1
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Hieulle J, Garcia Fernandez C, Friedrich N, Vegliante A, Sanz S, Sánchez-Portal D, Haley MM, Casado J, Frederiksen T, Pascual JI. From Solution to Surface: Persistence of the Diradical Character of a Diindenoanthracene Derivative on a Metallic Substrate. J Phys Chem Lett 2023; 14:11506-11512. [PMID: 38088859 DOI: 10.1021/acs.jpclett.3c02401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2023]
Abstract
Organic diradicals are envisioned as elementary building blocks for designing a new generation of spintronic devices and have been used in constructing prototypical field effect transistors and nonlinear optical devices. Open-shell systems, however, are also reactive, thus requiring design strategies to "protect" their radical character from the environment, especially when they are embedded in solid-state devices. Here, we report the persistence on a metallic surface of the diradical character of a diindeno[b,i]anthracene (DIAn) core protected by bulky end-groups. Our scanning tunneling spectroscopy measurements on single-molecules detected singlet-triplet excitations that were absent for DIAn species packed in assembled structures. Density functional theory simulations unravel that the molecular geometry on the metal substrate can crucially modify the value of the singlet-triplet gap via the delocalization of the radical sites. The persistence of the diradical character over metallic substrates is a promising finding for integrating radical-based materials into functional devices.
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Affiliation(s)
| | | | | | | | - Sofia Sanz
- Donostia International Physics Center (DIPC), 20018 Donostia-San Sebastián, Spain
| | - Daniel Sánchez-Portal
- Donostia International Physics Center (DIPC), 20018 Donostia-San Sebastián, Spain
- Centro de Física de Materiales MPC (CSIC/UPV-EHU), 20018 Donostia-San Sebastián, Spain
| | - Michael M Haley
- Department of Chemistry & Biochemistry and the Materials Science Institute, University of Oregon, Eugene, Oregon 97403-1253, United States
| | - Juan Casado
- Department of Physical Chemistry, University of Malaga, Campus de Teatinos s/n, 229071 Malaga, Spain
| | - Thomas Frederiksen
- Donostia International Physics Center (DIPC), 20018 Donostia-San Sebastián, Spain
- Ikerbasque, Basque Foundation for Science, 48013 Bilbao, Spain
| | - José Ignacio Pascual
- CIC nanoGUNE-BRTA, 20018 Donostia-San Sebastián, Spain
- Ikerbasque, Basque Foundation for Science, 48013 Bilbao, Spain
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2
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Gao Y, Vlaic S, Gorni T, De' Medici L, Clair S, Roditchev D, Pons S. Manipulation of the Magnetic State of a Porphyrin-Based Molecule on Gold: From Kondo to Quantum Nanomagnet via the Charge Fluctuation Regime. ACS NANO 2023; 17:9082-9089. [PMID: 37162317 DOI: 10.1021/acsnano.2c12223] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
By moving individual Fe-porphyrin-based molecules with the tip of a scanning tunneling microscope in the vicinity of the elbow of the herringbone-reconstructed Au(111) containing a Br atom, we reversibly and continuously control their magnetic state. Several regimes are obtained experimentally and explored theoretically: from the integer spin limit, through intermediate magnetic states with renormalized magnetic anisotropy, until the Kondo-screened regime, corresponding to a progressive increase of charge fluctuations and mixed valency due to an increase in the interaction of the molecular Fe states with the substrate Fermi sea. Our study demonstrates the potential of utilizing charge fluctuations to generate and tune quantum magnetic states in molecule-surface hybrids.
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Affiliation(s)
- Yingzheng Gao
- Laboratoire de Physique et d'Étude des Matériaux (LPEM), ESPCI Paris, PSL Research University, CNRS UMR8213, Sorbonne Université, 75005 Paris, France
| | - Sergio Vlaic
- Laboratoire de Physique et d'Étude des Matériaux (LPEM), ESPCI Paris, PSL Research University, CNRS UMR8213, Sorbonne Université, 75005 Paris, France
| | - Tommaso Gorni
- Laboratoire de Physique et d'Étude des Matériaux (LPEM), ESPCI Paris, PSL Research University, CNRS UMR8213, Sorbonne Université, 75005 Paris, France
| | - Luca De' Medici
- Laboratoire de Physique et d'Étude des Matériaux (LPEM), ESPCI Paris, PSL Research University, CNRS UMR8213, Sorbonne Université, 75005 Paris, France
| | - Sylvain Clair
- Aix Marseille University, CNRS, IM2NP, 13397 Marseille, France
| | - Dimitri Roditchev
- Laboratoire de Physique et d'Étude des Matériaux (LPEM), ESPCI Paris, PSL Research University, CNRS UMR8213, Sorbonne Université, 75005 Paris, France
- Institut des Nanosciences de Paris, Sorbonne Université, CNRS UMR7588, 75005 Paris, France
| | - Stéphane Pons
- Laboratoire de Physique et d'Étude des Matériaux (LPEM), ESPCI Paris, PSL Research University, CNRS UMR8213, Sorbonne Université, 75005 Paris, France
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3
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Bhandary S, Poli E, Teobaldi G, O’Regan DD. Dynamical Screening of Local Spin Moments at Metal-Molecule Interfaces. ACS NANO 2023; 17:5974-5983. [PMID: 36881865 PMCID: PMC10062023 DOI: 10.1021/acsnano.3c00247] [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: 01/09/2023] [Accepted: 02/23/2023] [Indexed: 06/18/2023]
Abstract
Transition-metal phthalocyanine molecules have attracted considerable interest in the context of spintronics device development due to their amenability to diverse bonding regimes and their intrinsic magnetism. The latter is highly influenced by the quantum fluctuations that arise at the inevitable metal-molecule interface in a device architecture. In this study, we have systematically investigated the dynamical screening effects in phthalocyanine molecules hosting a series of transition-metal ions (Ti, V, Cr, Mn, Fe, Co, and Ni) in contact with the Cu(111) surface. Using comprehensive density functional theory plus Anderson's Impurity Model calculations, we show that the orbital-dependent hybridization and electron correlation together result in strong charge and spin fluctuations. While the instantaneous spin moments of the transition-metal ions are near atomic-like, we find that screening gives rise to considerable lowering or even quenching of these. Our results highlight the importance of quantum fluctuations in metal-contacted molecular devices, which may influence the results obtained from theoretical or experimental probes, depending on their possibly material-dependent characteristic sampling time-scales.
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Affiliation(s)
- Sumanta Bhandary
- School
of Physics and CRANN Institute, Trinity
College Dublin, The University
of Dublin, Dublin 2, Ireland
| | - Emiliano Poli
- Scientific
Computing Department, STFC UKRI, Rutherford
Appleton Laboratory, Didcot OX11 0QX, United Kingdom
| | - Gilberto Teobaldi
- Scientific
Computing Department, STFC UKRI, Rutherford
Appleton Laboratory, Didcot OX11 0QX, United Kingdom
- School
of Chemistry, University of Southampton, Highfield SO17 1BJ, Southampton, United Kingdom
| | - David D. O’Regan
- School
of Physics and CRANN Institute, Trinity
College Dublin, The University
of Dublin, Dublin 2, Ireland
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4
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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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5
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Zhang Q, Wu TC, Kuang G, Xie A, Lin N. Investigation of edge states in artificial graphene nano-flakes. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 33:225003. [PMID: 33607633 DOI: 10.1088/1361-648x/abe819] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2020] [Accepted: 02/19/2021] [Indexed: 06/12/2023]
Abstract
Graphene nano-flakes (GNFs) are predicted to host spin-polarized metallic edge states, which are envisioned for exploration of spintronics at the nanometer scale. To date, experimental realization of GNFs is only in its infancy because of the limitation of precise cutting or synthesizing methods at the nanometer scale. Here, we use low temperature scanning tunneling microscope to manipulate coronene molecules on a Cu(111) surface to build artificial triangular and hexagonal GNFs with either zigzag or armchair type of edges. We observe that an electronic state at the Dirac point emerges only in the GNFs with zigzag edges and localizes at the outmost lattice sites. The experimental results agree well with the tight-binding calculations. Our work renders an experimental confirmation of the predicated edge states of the GNFs.
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Affiliation(s)
- Qiushi Zhang
- Department of Physics, The Hong Kong University of Science and Technology, Hong Kong, People's Republic of China
- Department of Aerospace and Mechanical Engineering, University of Notre Dame, Notre Dame, IN, United States of America
| | - Tsz Chun Wu
- Department of Physics, The Hong Kong University of Science and Technology, Hong Kong, People's Republic of China
| | - Guowen Kuang
- Department of Physics, The Hong Kong University of Science and Technology, Hong Kong, People's Republic of China
| | - A'yu Xie
- Department of Physics, The Hong Kong University of Science and Technology, Hong Kong, People's Republic of China
| | - Nian Lin
- Department of Physics, The Hong Kong University of Science and Technology, Hong Kong, People's Republic of China
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6
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Zhao Y, Jiang K, Li C, Liu Y, Xu C, Zheng W, Guan D, Li Y, Zheng H, Liu C, Luo W, Jia J, Zhuang X, Wang S. Precise Control of π-Electron Magnetism in Metal-Free Porphyrins. J Am Chem Soc 2020; 142:18532-18540. [DOI: 10.1021/jacs.0c07791] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Yan Zhao
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Shenyang National Laboratory for Materials Science, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Kaiyue Jiang
- The meso-Entropy Matter Lab, School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Can Li
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Shenyang National Laboratory for Materials Science, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Yufeng Liu
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Shenyang National Laboratory for Materials Science, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Chengyang Xu
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Shenyang National Laboratory for Materials Science, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Wenna Zheng
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Shenyang National Laboratory for Materials Science, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Dandan Guan
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Shenyang National Laboratory for Materials Science, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
- Tsung-Dao Lee Institute, Shanghai Jiao Tong University, Shanghai, 200240, China
- Shanghai Research Center for Quantum Sciences, Shanghai 201315, China
| | - Yaoyi Li
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Shenyang National Laboratory for Materials Science, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
- Tsung-Dao Lee Institute, Shanghai Jiao Tong University, Shanghai, 200240, China
- Shanghai Research Center for Quantum Sciences, Shanghai 201315, China
| | - Hao Zheng
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Shenyang National Laboratory for Materials Science, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
- Tsung-Dao Lee Institute, Shanghai Jiao Tong University, Shanghai, 200240, China
- Shanghai Research Center for Quantum Sciences, Shanghai 201315, China
| | - Canhua Liu
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Shenyang National Laboratory for Materials Science, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
- Tsung-Dao Lee Institute, Shanghai Jiao Tong University, Shanghai, 200240, China
- Shanghai Research Center for Quantum Sciences, Shanghai 201315, China
| | - Weidong Luo
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Shenyang National Laboratory for Materials Science, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
- Institute of Natural Sciences, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Jinfeng Jia
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Shenyang National Laboratory for Materials Science, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
- Tsung-Dao Lee Institute, Shanghai Jiao Tong University, Shanghai, 200240, China
- Shanghai Research Center for Quantum Sciences, Shanghai 201315, China
| | - Xiaodong Zhuang
- The meso-Entropy Matter Lab, School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Shiyong Wang
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Shenyang National Laboratory for Materials Science, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
- Tsung-Dao Lee Institute, Shanghai Jiao Tong University, Shanghai, 200240, China
- Shanghai Research Center for Quantum Sciences, Shanghai 201315, China
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7
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Liu J, Gao Y, Wang T, Xue Q, Hua M, Wang Y, Huang L, Lin N. Collective Spin Manipulation in Antiferroelastic Spin-Crossover Metallo-Supramolecular Chains. ACS NANO 2020; 14:11283-11293. [PMID: 32790285 DOI: 10.1021/acsnano.0c03163] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Coupled spin-crossover complexes in supramolecular systems feature rich spin phases that can exhibit collective behaviors. Here, we report on a molecular-level exploration of the spin phase and collective spin-crossover dynamics in metallo-supramolecular chains. Using scanning tunneling microscopy, spectroscopy, and density functional theory calculations, we identify an antiferroelastic phase in the metal-organic chains, where the Ni atoms coordinated by deprotonated tetrahydroxybenzene linkers on Au(111) are at a low-spin (S = 0) or a high-spin (S = 1) state alternately along the chains. We demonstrate that the spin phase is stabilized by the combined effects of intrachain interactions and substrate commensurability. The stability of the antiferroelastic structure drives the collective spin-state switching of multiple Ni atoms in the same chain in response to electron/hole tunneling to a Ni atom via a domino-like magnetostructural relaxation process. These results provide insights into the magnetostructural dynamics of the supramolecular structures, offering a route toward their spintronic manipulations.
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Affiliation(s)
- Jing Liu
- Department of Physics, The Hong Kong University of Science and Technology, Hong Kong, China
- Division of Quantum State of Matter, Beijing Academy of Quantum Information Sciences, 100193 Beijing, China
| | - Yifan Gao
- Department of Physics, The Hong Kong University of Science and Technology, Hong Kong, China
- Department of Physics, Southern University of Science and Technology, 518055 Shenzhen, China
| | - Tong Wang
- Department of Physics, The Hong Kong University of Science and Technology, Hong Kong, China
| | - Qiang Xue
- Key Laboratory for the Physics and Chemistry of Nanodevices, Department of Electronics, Peking University, 100871 Beijing, China
| | - Muqing Hua
- Department of Physics, The Hong Kong University of Science and Technology, Hong Kong, China
| | - Yongfeng Wang
- Division of Quantum State of Matter, Beijing Academy of Quantum Information Sciences, 100193 Beijing, China
- Key Laboratory for the Physics and Chemistry of Nanodevices, Department of Electronics, Peking University, 100871 Beijing, China
| | - Li Huang
- Department of Physics, Southern University of Science and Technology, 518055 Shenzhen, China
| | - Nian Lin
- Department of Physics, The Hong Kong University of Science and Technology, Hong Kong, China
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8
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Dioxygen at Biomimetic Single Metal-Atom Sites: Stabilization or Activation? The Case of CoTPyP/Au(111). Top Catal 2020. [DOI: 10.1007/s11244-020-01333-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
AbstractBy means of a combined experimental and computational approach, we show that a 2D metal–organic framework self-assembled at the Au(111) termination is able to mimic the O2 stabilization and activation mechanisms that are typical of the biochemical environment of proteins and enzymes. 5,10,15,20-tetra(4-pyridyl)21H,23H-porphyrin cobalt(III) chloride (CoTPyP) molecules on Au(111) bind dioxygen forming a covalent bond at the Co center, yielding charge injection into the ligand by exploiting the surface trans-effect. A weakening of the O–O bond occurs, together with the development of a dipole moment, and a change in the molecule’s magnetic moment. Also the bonding geometry is similar to the biological counterpart, with the O2 molecule sitting on-top of the Co atom and the molecular axis tilted by 118°. The ligand configuration lays between the oxo- and the superoxo-species, in agreement with the observed O–O stretching frequency measured in situ at near-ambient pressure conditions.
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9
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Zhang Q, Pang R, Luo T, Van Hove MA. Controlling the Rotational Barrier of Single Porphyrin Rotors on Surfaces. J Phys Chem B 2020; 124:953-960. [PMID: 31958369 DOI: 10.1021/acs.jpcb.9b09986] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Artificial molecular machines have played an indispensable role in many chemical and biological processes in recent decades. Among all kinds of molecular machines, molecular rotor systems have attracted increasing attention. In this work, we used density functional theory (DFT) calculations to investigate the rotational behaviors of on-surface molecular rotors based on porphyrin, which is a species of molecule with wide biological and chemical compatibilities. Moreover, our comparative studies demonstrate that macrocycle metalation, supporting substrate replacement, and functional group substitutions can effectively modify the rotational barrier of porphyrin rotors. We believe that these modification methods can further guide the path to achieve highly controllable on-surface molecular rotor systems in future applications.
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Affiliation(s)
- Qiushi Zhang
- Institute of Computational and Theoretical Studies & Department of Physics , Hong Kong Baptist University , Hong Kong SAR , China.,Department of Aerospace and Mechanical Engineering , University of Notre Dame , Notre Dame 46556 , Indiana , United States
| | - Rui Pang
- International Laboratory for Quantum Functional Materials of Henan and School of Physics and Engineering , Zhengzhou University , Zhengzhou 450001 , China
| | - Tengfei Luo
- Department of Aerospace and Mechanical Engineering , University of Notre Dame , Notre Dame 46556 , Indiana , United States
| | - Michel A Van Hove
- Institute of Computational and Theoretical Studies & Department of Physics , Hong Kong Baptist University , Hong Kong SAR , China
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10
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Inose T, Tanaka D, Liu J, Kajihara M, Mishra P, Ogawa T, Komeda T. Coordination structure conversion of protonated bisporphyrinato terbium(iii) double-decker complexes and creation of a Kondo assembly by electron injection on the Au(111) surface. NANOSCALE 2018; 10:19409-19417. [PMID: 30307449 DOI: 10.1039/c8nr04630a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The first step towards the synthesis of single-molecule magnet (SMM)-based spintronics devices is the organization and manipulation of magnetic molecules on surfaces. Our previous studies on bulk crystals demonstrated that protonated porphyrinato double-decker complexes [Tb(Hoep)(oep)] (oep = 2,3,7,8,12,13,17,18-octaethylporphyrinato) are not SMMs; however, once a hydrogen is removed to produce their neutral radical forms, [Tb(oep)2], they convert to SMMs. These intriguing properties encouraged us to examine the electronic/spin properties of these complexes and their chemical conversion ability after their transfer onto a metal substrate, similar to the environment required for the practical application of SMMs. Herein, we conducted a single-molecule-scale conversion of the protonated bis(porphyrinato)terbium(iii) double-decker complex [Tb(Hoep)(oep)], whose hepta-coordinated terbium ion changes into octa-coordinated [Tb(oep)2] on detaching a hydrogen atom by scanning tunnelling microscopy. This conversion can be caused by the injection of tunnelling electrons of energy 1.5-2.5 eV. We confirmed the conversion by analysing the topographic image and the spin state of the molecule. The latter was achieved by examining the Kondo resonance, which originated from the screening of the molecular spin by the conduction electrons of the metal. The Kondo resonance was not observed for [Tb(Hoep)(oep)] but was observed for the converted species, which agrees well with a model containing the [Tb(oep)2] molecule and Kondo resonance originating from the π-electron spin of the porphyrin ligand. Even though it is not possible to provide complete evidence of the SMM properties of the transferred molecule, we have demonstrated a possible path to realize the switch-on SMM properties of a single molecule.
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Affiliation(s)
- Tomoko Inose
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 5600043, Japan
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11
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Amokrane A, Klyatskaya S, Boero M, Ruben M, Bucher JP. Role of π-Radicals in the Spin Connectivity of Clusters and Networks of Tb Double-Decker Single Molecule Magnets. ACS NANO 2017; 11:10750-10760. [PMID: 28967736 DOI: 10.1021/acsnano.7b05804] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
When single molecule magnets (SMMs) self-assemble into 2D networks on a surface, they interact via the π-electrons of their ligands. This interaction is relevant to the quantum entanglement between molecular qubits, a key issue in quantum computing. Here, we examine the role played by the unpaired radical electron in the top ligand of Tb double-decker SMMs by comparing the spectroscopic features of isolated and 2D assembled entities on surfaces. High-resolution scanning tunneling microscopy (STM) is used to evidence experimentally the Kondo resonance of the unpaired radical spins in clusters and islands and its quenching due to up-pairing at orbital overlaps. The presence or the absence of the Kondo feature in the dI/dV maps turns out to be a good measure of the lateral interaction between molecules in 2D networks. In a 2D cluster of molecules, the π-orbital lobes that are linked through the orbital overlap show paired-up electron wave function (one singly occupied molecular orbital (SOMO) with spin-up and the other with spin-down) and therefore do not experience the Kondo resonance in the experiment. As a result, small clusters built by STM-assisted manipulation of molecules show alternating Kondo features of quantum mechanical origin, from the monomer to the dimer and the trimer. On the other hand, when the TbPc2 molecular clusters grow larger and form extended domains, a geometric rearrangement occurs, leading to the quenching of the Kondo signal on one lobe out of two. The even distribution of overlapping (SOMO) lobes on the perimeter of the molecule is induced by the square symmetry of the semi-infinite lattice and clearly distinguishes the lattice from the clusters.
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Affiliation(s)
- Anis Amokrane
- Université de Strasbourg , CNRS, IPCMS UMR 7504, F-67034 Strasbourg, France
| | - Svetlana Klyatskaya
- Karlsruher Institut für Technologie , Institut für Nanotechnologie, D-76344 Eggenstein-Leopoldshafen, Germany
| | - Mauro Boero
- Université de Strasbourg , CNRS, IPCMS UMR 7504, F-67034 Strasbourg, France
| | - Mario Ruben
- Karlsruher Institut für Technologie , Institut für Nanotechnologie, D-76344 Eggenstein-Leopoldshafen, Germany
| | - Jean-Pierre Bucher
- Université de Strasbourg , CNRS, IPCMS UMR 7504, F-67034 Strasbourg, France
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12
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Kuang G, Zhang Q, Lin T, Pang R, Shi X, Xu H, Lin N. Mechanically-Controlled Reversible Spin Crossover of Single Fe-Porphyrin Molecules. ACS NANO 2017; 11:6295-6300. [PMID: 28498652 DOI: 10.1021/acsnano.7b02567] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Spin-crossover (SCO) molecules are thought to be ideal systems for molecular spintronics when SCO can be precisely controlled at the single-molecule level. This is demonstrated here in the single-molecule junctions of Fe-porphyrin formed in a scanning tunneling microscope. Experimentally, we find that the junctions feature a zero-bias resonance in molecular conductance associated with the Fe spin center. When mechanically stretching or squeezing the junctions by adjusting the tip height, the line shape of the zero-bias resonance varies reversibly. First-principles calculations reveal that widening the junction gap by 2 Å transforms the macrocyclic core hosting the Fe center from a saddle to a planar conformation. This conformational change shortens the Fe-N bonds by 3%, which changes the Fe spin state from S = 2 to S = 1.
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Affiliation(s)
- Guowen Kuang
- Department of Physics, The Hong Kong University of Science and Technology , Hong Kong, China
| | - Qiushi Zhang
- Department of Physics, The Hong Kong University of Science and Technology , Hong Kong, China
| | - Tao Lin
- Department of Physics, The Hong Kong University of Science and Technology , Hong Kong, China
| | - Rui Pang
- Department of Physics, Southern University of Science and Technology of China , Nanshan District, Shenzhen, Guangdong 518055, China
| | - Xingqiang Shi
- Department of Physics, Southern University of Science and Technology of China , Nanshan District, Shenzhen, Guangdong 518055, China
| | - Hu Xu
- Department of Physics, Southern University of Science and Technology of China , Nanshan District, Shenzhen, Guangdong 518055, China
| | - Nian Lin
- Department of Physics, The Hong Kong University of Science and Technology , Hong Kong, China
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13
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Maughan B, Zahl P, Sutter P, Monti OLA. Ensemble Control of Kondo Screening in Molecular Adsorbates. J Phys Chem Lett 2017; 8:1837-1844. [PMID: 28383923 DOI: 10.1021/acs.jpclett.7b00278] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Switching the magnetic properties of organic semiconductors on a metal surface has thus far largely been limited to molecule-by-molecule tip-induced transformations in scanned probe experiments. Here we demonstrate with molecular resolution that collective control of activated Kondo screening can be achieved in thin-films of the organic semiconductor titanyl phthalocyanine on Cu(110) to obtain tunable concentrations of Kondo impurities. Using low-temperature scanning tunneling microscopy and spectroscopy, we show that a thermally activated molecular distortion dramatically shifts surface-molecule coupling and enables ensemble-level control of Kondo screening in the interfacial spin system. This is accompanied by the formation of a temperature-dependent Abrikosov-Suhl-Kondo resonance in the local density of states of the activated molecules. This enables coverage-dependent control over activation to the Kondo screening state. Our study thus advances the versatility of molecular switching for Kondo physics and opens new avenues for scalable bottom-up tailoring of the electronic structure and magnetic texture of organic semiconductor interfaces at the nanoscale.
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Affiliation(s)
- Bret Maughan
- University of Arizona , Department of Chemistry & Biochemistry, 1306 East University Boulevard, Tucson, Arizona 85721, United States
| | - Percy Zahl
- Brookhaven National Laboratory , Center for Functional Nanomaterials, Upton, New York 11973, United States
| | - Peter Sutter
- Brookhaven National Laboratory , Center for Functional Nanomaterials, Upton, New York 11973, United States
- Department of Electrical & Computer Engineering, University of Nebraska-Lincoln , Lincoln, Nebraska 68588, United States
| | - Oliver L A Monti
- University of Arizona , Department of Chemistry & Biochemistry, 1306 East University Boulevard, Tucson, Arizona 85721, United States
- University of Arizona , Department of Physics, 1118 East Fourth Street, Tucson, Arizona 85721, United States
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Pacchioni GE, Pivetta M, Gragnaniello L, Donati F, Autès G, Yazyev OV, Rusponi S, Brune H. Two-Orbital Kondo Screening in a Self-Assembled Metal-Organic Complex. ACS NANO 2017; 11:2675-2681. [PMID: 28234448 DOI: 10.1021/acsnano.6b07431] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Iron atoms adsorbed on a Cu(111) surface and buried under polyphenyl dicarbonitrile molecules exhibit strongly spatial anisotropic Kondo features with directionally dependent Kondo temperatures and line shapes, as evidenced by scanning tunneling spectroscopy. First-principles calculations find nearly full polarization for the half-filled Fe 3dxz and 3dyz orbitals, which therefore can give rise to Kondo screening with the experimentally observed directional dependence and distinct Kondo temperatures. X-ray absorption spectroscopy and X-ray magnetic circular dichroism measurements confirm that the spin in both channels is effectively Kondo-screened. At ideal Fe coverage, these two-orbital Kondo impurities are arranged in a self-assembled honeycomb superlattice.
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Affiliation(s)
- Giulia E Pacchioni
- Institute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL) , CH-1015 Lausanne, Switzerland
| | - Marina Pivetta
- Institute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL) , CH-1015 Lausanne, Switzerland
| | - Luca Gragnaniello
- Institute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL) , CH-1015 Lausanne, Switzerland
| | - Fabio Donati
- Institute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL) , CH-1015 Lausanne, Switzerland
| | - Gabriel Autès
- Institute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL) , CH-1015 Lausanne, Switzerland
| | - Oleg V Yazyev
- Institute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL) , CH-1015 Lausanne, Switzerland
| | - Stefano Rusponi
- Institute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL) , CH-1015 Lausanne, Switzerland
| | - Harald Brune
- Institute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL) , CH-1015 Lausanne, Switzerland
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15
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Iancu V, Schouteden K, Li Z, Van Haesendonck C. Electron–phonon coupling in engineered magnetic molecules. Chem Commun (Camb) 2016; 52:11359-11362. [DOI: 10.1039/c6cc03847f] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We probe electron–phonon coupling in CoTPyP and CrTPyP synthesized magnetic molecules. Low temperatures STS reveals pronounced Kondo resonances at zero bias in both molecules and additional Kondo resonance replicas observed at higher voltages in vibrating CoTPyP molecules.
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Affiliation(s)
- Violeta Iancu
- Laboratory of Solid-State Physics and Magnetism
- KU Leuven
- BE-3001 Leuven
- Belgium
- Extreme Light Infrastructure – Nuclear Physics/Horia Hulubei National Institute for R&D in Physics and Nuclear Engineering
| | - Koen Schouteden
- Laboratory of Solid-State Physics and Magnetism
- KU Leuven
- BE-3001 Leuven
- Belgium
| | - Zhe Li
- Laboratory of Solid-State Physics and Magnetism
- KU Leuven
- BE-3001 Leuven
- Belgium
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