1
|
Chen Q, Lodi A, Zhang H, Gee A, Wang HI, Kong F, Clarke M, Edmondson M, Hart J, O'Shea JN, Stawski W, Baugh J, Narita A, Saywell A, Bonn M, Müllen K, Bogani L, Anderson HL. Porphyrin-fused graphene nanoribbons. Nat Chem 2024; 16:1133-1140. [PMID: 38459234 PMCID: PMC11230900 DOI: 10.1038/s41557-024-01477-1] [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: 03/02/2023] [Accepted: 02/15/2024] [Indexed: 03/10/2024]
Abstract
Graphene nanoribbons (GNRs), nanometre-wide strips of graphene, are promising materials for fabricating electronic devices. Many GNRs have been reported, yet no scalable strategies are known for synthesizing GNRs with metal atoms and heteroaromatic units at precisely defined positions in the conjugated backbone, which would be valuable for tuning their optical, electronic and magnetic properties. Here we report the solution-phase synthesis of a porphyrin-fused graphene nanoribbon (PGNR). This PGNR has metalloporphyrins fused into a twisted fjord-edged GNR backbone; it consists of long chains (>100 nm), with a narrow optical bandgap (~1.0 eV) and high local charge mobility (>400 cm2 V-1 s-1 by terahertz spectroscopy). We use this PGNR to fabricate ambipolar field-effect transistors with appealing switching behaviour, and single-electron transistors displaying multiple Coulomb diamonds. These results open an avenue to π-extended nanostructures with engineerable electrical and magnetic properties by transposing the coordination chemistry of porphyrins into graphene nanoribbons.
Collapse
Affiliation(s)
- Qiang Chen
- Department of Chemistry, University of Oxford, Chemistry Research Laboratory, Oxford, UK.
- Max Planck Institute for Polymer Research, Mainz, Germany.
- Institute of Functional Nano & Soft Materials (FUNSOM), Soochow University, Suzhou, China.
| | | | - Heng Zhang
- Max Planck Institute for Polymer Research, Mainz, Germany
| | - Alex Gee
- Department of Materials, University of Oxford, Oxford, UK
| | - Hai I Wang
- Max Planck Institute for Polymer Research, Mainz, Germany
- Nanophotonics, Debye Institute for Nanomaterials Research, Utrecht University, Utrecht, the Netherlands
| | - Fanmiao Kong
- Department of Materials, University of Oxford, Oxford, UK
| | - Michael Clarke
- School of Physics & Astronomy, University of Nottingham, Nottingham, UK
| | - Matthew Edmondson
- School of Physics & Astronomy, University of Nottingham, Nottingham, UK
| | - Jack Hart
- School of Physics & Astronomy, University of Nottingham, Nottingham, UK
| | - James N O'Shea
- School of Physics & Astronomy, University of Nottingham, Nottingham, UK
| | - Wojciech Stawski
- Department of Chemistry, University of Oxford, Chemistry Research Laboratory, Oxford, UK
| | - Jonathan Baugh
- Institute for Quantum Computing, University of Waterloo, Waterloo, Ontario, Canada
| | | | - Alex Saywell
- School of Physics & Astronomy, University of Nottingham, Nottingham, UK
| | - Mischa Bonn
- Max Planck Institute for Polymer Research, Mainz, Germany
| | - Klaus Müllen
- Max Planck Institute for Polymer Research, Mainz, Germany
| | - Lapo Bogani
- Department of Materials, University of Oxford, Oxford, UK.
- Department of Chemistry & Physics, University of Florence, Sesto Fiorentino, Italy.
| | - Harry L Anderson
- Department of Chemistry, University of Oxford, Chemistry Research Laboratory, Oxford, UK.
| |
Collapse
|
2
|
Curti L, Prado Y, Michel A, Talbot D, Baptiste B, Otero E, Ohresser P, Journaux Y, Cartier-Dit-Moulin C, Dupuis V, Fleury B, Sainctavit P, Arrio MA, Fresnais J, Lisnard L. Room-temperature-persistent magnetic interaction between coordination complexes and nanoparticles in maghemite-based nanohybrids. NANOSCALE 2024; 16:10607-10617. [PMID: 38758111 DOI: 10.1039/d4nr01220h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2024]
Abstract
Maghemite nanoparticles functionalised with Co(II) coordination complexes at their surface show a significant increase of their magnetic anisotropy, leading to a doubling of the blocking temperature and a sixfold increase of the coercive field. Magnetometric studies suggest an enhancement that is not related to surface disordering, and point to a molecular effect involving magnetic exchange interactions mediated by the oxygen atoms at the interface as its source. Field- and temperature-dependent X-ray absorption spectroscopy (XAS) and X-ray magnetic circular dichroism (XMCD) studies show that the magnetic anisotropy enhancement is not limited to surface atoms and involves the core of the nanoparticle. These studies also point to a mechanism driven by anisotropic exchange and confirm the strength of the magnetic exchange interactions. The coupling between the complex and the nanoparticle persists at room temperature. Simulations based on the XMCD data give an effective exchange field value through the oxido coordination bridge between the Co(II) complex and the nanoparticle that is comparable to the exchange field between iron ions in bulk maghemite. Further evidence of the effectiveness of the oxido coordination bridge in mediating the magnetic interaction at the interface is given with the Ni(II) analog to the Co(II) surface-functionalised nanoparticles. A substrate-induced magnetic response is observed for the Ni(II) complexes, up to room temperature.
Collapse
Affiliation(s)
- Leonardo Curti
- Sorbonne Université, CNRS, Institut Parisien de Chimie Moléculaire, IPCM, F-75005, Paris, France.
| | - Yoann Prado
- Sorbonne Université, CNRS, Laboratoire de Physicochimie des Électrolytes et Nanosystèmes interfaciaux, PHENIX, F-75005, France.
| | - Aude Michel
- Sorbonne Université, CNRS, Laboratoire de Physicochimie des Électrolytes et Nanosystèmes interfaciaux, PHENIX, F-75005, France.
| | - Delphine Talbot
- Sorbonne Université, CNRS, Laboratoire de Physicochimie des Électrolytes et Nanosystèmes interfaciaux, PHENIX, F-75005, France.
| | - Benoît Baptiste
- CNRS, Sorbonne Université, IRD, MNHN, Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, IMPMC, F-75005, Paris, France.
| | - Edwige Otero
- Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin, BP 48, 91192 Gif-sur-Yvette, France
| | - Philippe Ohresser
- Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin, BP 48, 91192 Gif-sur-Yvette, France
| | - Yves Journaux
- Sorbonne Université, CNRS, Institut Parisien de Chimie Moléculaire, IPCM, F-75005, Paris, France.
| | | | - Vincent Dupuis
- Sorbonne Université, CNRS, Laboratoire de Physicochimie des Électrolytes et Nanosystèmes interfaciaux, PHENIX, F-75005, France.
| | - Benoit Fleury
- Sorbonne Université, CNRS, Institut Parisien de Chimie Moléculaire, IPCM, F-75005, Paris, France.
| | - Philippe Sainctavit
- CNRS, Sorbonne Université, IRD, MNHN, Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, IMPMC, F-75005, Paris, France.
- Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin, BP 48, 91192 Gif-sur-Yvette, France
| | - Marie-Anne Arrio
- CNRS, Sorbonne Université, IRD, MNHN, Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, IMPMC, F-75005, Paris, France.
| | - Jérôme Fresnais
- Sorbonne Université, CNRS, Laboratoire de Physicochimie des Électrolytes et Nanosystèmes interfaciaux, PHENIX, F-75005, France.
| | - Laurent Lisnard
- Sorbonne Université, CNRS, Institut Parisien de Chimie Moléculaire, IPCM, F-75005, Paris, France.
| |
Collapse
|
3
|
Tacconi L, Leiszner SS, Briganti M, Cucinotta G, Otero E, Mannini M, Perfetti M. Temperature Induced Reversible Switching of the Magnetic Anisotropy in a Neodymium Complex Adsorbed on Graphite. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2024:e2401627. [PMID: 38773906 DOI: 10.1002/smll.202401627] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2024] [Revised: 04/22/2024] [Indexed: 05/24/2024]
Abstract
Controlling the magnetic anisotropy of molecular layers assembled on a surface is one of the challenges that needs to be addressed to create the next-generation spintronic devices. Recently, metal complexes that show a reversible solid-state switch of their magnetic anisotropy in response to physical stimuli, such as temperature and magnetic field, have been discovered. The complex Nd(trensal) (H3trensal = 2,2',2''-tris(salicylideneimino)triethylamine) is predicted to exhibit such property. An ultra-thin film of Nd(trensal) is deposited on highly ordered pyrolytic graphite as a proof-of-concept system to show that this property can be retained at the nanoscale on a layered material. By combining single crystal magnetometric measurements and synchrotron X-ray-based absorption techniques, supported by multiplet ligand field simulations based on the trigonal crystal field surrounding the lanthanide centre, it is demonstrated that changing the temperature reverses the magnetic anisotropy of an ordered film of Nd(trensal), thus opening significant perspectives for the realization of a novel family of temperature-controlled molecular spintronic devices.
Collapse
Affiliation(s)
- Leonardo Tacconi
- Department of Chemistry "U. Schiff", Università degli Studi di Firenze & INSTM RU of Firenze, Via della Lastruccia 3-13, Sesto Fiorentino, 50019, Italy
| | - Sofie S Leiszner
- Department of Chemistry, Aarhus University, Langelandsgade 140, Aarhus C, 8000, Denmark
| | - Matteo Briganti
- Department of Chemistry "U. Schiff", Università degli Studi di Firenze & INSTM RU of Firenze, Via della Lastruccia 3-13, Sesto Fiorentino, 50019, Italy
| | - Giuseppe Cucinotta
- Department of Chemistry "U. Schiff", Università degli Studi di Firenze & INSTM RU of Firenze, Via della Lastruccia 3-13, Sesto Fiorentino, 50019, Italy
| | - Edwige Otero
- Synchrotron, SOLEIL, L'Orme des Merisiers, Saint-Aubin, 91190, France
| | - Matteo Mannini
- Department of Chemistry "U. Schiff", Università degli Studi di Firenze & INSTM RU of Firenze, Via della Lastruccia 3-13, Sesto Fiorentino, 50019, Italy
| | - Mauro Perfetti
- Department of Chemistry "U. Schiff", Università degli Studi di Firenze & INSTM RU of Firenze, Via della Lastruccia 3-13, Sesto Fiorentino, 50019, Italy
| |
Collapse
|
4
|
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.
Collapse
Affiliation(s)
| | - Md Ehesan Ali
- Institute of Nano Science and Technology, Mohali, Punjab 140306, India
| |
Collapse
|
5
|
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).
Collapse
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.
| |
Collapse
|
6
|
Tong L, Yu Z, Gao YJ, Li XC, Zheng JF, Shao Y, Wang YH, Zhou XS. Local cation-tuned reversible single-molecule switch in electric double layer. Nat Commun 2023; 14:3397. [PMID: 37296181 DOI: 10.1038/s41467-023-39206-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2022] [Accepted: 06/02/2023] [Indexed: 06/12/2023] Open
Abstract
The nature of molecule-electrode interface is critical for the integration of atomically precise molecules as functional components into circuits. Herein, we demonstrate that the electric field localized metal cations in outer Helmholtz plane can modulate interfacial Au-carboxyl contacts, realizing a reversible single-molecule switch. STM break junction and I-V measurements show the electrochemical gating of aliphatic and aromatic carboxylic acids have a conductance ON/OFF behavior in electrolyte solution containing metal cations (i.e., Na+, K+, Mg2+ and Ca2+), compared to almost no change in conductance without metal cations. In situ Raman spectra reveal strong molecular carboxyl-metal cation coordination at the negatively charged electrode surface, hindering the formation of molecular junctions for electron tunnelling. This work validates the critical role of localized cations in the electric double layer to regulate electron transport at the single-molecule level.
Collapse
Affiliation(s)
- Ling Tong
- Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, Institute of Physical Chemistry, Zhejiang Normal University, 321004, Jinhua, China
| | - Zhou Yu
- Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, Institute of Physical Chemistry, Zhejiang Normal University, 321004, Jinhua, China
| | - Yi-Jing Gao
- Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, Institute of Physical Chemistry, Zhejiang Normal University, 321004, Jinhua, China
- Zhejiang Engineering Laboratory for Green Syntheses and Applications of Fluorine-Containing Specialty Chemicals, Institute of Advanced Fluorine-Containing Materials, Zhejiang Normal University, 321004, Jinhua, China
| | - Xiao-Chong Li
- Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, Institute of Physical Chemistry, Zhejiang Normal University, 321004, Jinhua, China
| | - Ju-Fang Zheng
- Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, Institute of Physical Chemistry, Zhejiang Normal University, 321004, Jinhua, China
| | - Yong Shao
- Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, Institute of Physical Chemistry, Zhejiang Normal University, 321004, Jinhua, China
| | - Ya-Hao Wang
- Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, Institute of Physical Chemistry, Zhejiang Normal University, 321004, Jinhua, China.
| | - Xiao-Shun Zhou
- Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, Institute of Physical Chemistry, Zhejiang Normal University, 321004, Jinhua, China.
| |
Collapse
|
7
|
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.
Collapse
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
| |
Collapse
|
8
|
Kohn J, Bursch M, Hansen A, Grimme S. Computational study of ground-state properties of μ 2 -bridged group 14 porphyrinic sandwich complexes. J Comput Chem 2023; 44:229-239. [PMID: 35470911 DOI: 10.1002/jcc.26870] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Revised: 03/29/2022] [Accepted: 04/08/2022] [Indexed: 12/31/2022]
Abstract
The structural properties of μ2 -bridged porphyrinic double-decker complexes are investigated and the influence of various ligands, metals, substituents, and bridging atoms on the dominant structural motif is elucidated. A variety of quantum chemical methods including semiempirical (SQM) methods and density functional theory (DFT) is assessed for the calculation of ecliptic and staggered conformational energies. Local coupled cluster (DLPNO-CCSD(T1)) data are generated for reference. The r2 SCAN-3c composite scheme as well as the B2PLYP-D4/def2-QZVPP approach are identified as reliable methods. Energy decomposition analyses (EDA) and localized molecular orbital analyses (LMO) are used to investigate the bonding situation and the nature of the inter-ligand interaction energy underlining the crucial role of attractive London dispersion interactions. Targeted modification of the bridging atom, e.g., by replacing O2- by S2- is shown to drastically change the major structural features of the investigated complexes. Further, the influence of different substituents of varying size at the phthalocyanine ligand regarding the dominant conformation is described.
Collapse
Affiliation(s)
- Julia Kohn
- Mulliken Center for Theoretical Chemistry, University of Bonn, Bonn, Germany
| | - Markus Bursch
- Max-Planck-Institut für Kohlenforschung, Mülheim an der Ruhr, Germany
| | - Andreas Hansen
- Mulliken Center for Theoretical Chemistry, University of Bonn, Bonn, Germany
| | - Stefan Grimme
- Mulliken Center for Theoretical Chemistry, University of Bonn, Bonn, Germany
| |
Collapse
|
9
|
Moschkowitsch W, Samanta B, Zion N, Honig HC, Cullen DA, Caspary Toroker M, Elbaz L. NiFe-mixed metal porphyrin aerogels as oxygen evolution reaction catalysts in alkaline electrolysers. NANOSCALE 2022; 14:18033-18040. [PMID: 36445268 DOI: 10.1039/d2nr05675e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Aerogels are a very interesting group of materials owing to their unique physical and chemical properties. In the context of electrocatalysis, the focus has been on their physical properties, and they have been used primarily as catalyst supports so far. In this work, we synthesized porphyrin aerogels containing Ni and NiFe mixed metal materials and studied them as catalysts for the oxygen evolution reaction (OER). Different Ni : Fe ratios were synthesized and studied in electrochemical cells, and DFT calculations were conducted in order to gain insight into their behavior. The activity trends were dependent on the metal ratios and differ from known NiFeOOH materials due to the change in the oxidation states of the metals to higher numbers. Herein, we show that Ni and Fe have a synergistic effect on the OER, despite being structurally separated. They are connected electronically, though, through a large organic aromatic system that facilitates electron sharing between them. Among the mixed metal porphyrin aerogels, the best ratio was found to be Ni : Fe = 35 : 65, in contrast to oxide/oxyhydroxide materials in which a ratio of 80 : 20 was found to be ideal.
Collapse
Affiliation(s)
- Wenjamin Moschkowitsch
- Chemistry Department, Bar-Ilan University, Ramat-Gan 5290002, Israel
- Bar-Ilan Center for Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat-Gan 5290002, Israel.
| | - Bipasa Samanta
- Department of Materials Science and Engineering and The Nancy and Stephen Grand Technion Energy Program, Technion-Israel Institute of Technology, Haifa 3200003, Israel
| | - Noam Zion
- Chemistry Department, Bar-Ilan University, Ramat-Gan 5290002, Israel
- Bar-Ilan Center for Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat-Gan 5290002, Israel.
| | - Hilah C Honig
- Chemistry Department, Bar-Ilan University, Ramat-Gan 5290002, Israel
- Bar-Ilan Center for Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat-Gan 5290002, Israel.
| | - David A Cullen
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Maytal Caspary Toroker
- Bar-Ilan Center for Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat-Gan 5290002, Israel.
| | - Lior Elbaz
- Chemistry Department, Bar-Ilan University, Ramat-Gan 5290002, Israel
- Bar-Ilan Center for Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat-Gan 5290002, Israel.
| |
Collapse
|
10
|
Baranowski D, Cojocariu I, Sala A, Africh C, Comelli G, Schio L, Tormen M, Floreano L, Feyer V, Schneider CM. Conservation of Nickel Ion Single-Active Site Character in a Bottom-Up Constructed π-Conjugated Molecular Network. Angew Chem Int Ed Engl 2022; 61:e202210326. [PMID: 36070193 PMCID: PMC9827996 DOI: 10.1002/anie.202210326] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Indexed: 01/12/2023]
Abstract
On-surface chemistry holds the potential for ultimate miniaturization of functional devices. Porphyrins are promising building-blocks in exploring advanced nanoarchitecture concepts. More stable molecular materials of practical interest with improved charge transfer properties can be achieved by covalently interconnecting molecular units. On-surface synthesis allows to construct extended covalent nanostructures at interfaces not conventionally available. Here, we address the synthesis and properties of covalent molecular network composed of interconnected constituents derived from halogenated nickel tetraphenylporphyrin on Au(111). We report that the π-extended two-dimensional material exhibits dispersive electronic features. Concomitantly, the functional Ni cores retain the same single-active site character of their single-molecule counterparts. This opens new pathways when exploiting the high robustness of transition metal cores provided by bottom-up constructed covalent nanomeshes.
Collapse
Affiliation(s)
- Daniel Baranowski
- Peter Grünberg Institute (PGI-6)Jülich Research Center52428JülichGermany
| | - Iulia Cojocariu
- Peter Grünberg Institute (PGI-6)Jülich Research Center52428JülichGermany
| | | | | | - Giovanni Comelli
- TASC LaboratoryCNR-IOM34149TriesteItaly
- Department of PhysicsUniversity of Trieste34127TriesteItaly
| | | | | | | | - Vitaliy Feyer
- Peter Grünberg Institute (PGI-6)Jülich Research Center52428JülichGermany
- Faculty of Physics and Center for Nanointegration Duisburg-Essen (CENIDE)University of Duisburg-Essen47048DuisburgGermany
| | - Claus M. Schneider
- Peter Grünberg Institute (PGI-6)Jülich Research Center52428JülichGermany
- Faculty of Physics and Center for Nanointegration Duisburg-Essen (CENIDE)University of Duisburg-Essen47048DuisburgGermany
- Department of Physics and AstronomyUC DavisDavisCA 95616USA
| |
Collapse
|
11
|
Baranowski D, Cojocariu I, Sala A, Africh C, Comelli G, Schio L, Tormen M, Floreano L, Feyer V, Schneider CM. Conservation of Nickel Ion Single‐Active Site Character in a Bottom‐Up Constructed π‐Conjugated Molecular Network. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202210326] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Daniel Baranowski
- Forschungszentrum Jülich GmbH: Forschungszentrum Julich GmbH PGI-6 GERMANY
| | - Iulia Cojocariu
- Forschungszentrum Jülich GmbH: Forschungszentrum Julich GmbH PGI-6 GERMANY
| | | | | | - Giovanni Comelli
- University of Trieste: Universita degli Studi di Trieste Physics ITALY
| | | | | | | | - Vitaliy Feyer
- Forschungszentrum Julich GmbH Leo brand strasse GERMANY
| | - Claus M. Schneider
- Forschungszentrum Jülich: Forschungszentrum Julich GmbH PGI-6 Leo-Brandt-Straße 52425 Jülich GERMANY
| |
Collapse
|
12
|
Klyamer DD, Basova TV. EFFECT OF THE STRUCTURAL FEATURES OF METAL PHTHALOCYANINE FILMS ON THEIR ELECTROPHYSICAL PROPERTIES. J STRUCT CHEM+ 2022. [DOI: 10.1134/s0022476622070010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
|
13
|
Jo J, Calavalle F, Martín-García B, Tezze D, Casanova F, Chuvilin A, Hueso LE, Gobbi M. Exchange Bias in Molecule/Fe 3 GeTe 2 van der Waals Heterostructures via Spinterface Effects. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022; 34:e2200474. [PMID: 35334502 DOI: 10.1002/adma.202200474] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2022] [Revised: 03/06/2022] [Indexed: 06/14/2023]
Abstract
The exfoliation of layered magnetic materials generates atomically thin flakes characterized by an ultrahigh surface sensitivity, which makes their magnetic properties tunable via external stimuli, such as electrostatic gating and proximity effects. Another powerful approach to engineer magnetic materials is molecular functionalization, generating hybrid interfaces with tailored magnetic interactions, called spinterfaces. However, spinterface effects have not yet been explored on layered magnetic materials. Here, the emergence of spinterface effects is demonstrated at the interface between flakes of the prototypical layered magnetic metal Fe3 GeTe2 and thin films of Co-phthalocyanine. Magnetotransport measurements show that the molecular layer induces a magnetic exchange bias in Fe3 GeTe2 , indicating that the unpaired spins in Co-phthalocyanine develop antiferromagnetic ordering and pin the magnetization reversal of Fe3 GeTe2 via magnetic proximity. The effect is strongest for a Fe3 GeTe2 thickness of 20 nm, for which the exchange bias field reaches -840 Oe at 10 K and is measurable up to ≈110 K. This value compares very favorably with previous exchange bias fields reported for Fe3 GeTe2 in all-inorganic van der Waals heterostructures, demonstrating the potential of molecular functionalization to tailor the magnetism of van der Waals layered materials.
Collapse
Affiliation(s)
- Junhyeon Jo
- CIC nanoGUNE, Donostia-San Sebastian, Basque Country, 20018, Spain
| | | | | | - Daniel Tezze
- CIC nanoGUNE, Donostia-San Sebastian, Basque Country, 20018, Spain
| | - Fèlix Casanova
- CIC nanoGUNE, Donostia-San Sebastian, Basque Country, 20018, Spain
- IKERBASQUE, Basque Foundation for Science, Bilbao, Basque Country, 48013, Spain
| | - Andrey Chuvilin
- CIC nanoGUNE, Donostia-San Sebastian, Basque Country, 20018, Spain
- IKERBASQUE, Basque Foundation for Science, Bilbao, Basque Country, 48013, Spain
| | - Luis E Hueso
- CIC nanoGUNE, Donostia-San Sebastian, Basque Country, 20018, Spain
- IKERBASQUE, Basque Foundation for Science, Bilbao, Basque Country, 48013, Spain
| | - Marco Gobbi
- CIC nanoGUNE, Donostia-San Sebastian, Basque Country, 20018, Spain
- IKERBASQUE, Basque Foundation for Science, Bilbao, Basque Country, 48013, Spain
- Centro de Física de Materiales (CFM-MPC) Centro Mixto CSIC-UPV/EHU, San Sebastián/Donostia, 20018, Spain
| |
Collapse
|
14
|
Johnson KN, Chilukurib B, Fisherb ZE, Hippsa KW, Mazura U. Role of the Supporting Surface in the Thermodynamics and Cooperativity of Axial Ligand Binding to Metalloporphyrins at Interfaces. CURR ORG CHEM 2022. [DOI: 10.2174/1385272826666220209122508] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Abstract:
: Metalloporphyrins have been shown to bind axial ligands in a variety of environments including the vacuum/solid and solution/solid interfaces. Understanding the dynamics of such interactions is a desideratum for the design and implementation of next generation molecular devices which draw inspiration from biological systems to accomplish diverse tasks such as molecular sensing, electron transport, and catalysis to name a few. In this article, we review the current literature of axial ligand coordination to surface-supported porphyrin receptors. We will focus on the coordination process as monitored by scanning tunneling microscopy (STM) that can yield qualitative and quantitative information on the dynamics and binding affinity at the single molecule level. In particular, we will address the role of the substrate and intermolecular interactions in influencing cooperative effects (positive or negative) in the binding affinity of adjacent molecules based on experimental evidence and theoretical calculations.
Collapse
Affiliation(s)
- Kristen N. Johnson
- Department of Chemistry and Material Science and Engineering Program, Washington State University, Pullman, 99164-4630, WA, USA
| | - Bhaskar Chilukurib
- Department of Chemistry, Illinois State University, Normal, IL, 61790-4160, USA
| | - Zachary E. Fisherb
- Department of Chemistry, Illinois State University, Normal, IL, 61790-4160, USA
| | - K. W. Hippsa
- Department of Chemistry and Material Science and Engineering Program, Washington State University, Pullman, 99164-4630, WA, USA
| | - Ursula Mazura
- Department of Chemistry and Material Science and Engineering Program, Washington State University, Pullman, 99164-4630, WA, USA
| |
Collapse
|
15
|
The Magnetic Behaviour of CoTPP Supported on Coinage Metal Surfaces in the Presence of Small Molecules: A Molecular Cluster Study of the Surface trans-Effect. NANOMATERIALS 2022; 12:nano12020218. [PMID: 35055236 PMCID: PMC8778902 DOI: 10.3390/nano12020218] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Revised: 01/06/2022] [Accepted: 01/08/2022] [Indexed: 01/25/2023]
Abstract
Density functional theory, combined with the molecular cluster model, has been used to investigate the surface trans-effect induced by the coordination of small molecules L (L = CO, NH3, NO, NO2 and O2) on the cobalt electronic structure of cobalt tetraphenylporphyrinato (CoTPP) surface-supported on coinage metal surfaces (Cu, Ag, and Au). Regardless of whether L has a closed- or an open-shell electronic structure, its coordination to Co takes out the direct interaction between Co and the substrate eventually present. The CO and NH3 bonding to CoTPP does not influence the Co local electronic structure, while the NO (NO2 and O2) coordination induces a Co reduction (oxidation), generating a 3d8 CoI (3d6 CoIII) magnetically silent closed-shell species. Theoretical outcomes herein reported demonstrate that simple and computationally inexpensive models can be used not only to rationalize but also to predict the effects of the Co–L bonding on the magnetic behaviour of CoTPP chemisorbed on coinage metals. The same model may be straightforwardly extended to other transition metals or coordinated molecules.
Collapse
|
16
|
Sturmeit HM, Cojocariu I, Windischbacher A, Puschnig P, Piamonteze C, Jugovac M, Sala A, Africh C, Comelli G, Cossaro A, Verdini A, Floreano L, Stredansky M, Vesselli E, Hohner C, Kettner M, Libuda J, Schneider CM, Zamborlini G, Cinchetti M, Feyer V. Room-Temperature On-Spin-Switching and Tuning in a Porphyrin-Based Multifunctional Interface. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2021; 17:e2104779. [PMID: 34643036 DOI: 10.1002/smll.202104779] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Indexed: 06/13/2023]
Abstract
Molecular interfaces formed between metals and molecular compounds offer a great potential as building blocks for future opto-electronics and spintronics devices. Here, a combined theoretical and experimental spectro-microscopy approach is used to show that the charge transfer occurring at the interface between nickel tetraphenyl porphyrins and copper changes both spin and oxidation states of the Ni ion from [Ni(II), S = 0] to [Ni(I), S = 1/2]. The chemically active Ni(I), even in a buried multilayer system, can be functionalized with nitrogen dioxide, allowing a selective tuning of the electronic properties of the Ni center that is switched to a [Ni(II), S = 1] state. While Ni acts as a reversible spin switch, it is found that the electronic structure of the macrocycle backbone, where the frontier orbitals are mainly localized, remains unaffected. These findings pave the way for using the present porphyrin-based system as a platform for the realization of multifunctional devices where the magnetism and the optical/transport properties can be controlled simultaneously by independent stimuli.
Collapse
Affiliation(s)
| | - Iulia Cojocariu
- Peter Grünberg Institute (PGI-6), Jülich Research Centre, 52425, Jülich, Germany
| | - Andreas Windischbacher
- Institute of Physics, University of Graz, Karl-Franzens-Universität Graz, Graz, 8010, Austria
| | - Peter Puschnig
- Institute of Physics, University of Graz, Karl-Franzens-Universität Graz, Graz, 8010, Austria
| | - Cinthia Piamonteze
- Swiss Light Source, Paul Scherrer Institute, Villigen, CH-5232, Switzerland
| | - Matteo Jugovac
- Peter Grünberg Institute (PGI-6), Jülich Research Centre, 52425, Jülich, Germany
| | - Alessandro Sala
- CNR-IOM, TASC Laboratory, Trieste, 34149, Italy
- Department of Physics, University of Trieste, Trieste, 34127, Italy
| | | | - Giovanni Comelli
- CNR-IOM, TASC Laboratory, Trieste, 34149, Italy
- Department of Physics, University of Trieste, Trieste, 34127, Italy
| | - Albano Cossaro
- CNR-IOM, TASC Laboratory, Trieste, 34149, Italy
- Department of Chemical and Pharmaceutical Sciences, University of Trieste, Trieste, 34127, Italy
| | | | | | - Matus Stredansky
- CNR-IOM, TASC Laboratory, Trieste, 34149, Italy
- Department of Physics, University of Trieste, Trieste, 34127, Italy
| | - Erik Vesselli
- CNR-IOM, TASC Laboratory, Trieste, 34149, Italy
- Department of Physics, University of Trieste, Trieste, 34127, Italy
| | - Chantal Hohner
- Interface Research and Catalysis, Erlangen Center for Interface Research and Catalysis, Friedrich-Alexander University Erlangen-Nuremberg, 91058, Erlangen, Germany
| | - Miroslav Kettner
- Interface Research and Catalysis, Erlangen Center for Interface Research and Catalysis, Friedrich-Alexander University Erlangen-Nuremberg, 91058, Erlangen, Germany
| | - Jörg Libuda
- Interface Research and Catalysis, Erlangen Center for Interface Research and Catalysis, Friedrich-Alexander University Erlangen-Nuremberg, 91058, Erlangen, Germany
| | - Claus Michael Schneider
- Peter Grünberg Institute (PGI-6), Jülich Research Centre, 52425, Jülich, Germany
- Faculty of Physics and Center for Nanointegration Duisburg-Essen (CENIDE), University of Duisburg-Essen, 47048, Duisburg, Germany
| | | | - Mirko Cinchetti
- TU Dortmund University, Experimental Physics VI, 44227, Dortmund, Germany
| | - Vitaliy Feyer
- Peter Grünberg Institute (PGI-6), Jülich Research Centre, 52425, Jülich, Germany
- Faculty of Physics and Center for Nanointegration Duisburg-Essen (CENIDE), University of Duisburg-Essen, 47048, Duisburg, Germany
| |
Collapse
|
17
|
Zhao Y, Gobbi M, Hueso LE, Samorì P. Molecular Approach to Engineer Two-Dimensional Devices for CMOS and beyond-CMOS Applications. Chem Rev 2021; 122:50-131. [PMID: 34816723 DOI: 10.1021/acs.chemrev.1c00497] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Two-dimensional materials (2DMs) have attracted tremendous research interest over the last two decades. Their unique optical, electronic, thermal, and mechanical properties make 2DMs key building blocks for the fabrication of novel complementary metal-oxide-semiconductor (CMOS) and beyond-CMOS devices. Major advances in device functionality and performance have been made by the covalent or noncovalent functionalization of 2DMs with molecules: while the molecular coating of metal electrodes and dielectrics allows for more efficient charge injection and transport through the 2DMs, the combination of dynamic molecular systems, capable to respond to external stimuli, with 2DMs makes it possible to generate hybrid systems possessing new properties by realizing stimuli-responsive functional devices and thereby enabling functional diversification in More-than-Moore technologies. In this review, we first introduce emerging 2DMs, various classes of (macro)molecules, and molecular switches and discuss their relevant properties. We then turn to 2DM/molecule hybrid systems and the various physical and chemical strategies used to synthesize them. Next, we discuss the use of molecules and assemblies thereof to boost the performance of 2D transistors for CMOS applications and to impart diverse functionalities in beyond-CMOS devices. Finally, we present the challenges, opportunities, and long-term perspectives in this technologically promising field.
Collapse
Affiliation(s)
- Yuda Zhao
- University of Strasbourg, CNRS, ISIS UMR 7006, 8 allée Gaspard Monge, F-67000 Strasbourg, France.,School of Micro-Nano Electronics, ZJU-Hangzhou Global Scientific and Technological Innovation Centre, Zhejiang University, 38 Zheda Road, 310027 Hangzhou, People's Republic of China
| | - Marco Gobbi
- Centro de Fisica de Materiales (CSIC-UPV/EHU), Paseo Manuel de Lardizabal 5, E-20018 Donostia-San Sebastián, Spain.,CIC nanoGUNE, E-20018 Donostia-San Sebastian, Basque Country, Spain.,IKERBASQUE, Basque Foundation for Science, 48009 Bilbao, Spain
| | - Luis E Hueso
- CIC nanoGUNE, E-20018 Donostia-San Sebastian, Basque Country, Spain.,IKERBASQUE, Basque Foundation for Science, 48009 Bilbao, Spain
| | - Paolo Samorì
- University of Strasbourg, CNRS, ISIS UMR 7006, 8 allée Gaspard Monge, F-67000 Strasbourg, France
| |
Collapse
|
18
|
Wang A, Peng J, Ren N, Ding L, Yu X, Wang Z, Zhao M. Spin-Gapless States in Two-Dimensional Molecular Ferromagnet Fe 2(TCNQ) 2. J Phys Chem Lett 2021; 12:7921-7927. [PMID: 34384211 DOI: 10.1021/acs.jpclett.1c01869] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Two-dimensional van der Waals magnetic atomic crystals have provided unprecedented access to magnetic ground states due to a quantum confinement effect. Here, using first-principles calculations, we demonstrate a spin-gapless molecular ferromagnet, namely, Fe2(TCNQ)2, with superior mechanical stability and a remarkable linear Dirac cone, which can be exfoliated from its already-synthesized van der Waals crystal. Especially, Young's modulus has values of 175.28 GPa·nm along the x- and y-directions with a Poisson's ratio of 0.29, while the Curie temperature within the Ising model is considerably higher than room temperature. Furthermore, spin-orbit coupling can open a band gap at the Dirac point, leading to topologically nontrivial electronic states characterized by an integer value of the Chern number and the edge states of its nanoribbon. Our results offer versatile platforms for achieving plastic spin filtering or a quantum anomalous Hall effect with promising applications in spintronics devices.
Collapse
Affiliation(s)
- Aizhu Wang
- Institute for Advanced Interdisciplinary Research, University of Jinan, Jinan, Shandong 250022, China
| | - Jingyang Peng
- School of Science, Royal Melbourne Institute of Technology University, Melbourne, Victoria 3001, Australia
| | - Na Ren
- Institute for Advanced Interdisciplinary Research, University of Jinan, Jinan, Shandong 250022, China
| | - Longhua Ding
- Institute for Advanced Interdisciplinary Research, University of Jinan, Jinan, Shandong 250022, China
| | - Xin Yu
- Institute for Advanced Interdisciplinary Research, University of Jinan, Jinan, Shandong 250022, China
| | - Zhenhai Wang
- College of Telecommunications & Information Engineering, Nanjing University of Posts and Telecommunications, Nanjing, Jiangsu 210003, China
| | - Mingwen Zhao
- School of Physics and State Key Laboratory of Crystal Materials, Shandong University, Jinan, Shandong 250100, China
| |
Collapse
|
19
|
First-principles study of hybrid nanostructures formed by deposited phthalocyanine/porphyrin metal complexes on phosphorene. J Mol Liq 2021. [DOI: 10.1016/j.molliq.2021.115948] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
|
20
|
Liu Y, Bian Y, Zhang Y, Hang C, Zhang X, Lou S, Jin Q. Fluorescence of CoTPP Mediated by the Plasmon-Exciton Coupling Effect in the Tunneling Junction. J Phys Chem Lett 2021; 12:5349-5356. [PMID: 34076440 DOI: 10.1021/acs.jpclett.1c01123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
CoTPP, as a common hypsoporphyrin, is usually not a luminescent molecule because of the open-shell Co ion. In this paper, well-defined multilayer CoTPP molecules self-assembled on Au(111) surface are characterized layer by layer with scanning tunneling microscope (STM) induced luminescence. By using the highly localized STM tunneling current, we not only investigate the influence of bias polarity on the amplitude of distinct plasmonic emission resulted from the interaction between the metal substrate and the metal ions but also first obtain the light emission from the hypsoporphyrins in the tunneling junction. The density-matrix method and the combined approach of classical electrodynamics and first-principles calculation are used to explain the mechanism of the light emission. These findings may expand the underlying physics of plasmon-exciton coupling in STM nanocavity and reveal a new possible path to overcome the fluorescent potential of hypsoporphyrins by the intense localized electric fields.
Collapse
Affiliation(s)
- Yiting Liu
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062, P. R. China
| | - Yajie Bian
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062, P. R. China
| | - Yuyi Zhang
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062, P. R. China
| | - Chao Hang
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062, P. R. China
| | - Xiaolei Zhang
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062, P. R. China
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, Shanxi 030006, P. R. China
| | - Shitao Lou
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062, P. R. China
| | - Qingyuan Jin
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062, P. R. China
- Department of Optical Science and Engineering, Fudan University, Shanghai 200433, China
| |
Collapse
|
21
|
Montero AM, Guimarães FSM, Lounis S. Multiple magnetic states of CoPc molecule on a two-dimensional layer of NbSe 2. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 33:205802. [PMID: 33704093 DOI: 10.1088/1361-648x/abed64] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Accepted: 03/10/2021] [Indexed: 06/12/2023]
Abstract
Molecular spintronics hinges on the detailed understanding of electronic and magnetic properties of molecules interfaced with various materials. Here we demonstrate withab initiosimulations that the prototypical Co-phthalocyanine (CoPc) molecule can surprisingly develop multi-spin states once deposited on the two-dimensional 2H-NbSe2layer. Conventional calculations based on density functional theory (DFT) show the existence of low, regular and high spin states, which reduce to regular and high spins states once correlations are incorporated with a DFT +Uapproach. Depending onU, the ground state is either the low spin or high spin state with energy differences affected by the molecular orientation on top of the substrate. Our results are compared to recent scanning probe measurements and motivate further theoretical and experimental studies on the unveiled rich multi-magnetic behavior of CoPc molecule.
Collapse
Affiliation(s)
- Ana M Montero
- Peter Grünberg Institut and Institute for Advanced Simulation, Forschungszetrum Jülich and JARA, 52425 Jülich, Germany
| | - Filipe S M Guimarães
- Jülich Supercomputing Centre, Forschungszentrum Jülich and JARA, 52425 Jülich, Germany
| | - Samir Lounis
- Peter Grünberg Institut and Institute for Advanced Simulation, Forschungszetrum Jülich and JARA, 52425 Jülich, Germany
- Faculty of Physics, University of Duisburg-Essen and CENIDE, 47053 Duisburg, Germany
| |
Collapse
|
22
|
Castelli M, Hellerstedt J, Krull C, Gicev S, Hollenberg LCL, Usman M, Schiffrin A. Long-Range Surface-Assisted Molecule-Molecule Hybridization. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2021; 17:e2005974. [PMID: 33576182 DOI: 10.1002/smll.202005974] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Revised: 12/15/2020] [Indexed: 06/12/2023]
Abstract
Metalated phthalocyanines (Pc's) are robust and versatile molecular complexes, whose properties can be tuned by changing their functional groups and central metal atom. The electronic structure of magnesium Pc (MgPc)-structurally and electronically similar to chlorophyll-adsorbed on the Ag(100) surface is investigated by low-temperature scanning tunneling microscopy and spectroscopy, non-contact atomic force microscopy, and density functional theory. Single, isolated MgPc's exhibit a flat, fourfold rotationally symmetric morphology, with doubly degenerate, partially populated (due to surface-to-molecule electron transfer) lowest unoccupied molecular orbitals (LUMOs). In contrast, MgPc's with neighbouring molecules in proximity undergo a lift of LUMOs degeneracy, with a near-Fermi local density of states with reduced twofold rotational symmetry, indicative of a long-range attractive intermolecular interaction. The latter is assigned to a surface-mediated two-step electronic hybridization process. First, LUMOs interact with Ag(100) conduction electrons, forming hybrid molecule-surface orbitals with enhanced spatial extension. Then, these delocalized molecule-surface states further hybridize with those of neighbouring molecules. This work highlights how the electronic structure of molecular adsorbates-including orbital degeneracies and symmetries-can be significantly altered via surface-mediated intermolecular hybridization, over extended distances (beyond 3 nm), having important implications for prospects of molecule-based solid-state technologies.
Collapse
Affiliation(s)
- Marina Castelli
- School of Physics and Astronomy, Monash University, Clayton, Victoria, 3800, Australia
- ARC Centre of Excellence in Future Low-Energy Electronics Technologies, Monash University, Clayton, Victoria, 3800, Australia
| | - Jack Hellerstedt
- School of Physics and Astronomy, Monash University, Clayton, Victoria, 3800, Australia
| | - Cornelius Krull
- School of Physics and Astronomy, Monash University, Clayton, Victoria, 3800, Australia
- ARC Centre of Excellence in Future Low-Energy Electronics Technologies, Monash University, Clayton, Victoria, 3800, Australia
| | - Spiro Gicev
- Centre for Quantum Computation and Communication Technology, School of Physics, The University of Melbourne, Parkville, Victoria, 3010, Australia
| | - Lloyd C L Hollenberg
- Centre for Quantum Computation and Communication Technology, School of Physics, The University of Melbourne, Parkville, Victoria, 3010, Australia
| | - Muhammad Usman
- Centre for Quantum Computation and Communication Technology, School of Physics, The University of Melbourne, Parkville, Victoria, 3010, Australia
- School of Computing and Information Systems, Melbourne School of Engineering, The University of Melbourne, Parkville, Victoria, 3010, Australia
| | - Agustin Schiffrin
- School of Physics and Astronomy, Monash University, Clayton, Victoria, 3800, Australia
- ARC Centre of Excellence in Future Low-Energy Electronics Technologies, Monash University, Clayton, Victoria, 3800, Australia
| |
Collapse
|
23
|
Brozyniak A, Mendirek G, Hohage M, Navarro-Quezada A, Zeppenfeld P. In situ electromagnet with active cooling for real-time magneto-optic Kerr effect spectroscopy. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2021; 92:025105. [PMID: 33648095 DOI: 10.1063/5.0039608] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Accepted: 01/21/2021] [Indexed: 06/12/2023]
Abstract
We present a compact in situ electromagnet with an active cooling system for use in ultrahigh vacuum environments. The active cooling enhances the thermal stability and increases the electric current that can be applied through the coil, promoting the generation of homogeneous magnetic fields, required for applications in real-time deposition experiments. The electromagnet has been integrated into a reflectance difference magneto-optic Kerr effect (RD-MOKE) spectroscopy system that allows the synchronous measurement of the optical anisotropy and the magneto-optic response in polar MOKE geometry. Proof of principle studies have been performed in real time during the deposition of ultra-thin Ni films on Cu(110)-(2 × 1)O surfaces, corroborating the extremely sharp spin reorientation transition above a critical coverage of 9 monolayers and demonstrating the potential of the applied setup for real-time and in situ investigations of magnetic thin films and interfaces.
Collapse
Affiliation(s)
- A Brozyniak
- Institute of Experimental Physics, Johannes Kepler University, Altenberger Str. 69, 4040 Linz, Austria
| | - G Mendirek
- Institute of Experimental Physics, Johannes Kepler University, Altenberger Str. 69, 4040 Linz, Austria
| | - M Hohage
- Institute of Experimental Physics, Johannes Kepler University, Altenberger Str. 69, 4040 Linz, Austria
| | - A Navarro-Quezada
- Institute of Semiconductor and Solid State Physics, Johannes Kepler University, Altenberger Str. 69, 4040 Linz, Austria
| | - P Zeppenfeld
- Institute of Experimental Physics, Johannes Kepler University, Altenberger Str. 69, 4040 Linz, Austria
| |
Collapse
|
24
|
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.
Collapse
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
| |
Collapse
|
25
|
De Luca O, Caruso T, Grimaldi I, Policicchio A, Formoso V, Fujii J, Vobornik I, Pacilé D, Papagno M, Agostino RG. Zinc(II) tetraphenylporphyrin on Au(111) investigated by scanning tunnelling microscopy and photoemission spectroscopy measurements. NANOTECHNOLOGY 2020; 31:365603. [PMID: 32442980 DOI: 10.1088/1361-6528/ab95ba] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Porphyrins are a versatile class of molecules, which have attracted attention over the years due to their electronic, optical and biological properties. Self-assembled monolayers of porphyrins were widely studied on metal surfaces in order to understand the supramolecular organization of these molecules, which is a crucial step towards the development of devices starting from the bottom-up approach. This perspective could lead to tailor the interfacial properties of the surface, depending on the specific interaction between the molecular assembly and the metal surface. In this study, we revisit the investigation of the assembly of zinc-tetraphenylporphyrins on Au(111) in order to explore the adsorption of the molecular network on the noble metal substrate. The combined analysis of scanning tunneling microscopy (STM) imaging and core levels photoemission spectroscopy measurements support a peculiar arrangement of the ZnTPP molecular network, with Zn atoms occupying the bridge sites of the Au surface atoms. Furthermore, we prove that, at few-layers coverage, the interaction between the deposited layers allows a relevant molecular mobility of the adlayer, as observed by STM and supported by core levels photoemission analysis.
Collapse
Affiliation(s)
- Oreste De Luca
- Dipartimento di Fisica, Università della Calabria, 87036, Arcavacata di Rende(CS), Italy. CNR-Nanotec, UoS di Cosenza, Dipartimento di Fisica, Università della Calabria, 87036, Arcavacata di Rende (CS), Italy
| | | | | | | | | | | | | | | | | | | |
Collapse
|
26
|
Abstract
We introduce a computational approach to study porphyrin-like transition metal complexes, bridging density functional theory and exact many-body techniques, such as the density matrix renormalization group (DMRG). We first derive a multi-orbital Anderson impurity Hamiltonian starting from first principles considerations that qualitatively reproduce generalized gradient approximation (GGA)+U results when ignoring inter-orbital Coulomb repulsion U ′ and Hund exchange J. An exact canonical transformation is used to reduce the dimensionality of the problem and make it amenable to DMRG calculations, including all many-body terms (both intra- and inter-orbital), which are treated in a numerically exact way. We apply this technique to FeN 4 centers in graphene and show that the inclusion of these terms has dramatic effects: as the iron orbitals become single occupied due to the Coulomb repulsion, the inter-orbital interaction further reduces the occupation, yielding a non-monotonic behavior of the magnetic moment as a function of the interactions, with maximum polarization only in a small window at intermediate values of the parameters. Furthermore, U ′ changes the relative position of the peaks in the density of states, particularly on the iron d z 2 orbital, which is expected to affect the binding of ligands greatly.
Collapse
|
27
|
Azuri I, Ali ME, Tarafder K, Oppeneer PM, Kronik L. Fe‐porphyrin on Co(001) and Cu(001): A Comparative Dispersion‐augmented Density Functional Theory Study. Isr J Chem 2020. [DOI: 10.1002/ijch.201900123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Ido Azuri
- Department of Materials and Interfaces Weizmann Institute of Science Rehovoth 76100 Israel
| | - Md. Ehesan Ali
- Institute of Nano Science and Technology, Phase-10, Sector-64 Mohali 160062, Punjab India
| | - Kartick Tarafder
- Department of Physics National Institute of Technology Karnataka, Srinivasnagar, Surathkal Mangalore 575025 India
| | - Peter M. Oppeneer
- Department of Physics and Astronomy Uppsala University Box 516 S-75120 Uppsala Sweden
| | - Leeor Kronik
- Department of Materials and Interfaces Weizmann Institute of Science Rehovoth 76100 Israel
| |
Collapse
|
28
|
Castriciano MA, Trapani M, Romeo A, Depalo N, Rizzi F, Fanizza E, Patanè S, Monsù Scolaro L. Influence of Magnetic Micelles on Assembly and Deposition of Porphyrin J-Aggregates. NANOMATERIALS (BASEL, SWITZERLAND) 2020; 10:E187. [PMID: 31973230 PMCID: PMC7074871 DOI: 10.3390/nano10020187] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Revised: 01/14/2020] [Accepted: 01/16/2020] [Indexed: 12/13/2022]
Abstract
Clusters of superparamagnetic iron oxide nanoparticles (SPIONs) have been incorporated into the hydrophobic core of polyethylene glycol (PEG)-modified phospholipid micelles. Two different PEG-phospholipids have been selected to guarantee water solubility and provide an external corona, bearing neutral (SPIONs@PEG-micelles) or positively charged amino groups (SPIONs@NH2-PEG-micelles). Under acidic conditions and with specific mixing protocols (porphyrin first, PF, or porphyrin last, PL), the water-soluble 5,10,15,20-tetrakis-(4-sulfonatophenyl)-porphyrin (TPPS) forms chiral J-aggregates, and in the presence of the two different types of magnetic micelles, an increase of the aggregation rates has been generally observed. In the case of the neutral SPIONs@PEG-micelles, PL protocol affords a stable nanosystem, whereas PF protocol is effective with the charged SPIONs@NH2-PEG-micelles. In both cases, chiral J-aggregates embedded into the magnetic micelles (TPPS@SPIONs@micelles) have been characterized in solution through UV/vis absorption and circular/linear dichroism. An external magnetic field allows depositing films of the TPPS@SPIONs@micelles that retain their chiroptical properties and exhibit a high degree of alignment, which is also confirmed by atomic force microscopy.
Collapse
Affiliation(s)
- Maria Angela Castriciano
- CNR-ISMN, Istituto per lo Studio dei Materiali Nanostrutturati c/o Dipartimento di Scienze Chimiche, Biologiche, Farmaceutiche ed Ambientali, University of Messina V.le F. Stagno D’Alcontres, 31 98166 Messina, Italy; (M.T.); (A.R.)
| | - Mariachiara Trapani
- CNR-ISMN, Istituto per lo Studio dei Materiali Nanostrutturati c/o Dipartimento di Scienze Chimiche, Biologiche, Farmaceutiche ed Ambientali, University of Messina V.le F. Stagno D’Alcontres, 31 98166 Messina, Italy; (M.T.); (A.R.)
| | - Andrea Romeo
- CNR-ISMN, Istituto per lo Studio dei Materiali Nanostrutturati c/o Dipartimento di Scienze Chimiche, Biologiche, Farmaceutiche ed Ambientali, University of Messina V.le F. Stagno D’Alcontres, 31 98166 Messina, Italy; (M.T.); (A.R.)
- Dipartimento di Scienze Chimiche, Biologiche, Farmaceutiche ed Ambientali and C.I.R.C.M.S.B., University of Messina V.le F. Stagno D’Alcontres, 31 98166 Messina, Italy
| | - Nicoletta Depalo
- CNR-IPCF, Istituto Per i Processi Chimico-Fisici, 70124 Bari, Italy; (N.D.); (F.R.); (E.F.)
| | - Federica Rizzi
- CNR-IPCF, Istituto Per i Processi Chimico-Fisici, 70124 Bari, Italy; (N.D.); (F.R.); (E.F.)
- Dipartimento di Chimica, Università degli Studi di Bari Aldo Moro, Via Orabona 4, 70125 Bari, Italy
| | - Elisabetta Fanizza
- CNR-IPCF, Istituto Per i Processi Chimico-Fisici, 70124 Bari, Italy; (N.D.); (F.R.); (E.F.)
- Dipartimento di Chimica, Università degli Studi di Bari Aldo Moro, Via Orabona 4, 70125 Bari, Italy
| | - Salvatore Patanè
- Dipartimento di Scienze Matematiche e Informatiche, Scienze Fisiche e Scienze della Terra, University of Messina V.le F. Stagno D’Alcontres, 31 98166 Messina, Italy;
| | - Luigi Monsù Scolaro
- CNR-ISMN, Istituto per lo Studio dei Materiali Nanostrutturati c/o Dipartimento di Scienze Chimiche, Biologiche, Farmaceutiche ed Ambientali, University of Messina V.le F. Stagno D’Alcontres, 31 98166 Messina, Italy; (M.T.); (A.R.)
- Dipartimento di Scienze Chimiche, Biologiche, Farmaceutiche ed Ambientali and C.I.R.C.M.S.B., University of Messina V.le F. Stagno D’Alcontres, 31 98166 Messina, Italy
| |
Collapse
|
29
|
Structure, Properties, and Reactivity of Porphyrins on Surfaces and Nanostructures with Periodic DFT Calculations. APPLIED SCIENCES-BASEL 2020. [DOI: 10.3390/app10030740] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Porphyrins are fascinating molecules with applications spanning various scientific fields. In this review we present the use of periodic density functional theory (PDFT) calculations to study the structure, electronic properties, and reactivity of porphyrins on ordered two dimensional surfaces and in the formation of nanostructures. The focus of the review is to describe the application of PDFT calculations for bridging the gaps in experimental studies on porphyrin nanostructures and self-assembly on 2D surfaces. A survey of different DFT functionals used to study the porphyrin-based system as well as their advantages and disadvantages in studying these systems is presented.
Collapse
|
30
|
Tseng HH, Serri M, Harrison N, Heutz S. Properties and degradation of manganese(III) porphyrin thin films formed by high vacuum sublimation. J PORPHYR PHTHALOCYA 2020. [DOI: 10.1142/s1088424619501700] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Manganese porphyrins are of interest due to the optical, electronic and magnetic properties of the central metal ion, coupled to the low bandgap of the polyaromatic ring. These attractive characteristics are harnessed in solutions or in ultra-thin films, such as, for example, self-assembled monolayers. However, for devices, thicker films deposited using a controlled and reproducible method are required. Here we present the morphological, structural, chemical and optical properties of manganese(III) tetraphenylporphyrin chloride (MnTPPCl) thin films deposited using organic molecular beam deposition, typically employed to process analogue molecules for applications such as organic photovoltaics. We find, using a combination of UV-vis and X-ray photoelectron spectroscopies, that the sublimation process leads to the scission of the Mn–Cl bond. The resultant film is a Mn(II)TPP:Mn(III)TPPCl blend where approximately half the molecules have been reduced. Following growth, exposure to air oxidizes the Mn(II)TPP molecule. Through quantitative analysis of the time-dependent optical properties, the oxygen diffusion coefficient (D) [Formula: see text] is obtained, corresponding to a slow bulk oxidation following fast oxidation of a 8-nm-thick surface layer. The bulk diffusion D is lower than for analogous polycrystalline films, suggestion that grain boundaries, rather than molecular packing, are the rate-limiting steps in oxidation of molecular films. Our results highlight that the stability of the axial ligands should be considered when depositing metal porphyrins from the vapor phase, and offer a solvent-free route to obtain reproducible and smooth thin films of complex materials for engineering film functionalities.
Collapse
Affiliation(s)
- Hsiang-Han Tseng
- Department of Materials and London Centre for Nanotechnology, Imperial College London, London SW7 2AZ, UK
| | - Michele Serri
- Department of Materials and London Centre for Nanotechnology, Imperial College London, London SW7 2AZ, UK
| | - Nicholas Harrison
- Department of Chemistry and Institute for Molecular Science and Engineering, Imperial College London, White City Campus, 80 Wood Lane, Imperial College London, London W12 0BZ, UK
| | - Sandrine Heutz
- Department of Materials and London Centre for Nanotechnology, Imperial College London, London SW7 2AZ, UK
- Centre for Plastic Electronics, Imperial College London, London SW7 2AZ, UK
| |
Collapse
|
31
|
Gamou H, Shimose K, Enoki R, Minamitani E, Shiotari A, Kotani Y, Toyoki K, Nakamura T, Sugimoto Y, Kohda M, Nitta J, Miwa S. Detection of Spin Transfer from Metal to Molecule by Magnetoresistance Measurement. NANO LETTERS 2020; 20:75-80. [PMID: 31820649 DOI: 10.1021/acs.nanolett.9b03110] [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
Localized electronic spin state in molecules has a relatively long spin lifetime and has thus attracted much attention. In this study, we characterize the magnetoresistance of a system comprising Pt and Fe(II)-phthalocyanine (FePc) molecules. The magnetoresistance measurement with the weak antilocalization analysis reveals that a magnetic moment in FePc acts as magnetic impurities for conduction electrons in Pt. Moreover, we find that the magnetoresistance involves a component that possesses the same symmetry as spin-Hall magnetoresistance. These results reveal the spin-angular momentum transfer from metallic Pt to a magnetic moment in FePc molecules, which can be used as a spin torque in a molecular system.
Collapse
Affiliation(s)
- Hiromu Gamou
- Department of Materials Science , Tohoku University , Sendai , Miyagi 980-8579 , Japan
| | - Koki Shimose
- Graduate School of Engineering Science , Osaka University , Toyonaka , Osaka 560-8531 , Japan
| | - Ryoto Enoki
- Department of Materials Science , Tohoku University , Sendai , Miyagi 980-8579 , Japan
| | - Emi Minamitani
- Department of Theoretical and Computational Molecular Science , Institute for Molecular Science , Okazaki , Aichi 444-8585 , Japan
- Department of Materials Engineering , The University of Tokyo , Bunkyo , Tokyo 113-8656 , Japan
| | - Akitoshi Shiotari
- Department of Advanced Materials Science , The University of Tokyo , Kashiwa , Chiba 277-8561 , Japan
| | - Yoshinori Kotani
- Japan Synchrotron Radiation Research Institute , Sayo , Hyogo 679-5198 , Japan
| | - Kentaro Toyoki
- Japan Synchrotron Radiation Research Institute , Sayo , Hyogo 679-5198 , Japan
| | - Tetsuya Nakamura
- Japan Synchrotron Radiation Research Institute , Sayo , Hyogo 679-5198 , Japan
| | - Yoshiaki Sugimoto
- Department of Advanced Materials Science , The University of Tokyo , Kashiwa , Chiba 277-8561 , Japan
| | - Makoto Kohda
- Department of Materials Science , Tohoku University , Sendai , Miyagi 980-8579 , Japan
- Center for Spintronics Research Network , Tohoku University , Sendai , Miyagi 980-8577 , Japan
- Center for Science and Innovation in Spintronics (Core Research Cluster) Organization for Advanced Studies , Tohoku University , Sendai , Miyagi 980-8577 , Japan
| | - Junsaku Nitta
- Department of Materials Science , Tohoku University , Sendai , Miyagi 980-8579 , Japan
- Center for Spintronics Research Network , Tohoku University , Sendai , Miyagi 980-8577 , Japan
- Center for Science and Innovation in Spintronics (Core Research Cluster) Organization for Advanced Studies , Tohoku University , Sendai , Miyagi 980-8577 , Japan
| | - Shinji Miwa
- Graduate School of Engineering Science , Osaka University , Toyonaka , Osaka 560-8531 , Japan
- The Institute for Solid State Physics , The University of Tokyo , Kashiwa , Chiba 277-8581 , Japan
- Center for Spintronics Research Network , Osaka University , Toyonaka , Osaka 560-8531 , Japan
| |
Collapse
|
32
|
Barhoumi R, Amokrane A, Klyatskaya S, Boero M, Ruben M, Bucher JP. Screening the 4f-electron spin of TbPc 2 single-molecule magnets on metal substrates by ligand channeling. NANOSCALE 2019; 11:21167-21179. [PMID: 31663092 DOI: 10.1039/c9nr05873g] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Bis(phthalocyaninato)lanthanide (LnPc2) double-decker-based devices have recently attracted a great deal of interest for data encoding purposes. Although the 4f-electrons of lanthanide ions play a key role in the experimental methodology, their localized character, deeper in energy compared to the 3d electrons of transition metals, hampers a detailed investigation. Here, our approach consists of the follow-up of the entanglement process with other molecules and with the substrate electrons by means of space-resolved detection of the Kondo resonance by scanning tunneling spectroscopy (STS), using different substrates (from weak to strong interaction). It is found that TbPc2 molecules firstly interact with their environment by means of the π-radicals of the ligand. The radical spin of TbPc2 can be identified by STS on a weakly interacting substrate such as Au(111). In the case of a Ag(111) substrate, we are able to analyze the effect of an electron transfer on the molecule (pairing-up of the radical spin) and the subsequent quenching of the Kondo resonance. Finally, on a strongly interacting substrate such as Cu(111), a significant rearrangement of electrons takes place and the Kondo screening of the 4f electrons of the Tb ion of TbPc2 is observed. By comparative STS measurements on YPc2, that has empty 4d and 4f shells, we prove that the Kondo resonance measured in the center of the TbPc2 molecule indeed stems from the 4f-electrons. At the same time, we provide evidence for the hybridization of the 4f states with the π electron.
Collapse
Affiliation(s)
- Rabei Barhoumi
- Université de Strasbourg, CNRS, IPCMS UMR 7504, F-67034 Strasbourg, France.
| | - 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.
| |
Collapse
|
33
|
Guan X, Zhu G, Zhang Y, Cao J. The modulation of the magnetocrystalline anisotropy of the halogen functionalize metal-phthalocyanine networks. Chem Phys Lett 2019. [DOI: 10.1016/j.cplett.2019.05.015] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
|
34
|
Forker R, Gruenewald M, Sojka F, Peuker J, Mueller P, Zwick C, Huempfner T, Meissner M, Fritz T. Fraternal twins: distinction between PbPc and SnPc by their switching behaviour in a scanning tunnelling microscope. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2019; 31:134004. [PMID: 30729922 DOI: 10.1088/1361-648x/aafeae] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
In this contribution, we compare the optical absorbance behaviour and the structural properties of lead(II)-phthalocyanine (PbPc) and tin(II)-phthalocyanine (SnPc) thin films. To this end, we employ a Ag(1 1 1) substrate terminated with a monolayer of 3,4,9,10-perylene tetracarboxylic dianhydride constituting an internal interface whose main effect is an electronic decoupling of the phthalocyanine adlayer from the metal surface. As deduced from low-energy electron diffraction and scanning tunnelling microscopy (STM) measurements, the epitaxial relations and unit cell compositions of the prevailing PbPc monolayer and multilayer domains are confusingly similar to those of SnPc on PTCDA/Ag(1 1 1). However, SnPc and PbPc can be readily distinguished by their STM-induced switching behaviours: while the former is capable of reversible configurational changes, no effect on the latter could be achieved by us under comparable conditions. This corroborates earlier theoretical predictions and even renders the chemical identification of individual shuttlecock-shaped metal-phthalocyanines feasible.
Collapse
Affiliation(s)
- Roman Forker
- Institut für Festkörperphysik, Friedrich-Schiller-Universität Jena, Helmholtzweg 5, 07743 Jena, Germany
| | | | | | | | | | | | | | | | | |
Collapse
|
35
|
Buimaga-Iarinca L, Morari C. The effect of translation on the binding energy for transition-metal porphyrines adsorbed on Ag(111) surface. BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2019; 10:706-717. [PMID: 30931212 PMCID: PMC6423576 DOI: 10.3762/bjnano.10.70] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/17/2018] [Accepted: 02/22/2019] [Indexed: 06/09/2023]
Abstract
The characteristics of interaction between six transition-metal porphyrines and the Ag(111) surface are detailed here as resulted from DFT calculations. Van der Waals interactions as well as the strong correlation in 3d orbitals of transition metals were taken into account in all calculations, including the structural relaxation. For each system we investigate four relative positions of the metallic atom on top the surface. We show that the interaction between the transition metal and silver is the result of a combination between the dispersion interaction, charge transfer and weak chemical interaction. The detailed analysis of the physical properties, such as dipolar and magnetic moments and the molecule-surface charge transfer, analyzed for different geometric configurations allows us to propose qualitative models, relevant for the understanding of the self-assembly processes and related phenomena.
Collapse
Affiliation(s)
- Luiza Buimaga-Iarinca
- National Institute for Research and Development of Isotopic and Molecular Technologies,67-103 Donat, 400293 Cluj-Napoca, Romania
| | - Cristian Morari
- National Institute for Research and Development of Isotopic and Molecular Technologies,67-103 Donat, 400293 Cluj-Napoca, Romania
| |
Collapse
|
36
|
Huttmann F, Rothenbach N, Kraus S, Ollefs K, Arruda LM, Bernien M, Thonig D, Delin A, Fransson J, Kummer K, Brookes NB, Eriksson O, Kuch W, Michely T, Wende H. Europium Cyclooctatetraene Nanowire Carpets: A Low-Dimensional, Organometallic, and Ferromagnetic Insulator. J Phys Chem Lett 2019; 10:911-917. [PMID: 30717591 DOI: 10.1021/acs.jpclett.8b03711] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
We investigate the magnetic and electronic properties of europium cyclooctatetraene (EuCot) nanowires by means of low-temperature X-ray magnetic circular dichroism (XMCD) and scanning tunneling microscopy (STM) and spectroscopy (STS). The EuCot nanowires are prepared in situ on a graphene surface. STS measurements identify EuCot as an insulator with a minority band gap of 2.3 eV. By means of Eu M5,4 edge XMCD, orbital and spin magnetic moments of (-0.1 ± 0.3)μB and (+7.0 ± 0.6)μB, respectively, were determined. Field-dependent measurements of the XMCD signal at the Eu M5 edge show hysteresis for grazing X-ray incidence at 5 K, thus confirming EuCot as a ferromagnetic material. Our density functional theory calculations reproduce the experimentally observed minority band gap. Modeling the experimental results theoretically, we find that the effective interatomic exchange interaction between Eu atoms is on the order of millielectronvolts, that magnetocrystalline anisotropy energy is roughly half as big, and that dipolar energy is approximately ten times lower.
Collapse
Affiliation(s)
- Felix Huttmann
- II. Physikalisches Institut , Universität zu Köln , Zülpicher Strasse 77 , D-50937 Köln , Germany
| | - Nico Rothenbach
- Fakultät für Physik , Universität Duisburg-Essen and Center for Nanointegration Duisburg-Essen (CENIDE) , Lotharstr. 1 , D-47057 Duisburg , Germany
| | - Stefan Kraus
- II. Physikalisches Institut , Universität zu Köln , Zülpicher Strasse 77 , D-50937 Köln , Germany
| | - Katharina Ollefs
- Fakultät für Physik , Universität Duisburg-Essen and Center for Nanointegration Duisburg-Essen (CENIDE) , Lotharstr. 1 , D-47057 Duisburg , Germany
| | - Lucas M Arruda
- Institut für Experimentalphysik , Freie Universität Berlin , Arnimallee 14 , 14195 Berlin , Germany
| | - Matthias Bernien
- Institut für Experimentalphysik , Freie Universität Berlin , Arnimallee 14 , 14195 Berlin , Germany
| | - Danny Thonig
- Department of Physics and Astronomy, Materials Theory , Uppsala University , SE-75120 Uppsala , Sweden
| | - Anna Delin
- Department of Physics and Astronomy, Materials Theory , Uppsala University , SE-75120 Uppsala , Sweden
- Department of Applied Physics, School of Engineering Sciences , KTH Royal Institute of Technology , Electrum 229 , SE-16440 Kista , Sweden
- SeRC (Swedish e-Science Research Center), KTH Royal Institute of Technology , SE-10044 Stockholm , Sweden
| | - Jonas Fransson
- Department of Physics and Astronomy, Materials Theory , Uppsala University , SE-75120 Uppsala , Sweden
| | - Kurt Kummer
- European Synchrotron Radiation Facility , 71 Avenue des Martyrs, CS40220 , F-38043 Grenoble , Cedex 9, France
| | - Nicholas B Brookes
- European Synchrotron Radiation Facility , 71 Avenue des Martyrs, CS40220 , F-38043 Grenoble , Cedex 9, France
| | - Olle Eriksson
- Department of Physics and Astronomy, Materials Theory , Uppsala University , SE-75120 Uppsala , Sweden
- School of Science and Technology , Örebro University , SE-701 82 Örebro , Sweden
| | - Wolfgang Kuch
- Institut für Experimentalphysik , Freie Universität Berlin , Arnimallee 14 , 14195 Berlin , Germany
| | - Thomas Michely
- II. Physikalisches Institut , Universität zu Köln , Zülpicher Strasse 77 , D-50937 Köln , Germany
| | - Heiko Wende
- Fakultät für Physik , Universität Duisburg-Essen and Center for Nanointegration Duisburg-Essen (CENIDE) , Lotharstr. 1 , D-47057 Duisburg , Germany
| |
Collapse
|
37
|
Jo J, Byun J, Oh I, Park J, Jin MJ, Min BC, Lee J, Yoo JW. Molecular Tunability of Magnetic Exchange Bias and Asymmetrical Magnetotransport in Metalloporphyrin/Co Hybrid Bilayers. ACS NANO 2019; 13:894-903. [PMID: 30557507 DOI: 10.1021/acsnano.8b08689] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Individual molecular spins are promising quantum states for emerging computation technologies. The "on surface" configuration of molecules in proximity to a magnetic film allows control over the orientations of molecular spins and coupling between them. The stacking of planar molecular spins could favor antiferromagnetic interlayer couplings and lead to pinning of the magnetic underlayer via the exchange bias, which is extensively utilized in ultrafast and high-density spintronics. However, fundamental understanding of the molecular exchange bias and its operating features on a device has not been unveiled. Here, we showed tunable molecular exchange bias and its asymmetrical magnetotransport characteristics on a device by using the metalloporphyrin/cobalt hybrid films. A series of the distinctive molecular layers showcased a wide range of the interfacial exchange coupling and bias. The transport behaviors of the hybrid bilayer films revealed the molecular exchange bias effect on a fabricated device, representing asymmetric characteristics on anisotropic and angle-dependent magnetoresistances. Theoretical simulations demonstrated close correlations among the interfacial distance, magnetic interaction, and exchange bias. This study of the hybrid interfacial coupling and its impact on magnetic and magnetotransport behaviors will extend functionalities of molecular spinterfaces for emerging information technologies.
Collapse
Affiliation(s)
- Junhyeon Jo
- School of Materials Science and Engineering/Low-Dimensional Carbon Materials Center , Ulsan National Institute of Science and Technology , Ulsan 44919 , Korea
| | - Jinho Byun
- Department of Physics , Pusan National University , Busan 46241 , Korea
| | - Inseon Oh
- School of Materials Science and Engineering/Low-Dimensional Carbon Materials Center , Ulsan National Institute of Science and Technology , Ulsan 44919 , Korea
| | - Jungmin Park
- School of Materials Science and Engineering/Low-Dimensional Carbon Materials Center , Ulsan National Institute of Science and Technology , Ulsan 44919 , Korea
| | - Mi-Jin Jin
- School of Materials Science and Engineering/Low-Dimensional Carbon Materials Center , Ulsan National Institute of Science and Technology , Ulsan 44919 , Korea
| | - Byoung-Chul Min
- Center for Spintronics , Korea Institute of Science and Technology , Seoul 02792 , Korea
| | - Jaekwang Lee
- Department of Physics , Pusan National University , Busan 46241 , Korea
| | - Jung-Woo Yoo
- School of Materials Science and Engineering/Low-Dimensional Carbon Materials Center , Ulsan National Institute of Science and Technology , Ulsan 44919 , Korea
| |
Collapse
|
38
|
Interfacial Spin Manipulation of Nickel-Quinonoid Complex Adsorbed on Co(001) Substrate. MAGNETOCHEMISTRY 2018. [DOI: 10.3390/magnetochemistry5010002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
We studied the structural, electronic, and magnetic properties of a recently synthesized Ni(II)-quinonoid complex upon adsorption on a magnetic Co(001) substrate. Our density functional theory + U (DFT+U) calculations predict that the molecule undergoes a spin-state switching from low-spin S = 0 in the gas phase to high-spin S ≈ 1 when adsorbed on the Co(001) surface. A strong covalent interaction of the quinonoid rings and surface atoms leads to an increase of the Ni–O(N) bond lengths in the chemisorbed molecule that support the spin-state switching. Our DFT+U calculations show that the molecule is ferromagnetically coupled to the substrate. The Co surface–Ni center exchange mechanism was carefully investigated. We identified an indirect exchange interaction via the quinonoid ligands that stabilizes the molecule’s spin moment in ferromagnetic alignment with the Co surface magnetization.
Collapse
|
39
|
Guo M, Källman E, Pinjari RV, Couto RC, Kragh Sørensen L, Lindh R, Pierloot K, Lundberg M. Fingerprinting Electronic Structure of Heme Iron by Ab Initio Modeling of Metal L-Edge X-ray Absorption Spectra. J Chem Theory Comput 2018; 15:477-489. [DOI: 10.1021/acs.jctc.8b00658] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Affiliation(s)
- Meiyuan Guo
- Department of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, China
- Department of Chemistry - Ångström Laboratory, Uppsala University, 751 20 Uppsala, Sweden
| | - Erik Källman
- Department of Chemistry - Ångström Laboratory, Uppsala University, 751 20 Uppsala, Sweden
| | - Rahul V. Pinjari
- School of Chemical Sciences, Swami Ramanand Teerth Marathwada University, Nanded 431606, Maharashtra, India
| | - Rafael C. Couto
- Department of Chemistry - Ångström Laboratory, Uppsala University, 751 20 Uppsala, Sweden
| | - Lasse Kragh Sørensen
- Department of Chemistry - Ångström Laboratory, Uppsala University, 751 20 Uppsala, Sweden
| | - Roland Lindh
- Department of Chemistry - Ångström Laboratory, Uppsala University, 751 20 Uppsala, Sweden
| | - Kristine Pierloot
- Department of Chemistry, University of Leuven, Celestijnenlaan 200F, B-3001 Heverlee Leuven, Belgium
| | - Marcus Lundberg
- Department of Chemistry - Ångström Laboratory, Uppsala University, 751 20 Uppsala, Sweden
- Department of Biotechnology, Chemistry and Pharmacy, Università di Siena, Via A. Moro 2, 53100 Siena, Italy
| |
Collapse
|
40
|
Rolf D, Lotze C, Czekelius C, Heinrich BW, Franke KJ. Visualizing Intramolecular Distortions as the Origin of Transverse Magnetic Anisotropy. J Phys Chem Lett 2018; 9:6563-6567. [PMID: 30384611 DOI: 10.1021/acs.jpclett.8b03036] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The magnetic properties of metal-organic complexes are strongly influenced by conformational changes in the ligand. The flexibility of Fe-tetra-pyridyl-porphyrin molecules leads to different adsorption configurations on a Au(111) surface. By combining low-temperature scanning tunneling spectroscopy and atomic force microscopy, we resolve a correlation of the molecular configuration with different spin states and magnitudes of magnetic anisotropy. When the macrocycle exhibits a laterally undistorted saddle shape, the molecules lie in a S = 1 state with axial anisotropy arising from a square-planar ligand field. If the symmetry in the molecular ligand field is reduced by a lateral distortion of the molecule, we find a finite contribution of transverse anisotropy. Some of the distorted molecules lie in a S = 2 state, again exhibiting substantial transverse anisotropy.
Collapse
Affiliation(s)
- Daniela Rolf
- Fachbereich Physik , Freie Universität Berlin , 14195 Berlin , Germany
| | - Christian Lotze
- Fachbereich Physik , Freie Universität Berlin , 14195 Berlin , Germany
| | - Constantin Czekelius
- Institut für Organische Chemie und Makromolekulare Chemie , Heinrich-Heine-Universität Düsseldorf , 40225 Düsseldorf , Germany
| | | | | |
Collapse
|
41
|
Nachtigallová D, Antalík A, Lo R, Sedlák R, Manna D, Tuček J, Ugolotti J, Veis L, Legeza Ö, Pittner J, Zbořil R, Hobza P. An Isolated Molecule of Iron(II) Phthalocyanin Exhibits Quintet Ground-State: A Nexus between Theory and Experiment. Chemistry 2018; 24:13413-13417. [DOI: 10.1002/chem.201803380] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2018] [Revised: 07/31/2018] [Indexed: 01/07/2023]
Affiliation(s)
- Dana Nachtigallová
- Institute of Organic Chemistry and Biochemistry; Academy of Sciences of the Czech Republic; v.v.i., Flemingovo nám. 2 16610 Prague 6 Czech Republic
- Regional Centre of Advanced Technologies and Materials; Department of Physical Chemistry; Faculty of Science, Palacký University in Olomouc; Šlechtitelů 27 78371 Olomouc Czech Republic
| | - Andrej Antalík
- J. Heyrovský Institute of Physical Chemistry; Academy of Sciences of the Czech Republic; v.v.i., Dolejškova 3 18223 Prague 8 Czech Republic
- Faculty of Mathematics and Physics; Charles University Prague; 11636 Prague Czech Republic Republic
| | - Rabindranath Lo
- Institute of Organic Chemistry and Biochemistry; Academy of Sciences of the Czech Republic; v.v.i., Flemingovo nám. 2 16610 Prague 6 Czech Republic
- Regional Centre of Advanced Technologies and Materials; Department of Physical Chemistry; Faculty of Science, Palacký University in Olomouc; Šlechtitelů 27 78371 Olomouc Czech Republic
| | - Robert Sedlák
- Institute of Organic Chemistry and Biochemistry; Academy of Sciences of the Czech Republic; v.v.i., Flemingovo nám. 2 16610 Prague 6 Czech Republic
- Regional Centre of Advanced Technologies and Materials; Department of Physical Chemistry; Faculty of Science, Palacký University in Olomouc; Šlechtitelů 27 78371 Olomouc Czech Republic
| | - Debashree Manna
- Institute of Organic Chemistry and Biochemistry; Academy of Sciences of the Czech Republic; v.v.i., Flemingovo nám. 2 16610 Prague 6 Czech Republic
- Regional Centre of Advanced Technologies and Materials; Department of Physical Chemistry; Faculty of Science, Palacký University in Olomouc; Šlechtitelů 27 78371 Olomouc Czech Republic
| | - Jiří Tuček
- Regional Centre of Advanced Technologies and Materials; Department of Physical Chemistry; Faculty of Science, Palacký University in Olomouc; Šlechtitelů 27 78371 Olomouc Czech Republic
| | - Juri Ugolotti
- Regional Centre of Advanced Technologies and Materials; Department of Physical Chemistry; Faculty of Science, Palacký University in Olomouc; Šlechtitelů 27 78371 Olomouc Czech Republic
| | - Libor Veis
- J. Heyrovský Institute of Physical Chemistry; Academy of Sciences of the Czech Republic; v.v.i., Dolejškova 3 18223 Prague 8 Czech Republic
| | - Örs Legeza
- Strongly Correlated Systems “ Lendület” Research group; Wigner Research Centre for Physics; 1525 Budapest Hungary
| | - Jiří Pittner
- J. Heyrovský Institute of Physical Chemistry; Academy of Sciences of the Czech Republic; v.v.i., Dolejškova 3 18223 Prague 8 Czech Republic
| | - Radek Zbořil
- Regional Centre of Advanced Technologies and Materials; Department of Physical Chemistry; Faculty of Science, Palacký University in Olomouc; Šlechtitelů 27 78371 Olomouc Czech Republic
| | - Pavel Hobza
- Institute of Organic Chemistry and Biochemistry; Academy of Sciences of the Czech Republic; v.v.i., Flemingovo nám. 2 16610 Prague 6 Czech Republic
- Regional Centre of Advanced Technologies and Materials; Department of Physical Chemistry; Faculty of Science, Palacký University in Olomouc; Šlechtitelů 27 78371 Olomouc Czech Republic
| |
Collapse
|
42
|
Balinski K, Schneider L, Wöllermann J, Buling A, Joly L, Piamonteze C, Feltham HLC, Brooker S, Powell AK, Delley B, Kuepper K. Element specific determination of the magnetic properties of two macrocyclic tetranuclear 3d-4f complexes with a Cu 3Tb core by means of X-ray magnetic circular dichroism (XMCD). Phys Chem Chem Phys 2018; 20:21286-21293. [PMID: 29922775 DOI: 10.1039/c7cp08689j] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We apply X-ray magnetic circular dichroism to study the internal magnetic structure of two very promising star shaped macrocyclic complexes with a CuII3TbIII core. These complexes are rare examples prepared with a macrocyclic ligand that show indications of SMM (Single Molecule Magnet) behavior, and they differ only in ring size: one has a propylene linked macrocycle, [CuII3TbIII(LPr)(NO3)2(MeOH)(H2O)2](NO3)·3H2O (nickname: Cu3Tb(LPr)), and the other has the butylene linked analogue, [CuII3TbIII(LBu)(NO3)2(MeOH)(H2O)](NO3)·3H2O (nickname: Cu3Tb(LBu)). We analyze the orbital and spin contributions to the Cu and Tb ions quantitatively by applying the spin and orbital sum rules concerning the L2 (M4)/L3 (M5) edges. In combination with appropriate ligand field simulations, we demonstrate that the Tb(iii) ions contribute with high orbital magnetic moments to the magnetic anisotropy, whereas the ligand field determines the easy axis of magnetization. Furthermore, we confirm that the Cu(ii) ions in both molecules are in a divalent valence state, the magnetic moments of the three Cu ions appear to be canted due to 3d-3d intramolecular magnetic interactions. For Cu3Tb(LPr), the corresponding element specific magnetization loops reflect that the Cu(ii) contribution to the overall magnetic picture becomes more important as the temperature is lowered. This implies a low value for the 3d-4f coupling.
Collapse
Affiliation(s)
- K Balinski
- Fachbereich Physik and Institut für Physik und Chemie neuer Materialien, Universität Osnabrück, Barbarastr. 7, Osnabrück D-49069, Germany.
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
43
|
Boukari S, Jabbar H, Schleicher F, Gruber M, Avedissian G, Arabski J, Da Costa V, Schmerber G, Rengasamy P, Vileno B, Weber W, Bowen M, Beaurepaire E. Disentangling Magnetic Hardening and Molecular Spin Chain Contributions to Exchange Bias in Ferromagnet/Molecule Bilayers. NANO LETTERS 2018; 18:4659-4663. [PMID: 29991266 DOI: 10.1021/acs.nanolett.8b00570] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We performed ferromagnetic resonance and magnetometry experiments to clarify the relationship between two reported magnetic exchange effects arising from interfacial spin-polarized charge transfer in ferromagnetic metal (FM)/molecule bilayers: the magnetic hardening effect and spinterface-stabilized molecular spin chains. To disentangle these effects, we tuned the metal phthalocyanine molecule central site's magnetic moment to enhance or suppress the formation of spin chains in the molecular film. We find that both effects are distinct, and additive. In the process, we extend the list of FM/molecule candidate pairs that are known to generate magnetic exchange effects, experimentally confirm the predicted increase in anisotropy upon molecular adsorption, and show that spin chains within the molecular film can enhance magnetic exchange. Our results confirm, as an echo to progress regarding inorganic spintronic tunnelling, that spintronic tunnelling across structurally ordered organic barriers has been reached through previous magnetotransport experiments.
Collapse
Affiliation(s)
- Samy Boukari
- Institut de Physique et Chimie des Matériaux de Strasbourg, Université de Strasbourg, CNRS UMR 7504 , 23 rue du Loess, BP 43 , F-67034 Strasbourg Cedex 2 , France
| | - Hashim Jabbar
- Institut de Physique et Chimie des Matériaux de Strasbourg, Université de Strasbourg, CNRS UMR 7504 , 23 rue du Loess, BP 43 , F-67034 Strasbourg Cedex 2 , France
| | - Filip Schleicher
- Institut de Physique et Chimie des Matériaux de Strasbourg, Université de Strasbourg, CNRS UMR 7504 , 23 rue du Loess, BP 43 , F-67034 Strasbourg Cedex 2 , France
| | - Manuel Gruber
- Institut de Physique et Chimie des Matériaux de Strasbourg, Université de Strasbourg, CNRS UMR 7504 , 23 rue du Loess, BP 43 , F-67034 Strasbourg Cedex 2 , France
| | - Garen Avedissian
- Institut de Physique et Chimie des Matériaux de Strasbourg, Université de Strasbourg, CNRS UMR 7504 , 23 rue du Loess, BP 43 , F-67034 Strasbourg Cedex 2 , France
| | - Jacek Arabski
- Institut de Physique et Chimie des Matériaux de Strasbourg, Université de Strasbourg, CNRS UMR 7504 , 23 rue du Loess, BP 43 , F-67034 Strasbourg Cedex 2 , France
| | - Victor Da Costa
- Institut de Physique et Chimie des Matériaux de Strasbourg, Université de Strasbourg, CNRS UMR 7504 , 23 rue du Loess, BP 43 , F-67034 Strasbourg Cedex 2 , France
| | - Guy Schmerber
- Institut de Physique et Chimie des Matériaux de Strasbourg, Université de Strasbourg, CNRS UMR 7504 , 23 rue du Loess, BP 43 , F-67034 Strasbourg Cedex 2 , France
| | - Prashanth Rengasamy
- Institut de Physique et Chimie des Matériaux de Strasbourg, Université de Strasbourg, CNRS UMR 7504 , 23 rue du Loess, BP 43 , F-67034 Strasbourg Cedex 2 , France
| | - Bertrand Vileno
- Institut de Chimie de Strasbourg, Université de Strasbourg, CNRS UMR7177 , 4 rue Blaise Pascal , F-67081 Strasbourg Cedex , France
- French EPR Federation of Research (REseau NAtional de Rpe interDisciplinaire (RENARD), Fédération IR-RPE CNRS 3443) , 59655 Villeneuve d'Ascq Cedex , France
| | - Wolfgang Weber
- Institut de Physique et Chimie des Matériaux de Strasbourg, Université de Strasbourg, CNRS UMR 7504 , 23 rue du Loess, BP 43 , F-67034 Strasbourg Cedex 2 , France
| | - Martin Bowen
- Institut de Physique et Chimie des Matériaux de Strasbourg, Université de Strasbourg, CNRS UMR 7504 , 23 rue du Loess, BP 43 , F-67034 Strasbourg Cedex 2 , France
| | - Eric Beaurepaire
- Institut de Physique et Chimie des Matériaux de Strasbourg, Université de Strasbourg, CNRS UMR 7504 , 23 rue du Loess, BP 43 , F-67034 Strasbourg Cedex 2 , France
| |
Collapse
|
44
|
Wang X, Yang L, Ye L, Zheng X, Yan Y. Precise Control of Local Spin States in an Adsorbed Magnetic Molecule with an STM Tip: Theoretical Insights from First-Principles-Based Simulation. J Phys Chem Lett 2018; 9:2418-2425. [PMID: 29685031 DOI: 10.1021/acs.jpclett.8b00808] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The precise tuning of local spin states in adsorbed organometallic molecules by a mechanically controlled scanning tunneling microscope (STM) tip has become a focus of recent experiments. However, the underlying mechanisms remain somewhat unclear. We investigate theoretically the STM tip control of local spin states in a single iron(II) porphyrin molecule adsorbed on the Pb(111) substrate. A combined density functional theory and hierarchical equations of motion approach is employed to simulate the tip tuning process in conjunction with the complete active space self-consistent field method for accurate computation of magnetic anisotropy. Our first-principles-based simulation accurately reproduces the tuning of magnetic anisotropy realized in experiment. Moreover, we elucidate the evolution of geometric and electronic structures of the composite junction and disclose the delicate competition between the Kondo resonance and local spin excitation. The understanding and insight provided by the first-principles-based simulation may help to realize more fascinating quantum state manipulations.
Collapse
Affiliation(s)
- Xiaoli Wang
- Hefei National Laboratory for Physical Sciences at the Microscale & Synergetic Innovation Center of Quantum Information and Quantum Physics , University of Science and Technology of China , Hefei , Anhui 230026 , China
| | - Longqing Yang
- Hefei National Laboratory for Physical Sciences at the Microscale & Synergetic Innovation Center of Quantum Information and Quantum Physics , University of Science and Technology of China , Hefei , Anhui 230026 , China
| | - LvZhou Ye
- Hefei National Laboratory for Physical Sciences at the Microscale & Synergetic Innovation Center of Quantum Information and Quantum Physics , University of Science and Technology of China , Hefei , Anhui 230026 , China
| | - Xiao Zheng
- Hefei National Laboratory for Physical Sciences at the Microscale & Synergetic Innovation Center of Quantum Information and Quantum Physics , University of Science and Technology of China , Hefei , Anhui 230026 , China
- Guizhou Provincial Key Laboratory of Computational Nano-Material Science, Institute of Applied Physics , Guizhou Normal College , Guiyang , Guizhou 550018 , China
| | - YiJing Yan
- Hefei National Laboratory for Physical Sciences at the Microscale & iChEM , University of Science and Technology of China , Hefei , Anhui 230026 , China
| |
Collapse
|
45
|
Heinrich BW, Ehlert C, Hatter N, Braun L, Lotze C, Saalfrank P, Franke KJ. Control of Oxidation and Spin State in a Single-Molecule Junction. ACS NANO 2018; 12:3172-3177. [PMID: 29489330 DOI: 10.1021/acsnano.8b00312] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The oxidation and spin state of a metal-organic molecule determine its chemical reactivity and magnetic properties. Here, we demonstrate the reversible control of the oxidation and spin state in a single Fe porphyrin molecule in the force field of the tip of a scanning tunneling microscope. Within the regimes of half-integer and integer spin state, we can further track the evolution of the magnetocrystalline anisotropy. Our experimental results are corroborated by density functional theory and wave function theory. This combined analysis allows us to draw a complete picture of the molecular states over a large range of intramolecular deformations.
Collapse
Affiliation(s)
- Benjamin W Heinrich
- Fachbereich Physik , Freie Universität Berlin , Arnimallee 14 , 14195 Berlin , Germany
| | - Christopher Ehlert
- Institute of Chemistry , Universität Potsdam , Karl-Liebknecht-Strasse 24-25 , 14476 Potsdam , Germany
- Department of Chemistry , Wilfrid Laurier University , 75 University Avenue West , Waterloo , Ontario N2L3C5 , Canada
| | - Nino Hatter
- Fachbereich Physik , Freie Universität Berlin , Arnimallee 14 , 14195 Berlin , Germany
| | - Lukas Braun
- Fachbereich Physik , Freie Universität Berlin , Arnimallee 14 , 14195 Berlin , Germany
| | - Christian Lotze
- Fachbereich Physik , Freie Universität Berlin , Arnimallee 14 , 14195 Berlin , Germany
| | - Peter Saalfrank
- Institute of Chemistry , Universität Potsdam , Karl-Liebknecht-Strasse 24-25 , 14476 Potsdam , Germany
| | - Katharina J Franke
- Fachbereich Physik , Freie Universität Berlin , Arnimallee 14 , 14195 Berlin , Germany
| |
Collapse
|
46
|
Avvisati G, Cardoso C, Varsano D, Ferretti A, Gargiani P, Betti MG. Ferromagnetic and Antiferromagnetic Coupling of Spin Molecular Interfaces with High Thermal Stability. NANO LETTERS 2018; 18:2268-2273. [PMID: 29558616 DOI: 10.1021/acs.nanolett.7b04836] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We report an advanced organic spin-interface architecture with magnetic remanence at room temperature, constituted by metal phthalocyanine molecules magnetically coupled with Co layer(s), mediated by graphene. Fe- and Cu-phthalocyanines assembled on graphene/Co have identical structural configurations, but FePc couples antiferromagnetically with Co up to room temperature, while CuPc couples ferromagnetically with weaker coupling and thermal stability, as deduced by element-selective X-ray magnetic circular dichroic signals. The robust antiferromagnetic coupling is stabilized by a superexchange interaction, driven by the out-of-plane molecular orbitals responsible of the magnetic ground state and electronically decoupled from the underlying metal via the graphene layer, as confirmed by ab initio theoretical predictions. These archetypal spin interfaces can be prototypes to demonstrate how antiferromagnetic and/or ferromagnetic coupling can be optimized by selecting the molecular orbital symmetry.
Collapse
Affiliation(s)
- Giulia Avvisati
- Dipartimento di Fisica , Università di Roma "La Sapienza" , I-00185 Roma , Italy
| | - Claudia Cardoso
- Centro S3 , CNR-Istituto Nanoscienze , I-41125 Modena , Italy
| | - Daniele Varsano
- Centro S3 , CNR-Istituto Nanoscienze , I-41125 Modena , Italy
| | - Andrea Ferretti
- Centro S3 , CNR-Istituto Nanoscienze , I-41125 Modena , Italy
| | - Pierluigi Gargiani
- ALBA Synchrotron Light Source, E-08290 Cerdanyola del Valles, Barcelona , Spain
| | - Maria Grazia Betti
- Dipartimento di Fisica , Università di Roma "La Sapienza" , I-00185 Roma , Italy
| |
Collapse
|
47
|
Shao Y, Pang R, Pan H, Shi X. Fullerene/layered antiferromagnetic reconstructed spinterface: Subsurface layer dominates molecular orbitals' spin-split and large induced magnetic moment. J Chem Phys 2018; 148:114704. [PMID: 29566528 DOI: 10.1063/1.5012926] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The interfaces between organic molecules and magnetic metals have gained increasing interest for both fundamental reasons and applications. Among them, the C60/layered antiferromagnetic (AFM) interfaces have been studied only for C60 bonded to the outermost ferromagnetic layer [S. L. Kawahara et al., Nano Lett. 12, 4558 (2012) and D. Li et al., Phys. Rev. B 93, 085425 (2016)]. Here, via density functional theory calculations combined with evidence from the literature, we demonstrate that C60 adsorption can reconstruct the layered-AFM Cr(001) surface at elevated annealing temperatures so that C60 bonds to both the outermost and the subsurface Cr layers in opposite spin directions. Surface reconstruction drastically changes the adsorbed molecule spintronic properties: (1) the spin-split p-d hybridization involves multi-orbitals of C60 and top two layers of Cr with opposite spin-polarization, (2) the subsurface Cr atom dominates the C60 electronic properties, and (3) the reconstruction induces a large magnetic moment of 0.58 μB in C60 as a synergistic effect of the top two Cr layers. The induced magnetic moment in C60 can be explained by the magnetic direct-exchange mechanism, which can be generalized to other C60/magnetic metal systems. Understanding these complex hybridization behaviors is a crucial step for molecular spintronic applications.
Collapse
Affiliation(s)
- Yangfan Shao
- Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
| | - Rui Pang
- International Laboratory of Quantum Functional Materials of Henan and School of Physics and Engineering, Zhengzhou University, Zhengzhou 450001, China
| | - Hui Pan
- Institute of Applied Physics and Materials Engineering, University of Macau, Macau, China
| | - Xingqiang Shi
- Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
| |
Collapse
|
48
|
Moreno Pineda E, Komeda T, Katoh K, Yamashita M, Ruben M. Surface confinement of TbPc 2-SMMs: structural, electronic and magnetic properties. Dalton Trans 2018; 45:18417-18433. [PMID: 27824366 DOI: 10.1039/c6dt03298b] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Since 2003, terbium(iii) bis-phthalocyaninato complexes have been recognised as acting as single molecule magnets (SMMs), propitiating multiple studies with the aim of better understanding the single metal-ion based magnetism with unusually high blocking temperatures. In the quest for novel applications, it became clear that if spintronic devices were made from SMM molecules, their confinement in the proximity of surfaces or electrodes would become difficult to circumvent. In this perspective article, we highlight the influence of the presence of different substrates on the magnetic performance of TbPc2-SMMs, in principle caused by, among other effects, electronic hybridization, dipole-dipole coupling and changing quantum tunnelling (QT) rates on the surface. We show that the improved comprehension of how SMMs interact and communicate with the environment finally leads to magnetic remanence and lower tunnelling rates, paving the way to novel classes of spintronic devices.
Collapse
Affiliation(s)
- Eufemio Moreno Pineda
- Institute of Nanotechnology (INT), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, D-76344 Eggenstein-Leopoldshafen, Germany.
| | - Tadahiro Komeda
- Institute of Multidisciplinary Research for Advanced Materials (IMRAM, Tagen), Tohoku University, Japan
| | - Keiichi Katoh
- Department of Chemistry, Graduate School of Science, Tohoku University, Aramaki-Aza-Aoba, Aoba-Ku, Sendai 980-8578, Japan.
| | - Masahiro Yamashita
- Department of Chemistry, Graduate School of Science, Tohoku University, Aramaki-Aza-Aoba, Aoba-Ku, Sendai 980-8578, Japan. and WPI Research Center, Advanced Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan
| | - Mario Ruben
- Institute of Nanotechnology (INT), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, D-76344 Eggenstein-Leopoldshafen, Germany. and WPI Research Center, Advanced Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan and Institut de Physique et Chimie des Matériaux de Strasbourg (IPCMS), CNRS-Université de Strasbourg, 23 rue du Loess, BP 43, F-67034 Strasbourg Cedex 2, France
| |
Collapse
|
49
|
Corradini V, Candini A, Klar D, Biagi R, De Renzi V, Lodi Rizzini A, Cavani N, Del Pennino U, Klyatskaya S, Ruben M, Velez-Fort E, Kummer K, Brookes NB, Gargiani P, Wende H, Affronte M. Probing magnetic coupling between LnPc 2 (Ln = Tb, Er) molecules and the graphene/Ni (111) substrate with and without Au-intercalation: role of the dipolar field. NANOSCALE 2017; 10:277-283. [PMID: 29210429 DOI: 10.1039/c7nr06610d] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Lanthanides (Ln) bis-phthalocyanine (Pc), the so-called LnPc2double decker, are a promising class of molecules with a well-defined magnetic anisotropy. In this work, we investigate the magnetic properties of LnPc2 molecules UHV-deposited on a graphene/Ni(111) substrate and how they modify when an Au layer is intercalated between Ni and graphene. X-ray absorption spectroscopy (XAS), and linear and magnetic circular dichroism (XLD and XMCD) were used to characterize the systems and probe the magnetic coupling between LnPc2 molecules and the Ni substrate through graphene, both gold-intercalated and not. Two types of LnPc2 molecules (Ln = Tb, Er) with a different magnetic anisotropy (easy-axis for Tb, easy-plane for Er) were considered. XMCD shows an antiferromagnetic coupling between Ln and Ni(111) even in the presence of the graphene interlayer. Au intercalation causes the vanishing of the interaction between Tb and Ni(111). In contrast, in the case of ErPc2, we found that the gold intercalation does not perturb the magnetic coupling. These results, combined with the magnetic anisotropy of the systems, suggest the possible importance of the magnetic dipolar field contribution for determining the magnetic behaviour.
Collapse
Affiliation(s)
- V Corradini
- Centro S3, Istituto Nanoscienze - CNR, via G. Campi 213/A, 41125 Modena, Italy.
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
50
|
Controlled spin switching in a metallocene molecular junction. Nat Commun 2017; 8:1974. [PMID: 29215014 PMCID: PMC5719446 DOI: 10.1038/s41467-017-02151-6] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2017] [Accepted: 11/09/2017] [Indexed: 12/01/2022] Open
Abstract
The active control of a molecular spin represents one of the main challenges in molecular spintronics. Up to now spin manipulation has been achieved through the modification of the molecular structure either by chemical doping or by external stimuli. However, the spin of a molecule adsorbed on a surface depends primarily on the interaction between its localized orbitals and the electronic states of the substrate. Here we change the effective spin of a single molecule by modifying the molecule/metal interface in a controlled way using a low-temperature scanning tunneling microscope. A nickelocene molecule reversibly switches from a spin 1 to 1/2 when varying the electrode–electrode distance from tunnel to contact regime. This switching is experimentally evidenced by inelastic and elastic spin-flip mechanisms observed in reproducible conductance measurements and understood using first principle calculations. Our work demonstrates the active control over the spin state of single molecule devices through interface manipulation. Manipulating spin states of molecules in a controllable manner is essential to develop the molecule-based spintronics technologies. Here, Ormaza et al. show how to use the interaction between a single metallocene molecule and a metallic surface to reversibly switch spin from 1 to ½ in a junction.
Collapse
|