128 Palaiseau Cedex, France
| | - Aitor Mugarza
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and The Barcelona Institute of Science and Technology, Campus UAB, Bellaterra, 08193 Barcelona, Spain
- ICREA - Instituciò Catalana de Recerca i Estudis Avancast, Lluis Companys 23, 08010 Barcelona, Spain
| | - Andrea Goldoni
- Laboratory Micro & Nano-Carbon, Elettra - Sincrotrone Trieste S.C.p.A., s.s.14 Km 163.5, 34149 Trieste, Italy
| | - Marino Marsi
- Laboratoire de Physique des Solides, CNRS, Universitè Paris-Sud, Université Paris-Saclay , 91405 Orsay Cedex, France
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17
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Großmann N, Magri A, Laux M, Stadtmüller B, Thielen P, Schäfer B, Fuhr O, Ruben M, Cinchetti M, Aeschlimann M. Controlled manipulation of the Co–Alq3 interface by rational design of Alq3 derivatives. Dalton Trans 2016; 45:18365-18376. [DOI: 10.1039/c6dt03183h] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Recently, research has revealed that molecules can be used to steer the local spin properties of ferromagnetic surfaces.
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Affiliation(s)
- Nicolas Großmann
- Fachbereich Physik and Research Center OPTIMAS
- Technische Universität Kaiserslautern
- 67663 Kaiserslautern
- Germany
| | - Andrea Magri
- Institut für Nanotechnologie
- Karlsruher Institut für Technologie
- 76344 Leopoldshafen-Eggenstein
- Germany
| | - Martin Laux
- Fachbereich Physik and Research Center OPTIMAS
- Technische Universität Kaiserslautern
- 67663 Kaiserslautern
- Germany
| | - Benjamin Stadtmüller
- Fachbereich Physik and Research Center OPTIMAS
- Technische Universität Kaiserslautern
- 67663 Kaiserslautern
- Germany
- Graduate School of Excellence Materials Science in Mainz
| | - Philip Thielen
- Fachbereich Physik and Research Center OPTIMAS
- Technische Universität Kaiserslautern
- 67663 Kaiserslautern
- Germany
- Graduate School of Excellence Materials Science in Mainz
| | - Bernhard Schäfer
- Institut für Nanotechnologie
- Karlsruher Institut für Technologie
- 76344 Leopoldshafen-Eggenstein
- Germany
| | - Olaf Fuhr
- Institut für Nanotechnologie
- Karlsruher Institut für Technologie
- 76344 Leopoldshafen-Eggenstein
- Germany
| | - Mario Ruben
- Institut für Nanotechnologie
- Karlsruher Institut für Technologie
- 76344 Leopoldshafen-Eggenstein
- Germany
- Institute de Physique et Chimie de Matériaux de Strasbourg (IPCMS)
| | - Mirko Cinchetti
- Experimentelle Physik VI
- Technische Universität Dortmund
- 44221 Dortmund
- Germany
| | - Martin Aeschlimann
- Fachbereich Physik and Research Center OPTIMAS
- Technische Universität Kaiserslautern
- 67663 Kaiserslautern
- Germany
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