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Cojocariu I, Perilli D, Feyer V, Jugovac M. Graphene-Molecule Hybridization at a Ferromagnetic Interface. Chemistry 2024; 30:e202400857. [PMID: 38842468 DOI: 10.1002/chem.202400857] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2024] [Revised: 06/04/2024] [Accepted: 06/05/2024] [Indexed: 06/07/2024]
Abstract
The introduction of a graphene (Gr) buffer layer between a ferromagnetic substrate and a metallorganic molecule is known to mediate the magnetic coupling between them, an effect attributed to a weak hybridization between graphene and molecule. In this paper, we present experimental evidence of this effect through a detailed investigation of the frontier electronic properties of iron phthalocyanine deposited on cobalt-supported graphene. Despite being physisorbed, the molecular adsorption on Gr/Co induces a sizeable charge transfer from graphene to the molecular macrocycle leading to the partial occupation of the LUMO and the appearance of an energetically localized hybrid state, which can be attributed to the overlap between the graphene pz state and the molecular macrocycle. Graphene is not inert either; the adsorption of the molecule induces doping and alters the Fermi velocity of both the hybrid minicone state and the Dirac cone. Similar effects are observed when the molecular periphery is decorated with fluorine atoms, known for their electron-withdrawing properties, with minimal changes in the energy alignment.
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Affiliation(s)
- Iulia Cojocariu
- Dipartimento di Fisica, Università degli Studi di Trieste, Via A. Valerio 2, 34127, Trieste, Italy
- Elettra - Sincrotrone Trieste S.C.p.A, Basovizza S.S. 14, Km 163.5, 34149, Trieste, Italy
| | - Daniele Perilli
- Dipartimento di Scienza dei Materiali, Università degli Studi di Milano-Bicocca, via R. Cozzi 55, 20125, Milano, Italy
| | - Vitaliy Feyer
- Peter Grünberg Institute (PGI-6), Forschungszentrum Jülich, Wilhelm-Johnen-Straße, 52428, Jülich, Germany
| | - Matteo Jugovac
- Elettra - Sincrotrone Trieste S.C.p.A, Basovizza S.S. 14, Km 163.5, 34149, Trieste, Italy
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2
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Blanco-Rey M, Castrillo R, Ali K, Gargiani P, Ilyn M, Gastaldo M, Paradinas M, Valbuena MA, Mugarza A, Ortega JE, Schiller F, Fernández L. The Role of Rare-Earth Atoms in the Anisotropy and Antiferromagnetic Exchange Coupling at a Hybrid Metal-Organic Interface. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2024:e2402328. [PMID: 39150001 DOI: 10.1002/smll.202402328] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2024] [Revised: 07/17/2024] [Indexed: 08/17/2024]
Abstract
Magnetic anisotropy and magnetic exchange interactions are crucial parameters that characterize the hybrid metal-organic interface, a key component of an organic spintronic device. It is shown that the incorporation of 4f RE atoms to hybrid metal-organic interfaces of CuPc/REAu2 type (RE = Gd, Ho) constitutes a feasible approach toward on-demand magnetic properties and functionalities. The GdAu2 and HoAu2 substrates differ in their magnetic anisotropy behavior. Remarkably, the HoAu2 surface promotes the inherent out-of-plane anisotropy of CuPc, owing to the match between the anisotropy axis of substrate and molecule. Furthermore, the presence of RE atoms leads to a spontaneous antiferromagnetic exchange coupling at the interface, induced by the 3d-4f superexchange interaction between the unpaired 3d electron of CuPc and the 4f electrons of the RE atoms. It is shown that 4f RE atoms with unquenched quantum orbital momentum ( L $L$ ), as it is the case of Ho, induce an anisotropic interfacial exchange coupling.
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Affiliation(s)
- María Blanco-Rey
- Departamento de Polímeros y Materiales Avanzados: Física, Química y Tecnología, Universidad del País Vasco UPV/EHU, San Sebastián, 20018, Spain
- Centro de Física de Materiales CSIC-UPV/EHU-Materials Physics Center, San Sebastián, 20018, Spain
- Donostia International Physics Center, Donostia-San Sebastián, 20018, Spain
| | - Rodrigo Castrillo
- Centro de Física de Materiales CSIC-UPV/EHU-Materials Physics Center, San Sebastián, 20018, Spain
- Donostia International Physics Center, Donostia-San Sebastián, 20018, Spain
| | - Khadiza Ali
- Centro de Física de Materiales CSIC-UPV/EHU-Materials Physics Center, San Sebastián, 20018, Spain
- Donostia International Physics Center, Donostia-San Sebastián, 20018, Spain
- Chalmers University of Technology, Göteborg, Göteborg, 412 96, Sweden
| | | | - Maxim Ilyn
- Centro de Física de Materiales CSIC-UPV/EHU-Materials Physics Center, San Sebastián, 20018, Spain
| | - Michele Gastaldo
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, Barcelona, 08193, Spain
- J. Heyrovský Institute of Physical Chemistry, Czech Academy of Sciences, Prague, 18223, Czech Republic
| | - Markos Paradinas
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, Barcelona, 08193, Spain
- Institut de Ciència de Materials de Barcelona, ICMAB-CSIC, Campus UAB, Bellaterra, 08193, Spain
| | - Miguel A Valbuena
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, Barcelona, 08193, Spain
- Instituto Madrileño de Estudios Avanzados, IMDEA Nanociencia, Madrid, 28049, Spain
| | - Aitor Mugarza
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, Barcelona, 08193, Spain
- ICREA-Institució Catalana de Recerca i Estudis Avançats, Barcelona, 08010, Spain
| | - J Enrique Ortega
- Centro de Física de Materiales CSIC-UPV/EHU-Materials Physics Center, San Sebastián, 20018, Spain
- Donostia International Physics Center, Donostia-San Sebastián, 20018, Spain
- Departamento de Física Aplicada I, Universidad del País Vasco UPV/EHU, San Sebastián, 20018, Spain
| | - Frederik Schiller
- Centro de Física de Materiales CSIC-UPV/EHU-Materials Physics Center, San Sebastián, 20018, Spain
| | - Laura Fernández
- Centro de Física de Materiales CSIC-UPV/EHU-Materials Physics Center, San Sebastián, 20018, Spain
- CIC nanoGUNE-BRTA, San Sebastián, 20018, Spain
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3
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Marino M, Molteni E, Achilli S, Onida G, Fratesi G. Ab Initio Electronic, Magnetic, and Optical Properties of Fe Phthalocyanine on Cr 2O 3(0001). Molecules 2024; 29:2889. [PMID: 38930954 PMCID: PMC11206909 DOI: 10.3390/molecules29122889] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2024] [Revised: 06/14/2024] [Accepted: 06/16/2024] [Indexed: 06/28/2024] Open
Abstract
The organic molecules adsorbed on antiferromagnetic surfaces can produce interesting interface states, characterized by charge transfer mechanisms, hybridization of molecular-substrate orbitals, as well as magnetic couplings. Here, we apply an ab initio approach to study the adsorption of Fe phthalocyanine on stoichiometric Cr2O3(0001). The molecule binds via a bidentate configuration forming bonds between two opposite imide N atoms and two protruding Cr ones, making this preferred over the various possible adsorption structures. In addition to the local modifications at these sites, the electronic structure of the molecule is weakly influenced. The magnetic structure of the surface Cr atoms shows a moderate influence of molecule adsorption, not limited to the atoms in the close proximity of the molecule. Upon optical excitation at the onset, electron density moves toward the molecule, enhancing the ground state charge transfer. We investigate this movement of charge as a mechanism at the base of light-induced modifications of the magnetic structure at the interface.
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Affiliation(s)
- Marco Marino
- ETSF and Physics Department “Aldo Pontremoli”, University of Milan, Via Celoria 16, 20133 Milan, Italy; (E.M.); (S.A.); (G.O.)
| | | | | | | | - Guido Fratesi
- ETSF and Physics Department “Aldo Pontremoli”, University of Milan, Via Celoria 16, 20133 Milan, Italy; (E.M.); (S.A.); (G.O.)
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4
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Gabarró-Riera G, Sañudo EC. Challenges for exploiting nanomagnet properties on surfaces. Commun Chem 2024; 7:99. [PMID: 38693350 PMCID: PMC11063158 DOI: 10.1038/s42004-024-01183-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2023] [Accepted: 04/17/2024] [Indexed: 05/03/2024] Open
Abstract
Molecular complexes with single-molecule magnet (SMM) or qubit properties, commonly called molecular nanomagnets, are great candidates for information storage or quantum information processing technologies. However, the implementation of molecular nanomagnets in devices for the above-mentioned applications requires controlled surface deposition and addressing the nanomagnets' properties on the surface. This Perspectives paper gives a brief overview of molecular properties on a surface relevant for magnetic molecules and how they are affected when the molecules interact with a surface; then, we focus on systems of increasing complexity, where the relevant SMMs and qubit properties have been observed for the molecules deposited on surfaces; finally, future perspectives, including possible ways of overcoming the problems encountered so far are discussed.
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Affiliation(s)
- Guillem Gabarró-Riera
- Institut de Nanociència i Nanotecnologia, Universitat de Barcelona IN2UB, C/Martí i Franqués 1-11, 08028, Barcelona, Spain
- Departament de Química Inorgànica i Orgànica, Universitat de Barcelona, C/Martí i Franqués 1-11, 08028, Barcelona, Spain
| | - E Carolina Sañudo
- Institut de Nanociència i Nanotecnologia, Universitat de Barcelona IN2UB, C/Martí i Franqués 1-11, 08028, Barcelona, Spain.
- Departament de Química Inorgànica i Orgànica, Universitat de Barcelona, C/Martí i Franqués 1-11, 08028, Barcelona, Spain.
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5
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Mukhopadhyaya A, Ali ME. Can Iron-Porphyrins Behave as Single-Molecule Magnets? J Phys Chem A 2024. [PMID: 38504619 DOI: 10.1021/acs.jpca.4c00430] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/21/2024]
Abstract
The study of magnetic properties, especially the magnetic anisotropy of iron-porphyrin complexes employing multiconfigurational methods, is quite challenging due to many strongly correlated electrons in nearly degenerate orbitals. However, a prerequisite for observing the magnetic anisotropy and slow magnetization relaxation, the zero-field splitting parameter, D, was experimentally observed decades ago for halide-based axially ligated penta-coordinate Fe(III)-porphyrins. In these complexes, the signs of D were reported mostly as positive; in a few cases, inconclusive signs of the D parameter were also mentioned. However, no ab initio calculations have been reported to shed light on this. Deciphering the electronic structure of these penta-coordinated complexes employing the complete active space self-consistent field method and N-electron valence second-order perturbation theory, we confirm the positive D values. However, a negative D value is highly desired to observe the single-molecule magnet properties without an external magnetic field, which we observed in the Fe(II)-porphyrin complexes with axial imidazole ligands instead of halide ligands. The detailed analysis of the multireference wave functions unravels the role of axial ligands in determining the sign and magnitude of the D parameters.
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Affiliation(s)
| | - Md Ehesan Ali
- Institute of Nano Science and Technology, Mohali, Punjab 140306, India
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6
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Yin X, Deng L, Ruan L, Wu Y, Luo F, Qin G, Han X, Zhang X. Recent Progress for Single-Molecule Magnets Based on Rare Earth Elements. MATERIALS (BASEL, SWITZERLAND) 2023; 16:ma16093568. [PMID: 37176451 PMCID: PMC10180339 DOI: 10.3390/ma16093568] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2023] [Revised: 04/29/2023] [Accepted: 05/04/2023] [Indexed: 05/15/2023]
Abstract
Single-molecule magnets (SMMs) have attracted much attention due to their potential applications in molecular spintronic devices. Rare earth SMMs are considered to be the most promising for application owing to their large magnetic moment and strong magnetic anisotropy. In this review, the recent progress in rare earth SMMs represented by mononuclear and dinuclear complexes is highlighted, especially for the modulation of magnetic anisotropy, effective energy barrier (Ueff) and blocking temperature (TB). The terbium- and dysprosium-based SMMs have a Ueff of 1541 cm-1 and an increased TB of 80 K. They break the boiling point temperature of liquid nitrogen. The development of the preparation technology of rare earth element SMMs is also summarized in an overview. This review has important implications and insights for the design and research of Ln-SMMs.
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Affiliation(s)
- Xiang Yin
- Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), School of Material Science and Engineering, Northeastern University, Shenyang 110819, China
| | - Li Deng
- Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), School of Material Science and Engineering, Northeastern University, Shenyang 110819, China
| | - Liuxia Ruan
- Research Center for Humanoid Sensing, Zhejiang Laboratory, Hangzhou 311100, China
| | - Yanzhao Wu
- Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), School of Material Science and Engineering, Northeastern University, Shenyang 110819, China
| | - Feifei Luo
- Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), School of Material Science and Engineering, Northeastern University, Shenyang 110819, China
| | - Gaowu Qin
- Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), School of Material Science and Engineering, Northeastern University, Shenyang 110819, China
| | - Xiaoli Han
- Taian Weiye Electromechanical Technology Co., Ltd., Taian 271000, China
| | - Xianmin Zhang
- Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), School of Material Science and Engineering, Northeastern University, Shenyang 110819, China
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7
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Magnetic molecules on surfaces: SMMs and beyond. Coord Chem Rev 2023. [DOI: 10.1016/j.ccr.2022.214858] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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8
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Rosado Piquer L, Dreiser J, Sañudo EC. Heterometallic Co-Dy SMMs grafted on iron oxide nanoparticles. Dalton Trans 2021; 50:9589-9597. [PMID: 34160526 DOI: 10.1039/d1dt01519b] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Heterometallic 3d-4f SMM [Co4Dy(OH)2(SALOH)5(chp)4(MeCN)(H2O)2] (1) has been deposited onto iron oxide nanoparticles (NPs) with an oleate self-assembled monolayer (SAM) as a surfactant. The obtained hybrid molecular-inorganic system 1-NP has been thoroughly characterized. The oleate SAM separates SMM 1 from the magnetic substrate to avoid the strong-coupling between the surface and molecule to ensure that 1 retains its magnetic properties in 1-NP. The magnetic properties of the hybrid system 1-NP have been characterized by element specific XMCD: the heterometallic SMM retains its magnetic properties on the surface of the iron oxide NPs while there is an enhancement of the magnetic properties of the NPs.
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Affiliation(s)
- Lidia Rosado Piquer
- Department of Inorganic and Organic Chemistry, Inorganic Chemistry Section, Universitat de Barcelona, Carrer Martí i Franquès 1-11, 08028 Barcelona, Spain. and Institut de Nanociència i Nanotecnologia IN2UB, Universitat de Barcelona, Carrer Martí i Franquès 1-11, 08028 Barcelona, Spain
| | - Jan Dreiser
- Swiss Light Source, Paul Scherrer Institut, Forschungsstrasse 111, 5232 Villigen PSI, Switzerland
| | - E Carolina Sañudo
- Department of Inorganic and Organic Chemistry, Inorganic Chemistry Section, Universitat de Barcelona, Carrer Martí i Franquès 1-11, 08028 Barcelona, Spain. and Institut de Nanociència i Nanotecnologia IN2UB, Universitat de Barcelona, Carrer Martí i Franquès 1-11, 08028 Barcelona, Spain
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9
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Avvisati G, Gargiani P, Mariani C, Betti MG. Tuning the Magnetic Coupling of a Molecular Spin Interface via Electron Doping. NANO LETTERS 2021; 21:666-672. [PMID: 33356332 DOI: 10.1021/acs.nanolett.0c04256] [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
Mastering the magnetic response of molecular spin interfaces by tuning the occupancy of the molecular orbitals, which carry the spin magnetic moment, can be accomplished by electron doping. We propose a viable route to control the magnetization direction and magnitude of a molecular spin network, in a graphene-mediated architecture, achieved via alkali doping of manganese phthalocyanine (MnPc) molecules assembled on cobalt intercalated under a graphene membrane. The antiparallel magnetic alignment of the MnPc molecules with the underlying Co layer can be switched to a ferromagnetic state by electron doping. Multiplet calculations unveil an enhanced magnetic state of the Mn centers with a 3/2 to 5/2 spin transition induced by alkali doping, as confirmed by the steepening of the hysteresis loops, with higher saturation magnetization values. This new molecular spin configuration can be aligned by an external field, almost independently from the hard-magnet substrate effectively behaving as a free magnetic layer.
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Affiliation(s)
- Giulia Avvisati
- Physics Department, Sapienza University of Rome, Piazzale Aldo Moro, 5 00185 Rome, Italy
| | - Pierluigi Gargiani
- ALBA Synchrotron Light Source, Carrer de la Llum, 2-26 08290 Barcelona, Spain
| | - Carlo Mariani
- Physics Department, Sapienza University of Rome, Piazzale Aldo Moro, 5 00185 Rome, Italy
| | - Maria Grazia Betti
- Physics Department, Sapienza University of Rome, Piazzale Aldo Moro, 5 00185 Rome, Italy
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10
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Calloni A, Bussetti G, Avvisati G, Jagadeesh MS, Pacilè D, Ferretti A, Varsano D, Cardoso C, Duò L, Ciccacci F, Betti MG. Empty electron states in cobalt-intercalated graphene. J Chem Phys 2020; 153:214703. [PMID: 33291906 DOI: 10.1063/5.0021814] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The dispersion of the electronic states of epitaxial graphene (Gr) depends significantly on the strength of the bonding with the underlying substrate. We report on empty electron states in cobalt-intercalated Gr grown on Ir(111), studied by angle-resolved inverse photoemission spectroscopy and x-ray absorption spectroscopy, complemented with density functional theory calculations. The weakly bonded Gr on Ir preserves the peculiar spectroscopic features of the Gr band structure, and the empty spectral densities are almost unperturbed. Upon intercalation of a Co layer, the electronic response of the interface changes, with an intermixing of the Gr π* bands and Co d states, which breaks the symmetry of π/σ states, and a downshift of the upper part of the Gr Dirac cone. Similarly, the image potential of Ir(111) is unaltered by the Gr layer, while a downward shift is induced upon Co intercalation, as unveiled by the image state energy dispersion mapped in a large region of the surface Brillouin zone.
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Affiliation(s)
- Alberto Calloni
- Dipartimento di Fisica, Politecnico di Milano, piazza Leonardo da Vinci 32, I-20133 Milano, Italy
| | - Gianlorenzo Bussetti
- Dipartimento di Fisica, Politecnico di Milano, piazza Leonardo da Vinci 32, I-20133 Milano, Italy
| | - Giulia Avvisati
- Dipartimento di Fisica, Università di Roma "La Sapienza", I-00185 Roma, Italy
| | - Madan S Jagadeesh
- Dipartimento di Fisica, Politecnico di Milano, piazza Leonardo da Vinci 32, I-20133 Milano, Italy
| | - Daniela Pacilè
- Dipartimento di Fisica, Università della Calabria, I-87036 Arcavacata di Rende (Cs), Italy
| | | | | | | | - Lamberto Duò
- Dipartimento di Fisica, Politecnico di Milano, piazza Leonardo da Vinci 32, I-20133 Milano, Italy
| | - Franco Ciccacci
- Dipartimento di Fisica, Politecnico di Milano, piazza Leonardo da Vinci 32, I-20133 Milano, Italy
| | - Maria Grazia Betti
- Dipartimento di Fisica, Università di Roma "La Sapienza", I-00185 Roma, Italy
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11
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Wang Y, Wang Z, Yang J, Li X. Precise Spin Manipulation of Single Molecule Positioning on Graphene by Coordination Chemistry. J Phys Chem Lett 2020; 11:9819-9827. [PMID: 33156628 DOI: 10.1021/acs.jpclett.0c03026] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Precise spin manipulation of single molecules is crucial for future molecular spintronics. However, it has been a formidable challenge due to the complexities of the strong molecule-substrate coupling as well as the response of the molecule to external stimulus. Here we demonstrate by density functional theory calculations that precise spin manipulation can be achieved by extra CO and NO molecules coordination to transition metal phthalocyanine (TMPc) (TM = Co, Fe, Mn) molecules deposited on metal-supported graphene; the spins of TMPc molecules are switched from S to S - 1/2 (|S - 1|) after NO (CO) coordination. With the aid of a combination of molecular orbitals (MO) theory and recently developed principal interacting spin-orbital (PISO) analysis, the impacts of NO and CO coordinations on both adsorption configuration and spin polarization of TMPc are well elucidated. We reveal the different coordination geometries that CO always coordinates axially to the TM center with a linear geometry, while NO prefers a bent geometry, which can be attributed to the competition between the σ- and π-type interactions according to the PISO analysis. Particularly, the NO-MnPc complex adopts a bent geometry deviating from the prediction by the existing Enemark-Feltham formalism. In addition, MO analysis suggests that during the CO coordination, the simultaneous existence of σ-donation and π-back-donation promotes electrons flowing from the dz2 to partially occupied dπ (dxz and dxz) orbitals with subsequent reordering of the TM d-orbitals, resulting in the spin transition of S → |S - 1|. In comparison, given that NO is regarded as NO- when it adopts a bent geometry coordinating to the TM center, the complete (CoPc) or partial (FePc and MnPc) quenching of the molecular spins caused by NO coordination is attributed to the electron transfer from TM to NO. These theoretical findings provide important insights into relevant experiments and offer an effective design strategy to realize underlying single-molecular spintronics devices integrated with two-dimensional materials.
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Affiliation(s)
- Yu Wang
- Institute for Advanced Study, Shenzhen University, Shenzhen 518060, China
| | - Zheng Wang
- Institute for Advanced Study, Shenzhen University, Shenzhen 518060, China
| | - Jinlong Yang
- Hefei National Laboratory for Physical Sciences at the Microscale and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei 230026, China
| | - Xiaoguang Li
- Institute for Advanced Study, Shenzhen University, Shenzhen 518060, China
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12
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Sierda E, Elsebach M, Wiesendanger R, Bazarnik M. Probing Weakly Hybridized Magnetic Molecules by Single-Atom Magnetometry. NANO LETTERS 2019; 19:9013-9018. [PMID: 31665608 DOI: 10.1021/acs.nanolett.9b04025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Advances in molecular spintronics rely on the in-depth characterization of the molecular building blocks in terms of their electronic and, more importantly, magnetic properties. For this purpose, inert substrates that interact only weakly with adsorbed molecules are required in order to preserve their electronic states. Here, we investigate the magnetic-field response of a single paramagnetic 5,5'-dibromosalophenatocobalt(II) (CoSal) molecule adsorbed on a weakly interacting magnetic substrate, namely, Fe-intercalated graphene (GR/Fe) grown on Ir(111), by using spin-polarized scanning tunneling microscopy and spectroscopy. We have obtained local magnetization curves, spin-dependent tunneling spectra, and spatial maps of magnetic asymmetry for a single CoSal molecule, revealing its magnetic properties and coupling to the local environment. The distinct magnetic behavior of the Co metal center is found to rely strictly on its position relative to the GR/Fe moiré structure, which determines the level of hybridization between the GR/Fe surface π-system and the molecular orbitals.
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Affiliation(s)
- Emil Sierda
- Department of Physics , University of Hamburg , Jungiusstrasse 11 , D-20355 Hamburg , Germany
- Institute of Physics , Poznan University of Technology , Piotrowo 3 , 60-965 Poznan , Poland
| | - Micha Elsebach
- Department of Physics , University of Hamburg , Jungiusstrasse 11 , D-20355 Hamburg , Germany
| | - Roland Wiesendanger
- Department of Physics , University of Hamburg , Jungiusstrasse 11 , D-20355 Hamburg , Germany
| | - Maciej Bazarnik
- Department of Physics , University of Hamburg , Jungiusstrasse 11 , D-20355 Hamburg , Germany
- Institute of Physics , Poznan University of Technology , Piotrowo 3 , 60-965 Poznan , Poland
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13
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Wang Y, Li X, Yang J. Electronic and magnetic properties of CoPc and FePc molecules on graphene: the substrate, defect, and hydrogen adsorption effects. Phys Chem Chem Phys 2019; 21:5424-5434. [PMID: 30793133 DOI: 10.1039/c8cp07091a] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Transition metal phthalocyanines (TMPcs) are particularly appealing for spintronic processing and data storage devices due to their structural simplicity and functional flexibility. To realize effective control of the spins in TMPc-based systems, it is necessary to quantify how the structural and chemical environment of the molecule affects its spin center. Herein we perform a detailed investigation of the electronic and spintronic properties of vertically stacked heterostructures formed by CoPc or FePc adsorbed on a monolayer of graphene under the influences of the gold substrate, vacancies in graphene, and extra atomic hydrogen coordination on the TMPc. By using density functional theory (DFT), we reveal that both the TMPc molecules prefer the carbon-top position on graphene, and the existence of the Au substrate enhances the stability of the adsorption, while this enhanced adsorption will not modify the molecular magnetism, keeping it the same value as in the free standing case. Moreover, with the aid of a combination of DFT and ab initio wavefunction-based calculations, our results indicate that the magnetic anisotropy of the FePc-graphene complex can be actively tuned by the Au substrate. Our calculations also show that defects in graphene including single and double vacancies can modify the magnetism of these heterostructures. In particular, the spin state of FePc can be tuned from S = 1 to S = 2 with such defect engineering. Further spin state tunability can be achieved from a hydrogenation process, with the coordination of one extra hydrogen on the Co-top site for CoPc and the pyridinic N site for FePc, respectively, tuning their spin states from S = 1/2 to S = 0 and from S = 1 to S = 2. These findings may prove to be instrumental for rational design of future molecular spintronics devices integrated with two-dimensional materials.
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Affiliation(s)
- Yu Wang
- Institute for Advanced Study, Shenzhen University, Shenzhen 518060, China.
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14
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Avvisati G, Gargiani P, Mondelli P, Presel F, Bignardi L, Baraldi A, Betti MG. Metal phthalocyanines interaction with Co mediated by a moiré graphene superlattice. J Chem Phys 2019; 150:054704. [PMID: 30736689 DOI: 10.1063/1.5080533] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The assembling of metal phthalocyanines on the rippled moiré superlattice of graphene/Ir(111) intercalated with one Co layer is driven by the site-dependent polarization field induced by the incommensurate graphene-Co interface. We have performed an X-ray absorption and photoemission study to unveil the role of the metallic centers and of the organic ligands in the molecule-Co interaction process mediated by graphene. Notably, we consider different electronic molecular orbitals, i.e. phthalocyanines with Cu and Mn metallic ions. The spectroscopic response suggests almost unaltered CuPc molecular states upon adsorption, and the rippled graphene carpet decouples completely the electronic interaction between the molecules and the Co layer, while a slight hybridization is present for MnPcs. MnPc molecules, trapped in the valleys of the moiré graphene superlattice, slightly intermix, through the orbitals protruding out of the molecular plane, with the underlying Co, while the organic ligands are almost unaltered. Graphene acts as an interlayer and mediates the interaction between metal phthalocyanines and the metallic substrate, preventing a strong chemical intermixing and enabling the assembly of almost unaltered molecules, preserving their electronic/magnetic state.
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Affiliation(s)
- Giulia Avvisati
- Sapienza University of Rome, Piazzale Aldo Moro, 5, I-00185 Rome, Italy
| | - Pierluigi Gargiani
- ALBA Synchrotron Light Source, Carrer de la Llum, 2-26, E-08290 Barcelona, Spain
| | | | - Francesco Presel
- Physics Department, University of Trieste, Via Valerio, 2, I-34127 Trieste, Italy
| | - Luca Bignardi
- Elettra Sincrotrone Trieste, S.S. 14, Km 163.5, I-34149 Basovizza, Trieste Italy
| | - Alessandro Baraldi
- Physics Department, University of Trieste, Via Valerio, 2, I-34127 Trieste, Italy
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Rosado Piquer L, Escoda-Torroella M, Ledezma Gairaud M, Carneros S, Daffé N, Studniarek M, Dreiser J, Wernsdorfer W, Sañudo EC. Hysteresis enhancement on a hybrid Dy(iii) single molecule magnet/iron oxide nanoparticle system. Inorg Chem Front 2019. [DOI: 10.1039/c8qi01346b] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
A novel hybrid NP-Dy12 system presents an enhancement of the magnetization hysteresis with respect to the isolated components while retaining the morphological characteristics of the parent NPs.
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Affiliation(s)
- Lidia Rosado Piquer
- Institut de Nanociència i Nanotecnologia-UB
- Barcelona
- Spain
- Secció de Química Inorgànica
- Departament de Química Inorgànica i Orgànica
| | - Mariona Escoda-Torroella
- Institut de Nanociència i Nanotecnologia-UB
- Barcelona
- Spain
- Secció de Química Inorgànica
- Departament de Química Inorgànica i Orgànica
| | - Marisol Ledezma Gairaud
- Escuela de Química
- Universidad de Costa Rica
- San José
- Costa Rica
- Centro de Electroquímica y Energía Química
| | - Saul Carneros
- Secció de Química Inorgànica
- Departament de Química Inorgànica i Orgànica
- Universitat de Barcelona
- Av. Diagonal 645
- Spain
| | - Niéli Daffé
- Swiss Light Source
- Paul Scherrer Institute
- Villigen PSI
- Switzerland
| | | | - Jan Dreiser
- Swiss Light Source
- Paul Scherrer Institute
- Villigen PSI
- Switzerland
| | | | - E. Carolina Sañudo
- Institut de Nanociència i Nanotecnologia-UB
- Barcelona
- Spain
- Secció de Química Inorgànica
- Departament de Química Inorgànica i Orgànica
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