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Zhao M, Zhao Y, Xi Y, Xu H, Feng H, Xu X, Hao W, Zhou S, Zhao J, Dou SX, Du Y. Electric-Field-Driven Negative Differential Conductance in 2D van der Waals Ferromagnet Fe 3GeTe 2. NANO LETTERS 2021; 21:9233-9239. [PMID: 34709835 DOI: 10.1021/acs.nanolett.1c03123] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Understanding quantum tunneling principles over two-dimensional (2D) van der Waals (vdW) ferromagnets at the atomic level is essential and complementary to the fundamental study of low-dimensional strong correlated systems and is critical for the development of magnetic tunneling devices. Here, we demonstrate a local electric-field controlled negative differential conductance (NDC) in 2D vdW ferromagnet Fe3GeTe2 (FGT) by using scanning tunneling microscopy (STM). The STM reveals that NDC shows an atomic position dependence and can be precisely modulated by altering the tunneling junction. The band shift together with electric-field-driven 3d-orbital occupancy modulates the sensitive magnetic anisotropic energy (MAE) in 2D FGT and consequently leads to electric-field-tunable NDC, which is also verified by theoretical simulation. This work realizes the electric-field-driven NDC in 2D ferromagnet FGT, which paves a way to design and develop applications based on 2D vdW magnets.
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Affiliation(s)
- Mengting Zhao
- School of Physics and BUAA-UOW Joint Research Centre, Beihang University, Beijing 100191, China
- Institute for Superconducting and Electronic Materials (ISEM), Australian Institute for Innovative Materials (AIIM), University of Wollongong, Wollongong, NSW 2500, Australia
| | - Yanyan Zhao
- Key Lab of Materials Modification by Laser, Ion and Electron Beams, Dalian University of Technology, Ministry of Education, Dalian 116024, China
| | - Yilian Xi
- School of Physics and BUAA-UOW Joint Research Centre, Beihang University, Beijing 100191, China
- Institute for Superconducting and Electronic Materials (ISEM), Australian Institute for Innovative Materials (AIIM), University of Wollongong, Wollongong, NSW 2500, Australia
| | - Hang Xu
- School of Physics and BUAA-UOW Joint Research Centre, Beihang University, Beijing 100191, China
| | - Haifeng Feng
- School of Physics and BUAA-UOW Joint Research Centre, Beihang University, Beijing 100191, China
| | - Xun Xu
- School of Physics and BUAA-UOW Joint Research Centre, Beihang University, Beijing 100191, China
- Institute for Superconducting and Electronic Materials (ISEM), Australian Institute for Innovative Materials (AIIM), University of Wollongong, Wollongong, NSW 2500, Australia
| | - Weichang Hao
- School of Physics and BUAA-UOW Joint Research Centre, Beihang University, Beijing 100191, China
| | - Si Zhou
- Institute for Superconducting and Electronic Materials (ISEM), Australian Institute for Innovative Materials (AIIM), University of Wollongong, Wollongong, NSW 2500, Australia
- Key Lab of Materials Modification by Laser, Ion and Electron Beams, Dalian University of Technology, Ministry of Education, Dalian 116024, China
| | - Jijun Zhao
- Key Lab of Materials Modification by Laser, Ion and Electron Beams, Dalian University of Technology, Ministry of Education, Dalian 116024, China
| | - Shi Xue Dou
- School of Physics and BUAA-UOW Joint Research Centre, Beihang University, Beijing 100191, China
- Institute for Superconducting and Electronic Materials (ISEM), Australian Institute for Innovative Materials (AIIM), University of Wollongong, Wollongong, NSW 2500, Australia
| | - Yi Du
- School of Physics and BUAA-UOW Joint Research Centre, Beihang University, Beijing 100191, China
- Institute for Superconducting and Electronic Materials (ISEM), Australian Institute for Innovative Materials (AIIM), University of Wollongong, Wollongong, NSW 2500, Australia
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Cirera B, Gallego JM, Martínez JI, Miranda R, Écija D. Lanthanide-porphyrin species as Kondo irreversible switches through tip-induced coordination chemistry. NANOSCALE 2021; 13:8600-8606. [PMID: 33913939 PMCID: PMC8118200 DOI: 10.1039/d0nr08992c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/20/2020] [Accepted: 03/17/2021] [Indexed: 06/12/2023]
Abstract
Metallosupramolecular chemical protocols are applied to in situ design dysprosium porphyrin complexes on Au(111) by sequential deposition of 2H-4FTPP species and Dy, resulting in the production of premetallated Dy-2H-4FTPP, partially metallated Dy-1H-4FTPP and fully metallated Dy-0H-4FTPP complexes, as determined by scanning tunneling microscopy (STM) and density functional theory (DFT) calculations. A zero bias resonance is found in the Dy-2H-4FTPP species which, upon study of its spatial distribution and behavior with temperature, is assigned to a Kondo resonance resulting from an unpaired spin in the molecular backbone, featuring a Kondo temperature (TK) of ≈ 21 K. Notably, the Kondo resonance can be switched off by removing one hydrogen atom of the macrocycle through tip-induced voltage pulses with submolecular precision. The species with this Kondo resonance can be laterally manipulated illustrating the potential to assemble artificial Kondo lattices. Our study demonstrates that the pre-metallation of macrocycles by lanthanides and their controlled manipulation is a novel strategy to engineer in situ tunable Kondo nanoarchitectures, enhancing the potential of coordination chemistry for spintronics.
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Affiliation(s)
- B. Cirera
- IMDEA NanoscienceCantoblancoMadridSpain
| | - J. M. Gallego
- Instituto de Ciencia de Materiales de Madrid (ICMM-CSIC)c/Sor Juana Inés de la Cruz 328049 MadridSpain
| | - J. I. Martínez
- Instituto de Ciencia de Materiales de Madrid (ICMM-CSIC)c/Sor Juana Inés de la Cruz 328049 MadridSpain
| | - R. Miranda
- IMDEA NanoscienceCantoblancoMadridSpain
- Departamento de Física de la Materia Condensada, Universidad Autónoma de MadridCantoblancoMadridSpain
| | - D. Écija
- IMDEA NanoscienceCantoblancoMadridSpain
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Molecular molds for regularizing Kondo states at atom/metal interfaces. Nat Commun 2020; 11:2566. [PMID: 32444665 PMCID: PMC7244723 DOI: 10.1038/s41467-020-16402-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Accepted: 04/27/2020] [Indexed: 11/12/2022] Open
Abstract
Adsorption of magnetic transition metal atoms on a metal surface leads to the formation of Kondo states at the atom/metal interfaces. However, the significant influence of surrounding environment presents challenges for potential applications. In this work, we realize a novel strategy to regularize the Kondo states by moving a CoPc molecular mold on an Au(111) surface to capture the dispersed Co adatoms. The symmetric and ordered structures of the atom-mold complexes, as well as the strong dπ–π bonding between the Co adatoms and conjugated isoindole units, result in highly robust and uniform Kondo states at the Co/Au(111) interfaces. Even more remarkably, the CoPc further enables a fine tuning of Kondo states through the molecular-mold-mediated superexchange interactions between Co adatoms separated by more than 12 Å. Being highly precise, efficient and reproducible, the proposed molecular mold strategy may open a new horizon for the construction and control of nano-sized quantum devices. The surrounding environment’s influence on the Kondo states formed around an adsorbed transition metal atom are challenging potential applications. Here, the authors demonstrate, via STM and DFT+HEOM calculations, that a metal phthalocyanine molecule on an Au(111) surface enables a fine tuning of the Kondo characteristics.
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Tunable giant magnetoresistance in a single-molecule junction. Nat Commun 2019; 10:3599. [PMID: 31399599 PMCID: PMC6689026 DOI: 10.1038/s41467-019-11587-x] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Accepted: 07/09/2019] [Indexed: 11/23/2022] Open
Abstract
Controlling electronic transport through a single-molecule junction is crucial for molecular electronics or spintronics. In magnetic molecular devices, the spin degree-of-freedom can be used to this end since the magnetic properties of the magnetic ion centers fundamentally impact the transport through the molecules. Here we demonstrate that the electron pathway in a single-molecule device can be selected between two molecular orbitals by varying a magnetic field, giving rise to a tunable anisotropic magnetoresistance up to 93%. The unique tunability of the electron pathways is due to the magnetic reorientation of the transition metal center, resulting in a re-hybridization of molecular orbitals. We obtain the tunneling electron pathways by Kondo effect, which manifests either as a peak or a dip line shape. The energy changes of these spin-reorientations are remarkably low and less than one millielectronvolt. The large tunable anisotropic magnetoresistance could be used to control electronic transport in molecular spintronics. Molecular electronics or spintronics relies on manipulating the electronic transport through microscopic molecule structures. Here the authors demonstrate the selective electron pathway in single-molecule device by magnetic field which enables a tunable anisotropic magnetoresistance up to 93%.
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Gruber M, Weismann A, Berndt R. The Kondo resonance line shape in scanning tunnelling spectroscopy: instrumental aspects. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2018; 30:424001. [PMID: 30191885 DOI: 10.1088/1361-648x/aadfa3] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
In the scanning tunnelling microscope, the many-body Kondo effect leads to a zero-bias feature of the differential conductance spectra of magnetic adsorbates on surfaces. The intrinsic line shape of this Kondo resonance and its temperature dependence in principle contain valuable information. We use measurements on a molecular Kondo system, all- trans retinoic acid on Au(1 1 1), and model calculations to discuss the role of instrumental broadening. The modulation voltage used for the lock-in detection, noise on the sample voltage, and the temperature of the microscope tip are considered. These sources of broadening affect the apparent line shapes and render difficult a determination of the intrinsic line width, in particular when variable temperatures are involved.
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Affiliation(s)
- Manuel Gruber
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, D-24098 Kiel, Germany
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Pope T, Du S, Gao HJ, Hofer WA. Electronic effects and fundamental physics studied in molecular interfaces. Chem Commun (Camb) 2018; 54:5508-5517. [PMID: 29726883 DOI: 10.1039/c8cc02191k] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Scanning probe instruments in conjunction with a very low temperature environment have revolutionized the ability of building, functionalizing, and analysing two dimensional interfaces in the last twenty years. In addition, the availability of fast, reliable, and increasingly sophisticated methods to simulate the structure and dynamics of these interfaces allow us to capture even very small effects at the atomic and molecular level. In this review we shall focus largely on metal surfaces and organic molecular compounds and show that building systems from the bottom up and controlling the physical properties of such systems is no longer within the realm of the desirable, but has become day to day reality in our best laboratories.
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Affiliation(s)
- Thomas Pope
- School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne NE1 7RU, UK.
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Xiang F, Gemeinhardt A, Schneider MA. Competition between Dehydrogenative Organometallic Bonding and Covalent Coupling of an Unfunctionalized Porphyrin on Cu(111). ACS NANO 2018; 12:1203-1210. [PMID: 29336554 DOI: 10.1021/acsnano.7b06998] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We studied the formation of linked porphyrin oligomers from 5,15-diphenylporphyrin (2H-DPP) by thermal, substrate-assisted organometallic and dehydrogenation coupling on Cu(111) by scanning tunneling microscopy. In the range of 300-620 K, we find three distinct stages, at 300 K, the intact 2H-DPP molecules self-assemble into linear structures held together by van der Waals forces. Increasing the substrate temperature, self-metalation and intramolecular ring-closing reactions result in planar and isolated DPP species on the surface. By C-H cleavage, porphyrin oligomers bonded by organometallic and covalent bonds between the modified DPP are formed. The amount of covalently bonded DPP oligomers increases strongly with annealing time and temperature, and they become the dominant species at 570 K. In contrast, the number of organometallically bonded DPP oligomers increases moderately even up to 620 K, indicating that in this case the organometallic bond is no precursor of the covalent bond.
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Affiliation(s)
- Feifei Xiang
- Solid State Physics, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) , Staudtstr. 7, 91058 Erlangen, Germany
| | - Anja Gemeinhardt
- Solid State Physics, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) , Staudtstr. 7, 91058 Erlangen, Germany
| | - M Alexander Schneider
- Solid State Physics, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) , Staudtstr. 7, 91058 Erlangen, Germany
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Knaak T, Gruber M, Lindström C, Bocquet ML, Heck J, Berndt R. Ligand-Induced Energy Shift and Localization of Kondo Resonances in Cobalt-Based Complexes on Cu(111). NANO LETTERS 2017; 17:7146-7151. [PMID: 29045149 DOI: 10.1021/acs.nanolett.7b04181] [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
Magnetic sandwich complexes are of particular interest for molecular spintronics. Using scanning tunneling microscopy, we evidence the successful deposition of 1,3,5-tris(η6-borabenzene-η5-cyclopentadienylcobalt) benzene, a molecule composed of three connected magnetic sandwich units, on Cu(111). Scanning tunneling spectra reveal two distinct spatial-dependent narrow resonances close to the Fermi level for the trimer molecules as well as for molecular fragments composed of one and two magnetic units. With the help of density functional theory, these resonances are interpreted as two Kondo resonances originating from two distinct nondegenerate d-like orbitals. These Kondo resonances are found to have defined spatial extents dictated by the hybridization of the involved orbitals with that of the ligands. These results opens promising perspectives for investigating complex Kondo systems composed of several "Kondo" orbitals.
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Affiliation(s)
- Thomas Knaak
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel , Leibnizstrasse 19, 24098 Kiel, Germany
| | - Manuel Gruber
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel , Leibnizstrasse 19, 24098 Kiel, Germany
| | - Christoph Lindström
- Institut für Anorganische und Angewandte Chemie, Universität Hamburg , Martin-Luther-King-Platz 6, 20146 Hamburg, Germany
| | - Marie-Laure Bocquet
- PASTEUR, Département de Chimie, École Normale Supérieure, PSL Research University, Sorbonne Universités, UPMC Université Paris 06, CNRS , 75005 Paris, France
| | - Jürgen Heck
- Institut für Anorganische und Angewandte Chemie, Universität Hamburg , Martin-Luther-King-Platz 6, 20146 Hamburg, Germany
| | - Richard Berndt
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel , Leibnizstrasse 19, 24098 Kiel, Germany
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