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Lawes P, Boero M, Barhoumi R, Klyatskaya S, Ruben M, Bucher JP. Hierarchical Self-Assembly and Conformation of Tb Double-Decker Molecular Magnets: Experiment and Molecular Dynamics. Nanomaterials (Basel) 2023; 13:2232. [PMID: 37570550 PMCID: PMC10421050 DOI: 10.3390/nano13152232] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2023] [Revised: 07/24/2023] [Accepted: 07/31/2023] [Indexed: 08/13/2023]
Abstract
Nanostructures, fabricated by locating molecular building blocks in well-defined positions, for example, on a lattice, are ideal platforms for studying atomic-scale quantum effects. In this context, STM data obtained from self-assembled Bis(phthalocyaninato) Terbium (III) (TbPc2) single-molecule magnets on various substrates have raised questions about the conformation of the TbPc2 molecules within the lattice. In order to address this issue, molecular dynamics simulations were carried out on a 2D assembly of TbPc2 molecules. The calculations are in excellent agreement with the experiment, and thus improve our understanding of the self-assembly process. In particular, the calculated electron density of the molecular assembly compares well with STM contrast of self-assembled TbPc2 on Au(111), simultaneously providing the conformation of the two Pc ligands of the individual double-decker molecule. This approach proves valuable in the identification of the STM contrast of LnPc2 layers and could be used in similar cases where it is difficult to interpret the STM images of an assembly of molecular complexes.
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Affiliation(s)
- Patrick Lawes
- Institut de Physique et de Chimie de Matériaux (IPCMS), Université de Strasbourg, UMR 7504, F-67034 Strasbourg, France; (P.L.); (M.B.); (R.B.)
- Institute of Nanotechnology and Institute of Quantum Materials and Technology (IQMT), Karlsruhe Institute of Technology, 76131 Karlsruhe, Germany; (S.K.); (M.R.)
| | - Mauro Boero
- Institut de Physique et de Chimie de Matériaux (IPCMS), Université de Strasbourg, UMR 7504, F-67034 Strasbourg, France; (P.L.); (M.B.); (R.B.)
| | - Rabei Barhoumi
- Institut de Physique et de Chimie de Matériaux (IPCMS), Université de Strasbourg, UMR 7504, F-67034 Strasbourg, France; (P.L.); (M.B.); (R.B.)
- Institute of Nanotechnology and Institute of Quantum Materials and Technology (IQMT), Karlsruhe Institute of Technology, 76131 Karlsruhe, Germany; (S.K.); (M.R.)
| | - Svetlana Klyatskaya
- Institute of Nanotechnology and Institute of Quantum Materials and Technology (IQMT), Karlsruhe Institute of Technology, 76131 Karlsruhe, Germany; (S.K.); (M.R.)
| | - Mario Ruben
- Institute of Nanotechnology and Institute of Quantum Materials and Technology (IQMT), Karlsruhe Institute of Technology, 76131 Karlsruhe, Germany; (S.K.); (M.R.)
- Centre Européen de Science Quantique (CESQ), Institut de Science et d’Ingénierie Supramoléculaires (ISIS), Université de Strasbourg, F-67083 Strasbourg, France
| | - Jean-Pierre Bucher
- Institut de Physique et de Chimie de Matériaux (IPCMS), Université de Strasbourg, UMR 7504, F-67034 Strasbourg, France; (P.L.); (M.B.); (R.B.)
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Varade V, Haider G, Slobodeniuk A, Korytar R, Novotny T, Holy V, Miksatko J, Plsek J, Sykora J, Basova M, Zacek M, Hof M, Kalbac M, Vejpravova J. Chiral Light Emission from a Hybrid Magnetic Molecule-Monolayer Transition Metal Dichalcogenide Heterostructure. ACS Nano 2023; 17:2170-2181. [PMID: 36652711 PMCID: PMC10017025 DOI: 10.1021/acsnano.2c08320] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/19/2022] [Accepted: 01/13/2023] [Indexed: 06/17/2023]
Abstract
Hybrid layered materials assembled from atomically thin crystals and small molecules bring great promises in pushing the current information and quantum technologies beyond the frontiers. We demonstrate here a class of layered valley-spin hybrid (VSH) materials composed of a monolayer two-dimensional (2D) semiconductor and double-decker single molecule magnets (SMMs). We have materialized a VSH prototype by thermal evaporation of terbium bis-phthalocyanine onto a MoS2 monolayer and revealed its composition and stability by both microscopic and spectroscopic probes. The interaction of the VSH components gives rise to the intersystem crossing of the photogenerated carriers and moderate p-doping of the MoS2 monolayer, as corroborated by the density functional theory calculations. We further explored the valley contrast by helicity-resolved photoluminescence (PL) microspectroscopy carried out down to liquid helium temperatures and in the presence of the external magnetic field. The most striking feature of the VSH is the enhanced A exciton-related valley emission observed at the out-of-resonance condition at room temperature, which we elucidated by the proposed nonradiative energy drain transfer mechanism. Our study thus demonstrates the experimental feasibility and great promises of the ultrathin VSH materials with chiral light emission, operable by physical fields for emerging opto-spintronic, valleytronic, and quantum information concepts.
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Affiliation(s)
- Vaibhav Varade
- Department
of Condensed Matter Physics, Faculty of Mathematics and Physics, Charles University, Ke Karlovu 5, 121
16Prague 2, Czech
Republic
| | - Golam Haider
- J.
Heyrovsky Institute of Physical Chemistry, Dolejskova 3, 182
23Prague 8, Czech
Republic
| | - Artur Slobodeniuk
- Department
of Condensed Matter Physics, Faculty of Mathematics and Physics, Charles University, Ke Karlovu 5, 121
16Prague 2, Czech
Republic
| | - Richard Korytar
- Department
of Condensed Matter Physics, Faculty of Mathematics and Physics, Charles University, Ke Karlovu 5, 121
16Prague 2, Czech
Republic
| | - Tomas Novotny
- Department
of Condensed Matter Physics, Faculty of Mathematics and Physics, Charles University, Ke Karlovu 5, 121
16Prague 2, Czech
Republic
| | - Vaclav Holy
- Department
of Condensed Matter Physics, Faculty of Mathematics and Physics, Charles University, Ke Karlovu 5, 121
16Prague 2, Czech
Republic
| | - Jiri Miksatko
- J.
Heyrovsky Institute of Physical Chemistry, Dolejskova 3, 182
23Prague 8, Czech
Republic
| | - Jan Plsek
- J.
Heyrovsky Institute of Physical Chemistry, Dolejskova 3, 182
23Prague 8, Czech
Republic
| | - Jan Sykora
- J.
Heyrovsky Institute of Physical Chemistry, Dolejskova 3, 182
23Prague 8, Czech
Republic
| | - Miriam Basova
- Department
of Condensed Matter Physics, Faculty of Mathematics and Physics, Charles University, Ke Karlovu 5, 121
16Prague 2, Czech
Republic
| | - Martin Zacek
- Department
of Condensed Matter Physics, Faculty of Mathematics and Physics, Charles University, Ke Karlovu 5, 121
16Prague 2, Czech
Republic
| | - Martin Hof
- J.
Heyrovsky Institute of Physical Chemistry, Dolejskova 3, 182
23Prague 8, Czech
Republic
| | - Martin Kalbac
- J.
Heyrovsky Institute of Physical Chemistry, Dolejskova 3, 182
23Prague 8, Czech
Republic
| | - Jana Vejpravova
- Department
of Condensed Matter Physics, Faculty of Mathematics and Physics, Charles University, Ke Karlovu 5, 121
16Prague 2, Czech
Republic
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3
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Huang Y, Zhang Q, Li YC, Yao Y, Hu Y, Ren S. Chemical Tuning Meets 2D Molecular Magnets. Adv Mater 2023; 35:e2208919. [PMID: 36353899 DOI: 10.1002/adma.202208919] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Revised: 11/04/2022] [Indexed: 06/16/2023]
Abstract
2D magnets provoke a surge of interest in large anisotropy in reduced dimensions and are promising for next-generation information technology where dynamic magnetic tuning is essential. Until recently, the crucial metal-organic magnet Cr(pyz)2 ·xLiCl·yTHF with considerable high coercivity and high-temperature magnetic order opens up a new platform to control magnetism in metal-organic materials at room temperature. Here, an in-situ chemical tuning route is reported to realize the controllable transformation of low-temperature magnetic order into room-temperature hard magnetism in Cr(pyz)2 ·xLiCl·yTHF. The chemical tuning via electrochemical lithiation and solvation/desolvation exhibits continuously variable magnetic features from cryogenic magnetism to the room-temperature optimum performance of coercivity (Hc ) of 8500 Oe and energy product of 0.6 MGOe. Such chemically flexible tunability of room-temperature magnetism is ascribed to the different degrees of lithiation and solvation that modify the stoichiometry and Cr-pyrazine coordination framework. Furthermore, the additively manufactured hybrid magnets show air stability and electromagnetic induction, providing potential applications. The findings here suggest chemical tuning as a universal approach to control the anisotropy and magnetism of 2D hybrid magnets at room temperature, promising for data storage, magnetic refrigeration, and spintronics.
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Affiliation(s)
- Yulong Huang
- Department of Mechanical and Aerospace Engineering, University at Buffalo, The State University of New York, Buffalo, NY, 14260, USA
| | - Qiang Zhang
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Yuguang C Li
- Department of Chemistry, University at Buffalo, The State University of New York, Buffalo, NY, 14260, USA
| | - Yu Yao
- Department of Chemistry, University at Buffalo, The State University of New York, Buffalo, NY, 14260, USA
| | - Yong Hu
- Department of Mechanical and Aerospace Engineering, University at Buffalo, The State University of New York, Buffalo, NY, 14260, USA
| | - Shenqiang Ren
- Department of Mechanical and Aerospace Engineering, University at Buffalo, The State University of New York, Buffalo, NY, 14260, USA
- Department of Chemistry, University at Buffalo, The State University of New York, Buffalo, NY, 14260, USA
- Research and Education in Energy, Environment, and Water (RENEW) Institute, University at Buffalo, The State University of New York, Buffalo, NY, 14260, USA
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Zayakin I, Tretyakov E, Akyeva A, Syroeshkin M, Burykina J, Dmitrenok A, Korlyukov A, Nasyrova D, Bagryanskaya I, Stass D, Ananikov V. Overclocking Nitronyl Nitroxide Gold Derivatives in Cross-Coupling Reactions. Chemistry 2023; 29:e202203118. [PMID: 36259387 DOI: 10.1002/chem.202203118] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Indexed: 12/12/2022]
Abstract
Nitronyl nitroxides are functional building blocks in cutting-edge research fields, such as the design of molecular magnets, the development of redox and photoswitchable molecular systems and the creation of redox-active components for organic and hybrid batteries. The key importance of the nitronyl nitroxide function is to translate molecular-level-optimized structures into nano-scale devices and new technologies. In spite of great importance, efficient and versatile synthetic approaches to these compounds still represent a challenge. Particularly, methods for the direct introduction of a nitronyl nitroxide moiety into aromatic systems possess many limitations. Here, we report gold derivatives of nitronyl nitroxide that can enter Pd(0)-catalysed cross-coupling reactions with various aryl bromides, affording the corresponding functionalized nitronyl nitroxides. Based on the high thermal stability and enhanced reactivity in catalytic transformation, a new reagent is suggested for the synthesis of radical systems via a universal cross-coupling approach.
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Affiliation(s)
- Igor Zayakin
- N. D. Zelinsky Institute of Organic Chemistry, 47 Leninsky Prosp., 119991, Moscow, Russia
| | - Evgeny Tretyakov
- N. D. Zelinsky Institute of Organic Chemistry, 47 Leninsky Prosp., 119991, Moscow, Russia
| | - Anna Akyeva
- N. D. Zelinsky Institute of Organic Chemistry, 47 Leninsky Prosp., 119991, Moscow, Russia
| | - Mikhail Syroeshkin
- N. D. Zelinsky Institute of Organic Chemistry, 47 Leninsky Prosp., 119991, Moscow, Russia
| | - Julia Burykina
- N. D. Zelinsky Institute of Organic Chemistry, 47 Leninsky Prosp., 119991, Moscow, Russia
| | - Andrey Dmitrenok
- N. D. Zelinsky Institute of Organic Chemistry, 47 Leninsky Prosp., 119991, Moscow, Russia
| | - Alexander Korlyukov
- A. N. Nesmeyanov Institute of Organoelement Compounds, 28 Vavilov Str., 119991, Moscow, Russia
| | - Darina Nasyrova
- N. D. Zelinsky Institute of Organic Chemistry, 47 Leninsky Prosp., 119991, Moscow, Russia
| | - Irina Bagryanskaya
- N. N. Vorozhtsov Novosibirsk Institute of Organic Chemistry, 9 Akad. Lavrentyev Prosp., 630090, Novosibirsk, Russia
| | - Dmitri Stass
- V. V. Voevodsky Institute of Chemical Kinetics and Combustion, 3 Institutskaya Str., 630090, Novosibirsk, Russia
| | - Valentine Ananikov
- N. D. Zelinsky Institute of Organic Chemistry, 47 Leninsky Prosp., 119991, Moscow, Russia
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Balatskiy D, Tkachenko I, Malakhova I, Polyakova N, Bratskaya S. Polyethylenimine as a Non-Innocent Ligand for Hexacyanoferrates Immobilization. Molecules 2022; 27. [PMID: 36500581 DOI: 10.3390/molecules27238489] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2022] [Revised: 11/18/2022] [Accepted: 11/25/2022] [Indexed: 12/09/2022] Open
Abstract
To understand how polyethyleneimine (PEI), as a ligand, affects structure and properties of the transition metals hexacyanoferrates (HCFs) immobilized in cross-linked PEI matrix, we have synthesized Cu(II), Zn(II), and Fe(III) HCFs via successive ion-exchange reactions with metal salts and K4[FeII(CN)6] or K3[FeIII(CN)6]. The structure and properties of the obtained materials in comparison with the crystalline HCF analogs were investigated with FT-IR, Mössbauer, and UV-Vis spectroscopy. Complete reduction of Fe(III) to Fe(II) by PEI in HCF(III) was confirmed. When synthesis was performed at pH favoring binding of precursor metal ions by PEI, cyano-bridged hybrids rather than polymer-HCFs composites were formed. Although the obtained hybrids did not demonstrate sorption activity toward cesium ions, known for crystalline HCFs, they are of interest for the other applications. SQUID measurements revealed a significant difference in magnetic properties of PEI-HCFs hybrids in comparison with crystalline HCFs. Due to the Fe(III) to Fe(II) reduction in HCF ions, Cu(II) and Fe(III) HCFs(III) lost the molecular magnets properties in PEI matrix, but magnetic ordering, including ferromagnet-antiferromagnet interactions, was observed in all hybrids over the broad temperature range.
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6
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Chapyshev SV, Korchagin DV, Costa P, Sander W. The powder X-band electron paramagnetic resonance spectroscopy of septet pyridyl-2,4,6-trinitrene. Magn Reson Chem 2022; 60:829-835. [PMID: 35319115 DOI: 10.1002/mrc.5269] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2022] [Revised: 03/14/2022] [Accepted: 03/17/2022] [Indexed: 06/14/2023]
Abstract
The first X-band EPR spectrum containing only non-overlapping signals of septet pyridyl-2,4,6-trinitrene and triplet pyridylnitrenes is reported. This spectrum was recorded after photolysis of 2,4,6-triazidopyridine in solid argon at 5 K. The zero-field splitting (ZFS) parameters of this trinitrene as well as of intermediate triplet mononitrenes and quintet dinitrenes formed at early stages of the photolysis were determined using the combination of modern computer line-shape spectral simulations and density functional theory (DFT) calculations. It was found that septet pyridyl-2,4,6-trinitrene has the record negative parameter DS = -0.1031 cm-1 among all known to date septet pyridyl-2,4,6-trinitrenes and may be of interest as a model multi-qubit spin system for investigations of quantum computation processing.
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Affiliation(s)
- Sergei V Chapyshev
- Institute of Problems of Chemical Physics, Russian Academy of Sciences, Chernogolovka, Russian Federation
- Lehrstuhl für Organische Chemie II, Ruhr-Universität, Bochum, Germany
| | - Denis V Korchagin
- Institute of Problems of Chemical Physics, Russian Academy of Sciences, Chernogolovka, Russian Federation
| | - Paulo Costa
- Lehrstuhl für Organische Chemie II, Ruhr-Universität, Bochum, Germany
| | - Wolfram Sander
- Lehrstuhl für Organische Chemie II, Ruhr-Universität, Bochum, Germany
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Kartal S, Rogez G, Robert J, Heinrich B, Boudalis A. A magnetocaloric glass from an ionic-liquid gadolinium complex. Chemphyschem 2022; 23:e202200213. [PMID: 35441760 DOI: 10.1002/cphc.202200213] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Revised: 04/08/2022] [Indexed: 11/09/2022]
Abstract
[Gd 5 (L) 16 (H 2 O) 8 ](Tf 2 N) 15 was obtained from reaction of Gd 2 O 3 with 1-carboxymethyl-3-ethylimidazolium chloride (LHCl). The material was found to be an ionic liquid that freezes to glassy state on cooling to -30°C. Variable-temperature magnetic studies reveal the presence of weak magnetic intramolecular interactions in the glass. Isothermal variable-field magnetization demonstrates a magnetocaloric effect (MCE), which is the first finding of such an effect in a molecular glass. This MCE explainable by an uncoupled representation, with a magnetic entropy change of -11.36 J K -1 kg -1 at 1.8 K for a 0-7 T magnetic field change, and with a refrigerant capacity of 125.9 J kg -1 , in the 1.8-50 K interval.
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Affiliation(s)
- Seda Kartal
- Université de Strasbourg: Universite de Strasbourg, UMR7177: Institut de Chimie de Strasbourg, FRANCE
| | - Guillaume Rogez
- IPCMS: Institut de physique et chimie des materiaux de Strasbourg, IPCMS: Institut de physique et chimie des materiaux de Strasbourg, FRANCE
| | - Jérôme Robert
- IPCMS: Institut de physique et chimie des materiaux de Strasbourg, IPCMS: Institut de physique et chimie des materiaux de Strasbourg, FRANCE
| | - Benoît Heinrich
- IPCMS: Institut de physique et chimie des materiaux de Strasbourg, IPCMS: Institut de physique et chimie des materiaux de Strasbourg, FRANCE
| | - Athanassios Boudalis
- Institut de Chimie de Strasbourg, 4 rue Blaise Pascal, CS 90032, F-67081, 67081, Strasbourg, FRANCE
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8
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Sold S, Mummaneni BC, Michenfelder NC, Peng Y, Powell AK, Unterreiner AN, Lefkidis G, Hübner W. Experimental and Theoretical Study of the Ultrafast Dynamics of a Ni 2 Dy 2 -Compound in DMF After UV/Vis Photoexcitation. ChemistryOpen 2021; 11:e202100153. [PMID: 34931474 PMCID: PMC9059312 DOI: 10.1002/open.202100153] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Revised: 11/04/2021] [Indexed: 01/30/2023] Open
Abstract
We present a combined experimental and theoretical study of the ultrafast transient absorption spectroscopy results of a {Ni2Dy2}‐compound in DMF, which can be considered as a prototypic molecule for single molecule magnets. We apply state‐of‐the‐art ab initio quantum chemistry to quantitatively describe the optical properties of an inorganic complex system comprising ten atoms to form the chromophoric unit, which is further stabilized by surrounding ligands. Two different basis sets are used for the calculations to specifically identify two dominant peaks in the ground state. Furthermore, we theoretically propagate the compound's correlated many‐body wavefunction under the influence of a laser pulse as well as relaxation processes and compare against the time‐resolved absorption spectra. The experimental data can be described with a time constant of several hundreds of femtoseconds attributed to vibrational relaxation and trapping into states localized within the band gap. A second time constant is ascribed to the excited state while trap states show lifetimes on a longer timescale. The theoretical propagation is performed with the density‐matrix formalism and the Lindblad superoperator, which couples the system to a thermal bath, allowing us to extract relaxation times from first principles.
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Affiliation(s)
- S Sold
- Department of Physics and Research Center OPTIMAS, Technische Universität Kaiserslautern, P.O. Box 3049, 67653, Kaiserslautern, Germany
| | - B C Mummaneni
- Department of Physics and Research Center OPTIMAS, Technische Universität Kaiserslautern, P.O. Box 3049, 67653, Kaiserslautern, Germany
| | - N C Michenfelder
- Institute of Physical Chemistry, Karlsruhe Institute of Technology, Fritz-Haber-Weg 2, 76131, Karlsruhe, Germany
| | - Y Peng
- Institute of Inorganic Chemistry, Karlsruhe Institute of Technology, Engesserstrasse 15, 76131, Karlsruhe, Germany.,Institute of Nanotechnology, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344, Eggenstein-Leopoldshafen, Germany
| | - A K Powell
- Institute of Inorganic Chemistry, Karlsruhe Institute of Technology, Engesserstrasse 15, 76131, Karlsruhe, Germany.,Institute of Nanotechnology, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344, Eggenstein-Leopoldshafen, Germany
| | - A-N Unterreiner
- Institute of Physical Chemistry, Karlsruhe Institute of Technology, Fritz-Haber-Weg 2, 76131, Karlsruhe, Germany
| | - G Lefkidis
- Department of Physics and Research Center OPTIMAS, Technische Universität Kaiserslautern, P.O. Box 3049, 67653, Kaiserslautern, Germany.,School of Mechanics, Civil Engineering and Architecture, Northwestern Polytechnical University, Xi'an, 710072, China
| | - W Hübner
- Department of Physics and Research Center OPTIMAS, Technische Universität Kaiserslautern, P.O. Box 3049, 67653, Kaiserslautern, Germany
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Georgiev M, Chamati H. An Exchange Mechanism for the Magnetic Behavior of Er 3+ Complexes. Molecules 2021; 26:molecules26164922. [PMID: 34443510 PMCID: PMC8400239 DOI: 10.3390/molecules26164922] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 08/03/2021] [Accepted: 08/03/2021] [Indexed: 11/16/2022] Open
Abstract
We study the magnetic properties of the erbium based compounds, Na9[Er(W5O18)2] and [(Pc)Er{Pc{N(C4H9)2}8}]·/-, in the framework of an effective spin exchange model involving delocalized electrons occupying molecular orbitals. The calculations successfully reproduce the experimental data available in the literature for the magnetic spectrum, magnetization and molar susceptibility in dc and ac fields. Owing to their similar molecular geometry, the compounds' magnetic behaviors are interpreted in terms of the same set of active orbitals and thus the same effective spin coupling scheme. For all three complexes, the model predicts a prompt change in the ground state from a Kramer's doublet at zero fields to a fully polarized quartet one brought about by the action of an external magnetic field without Zeeman splitting. This alteration is attributed to the enhancement of the effect of orbital interactions over the spin exchange as the magnitude of the external magnetic field increases.
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10
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Konstantinidis NP. Discontinuous quantum and classical magnetic response of the pentakis dodecahedron. J Phys Condens Matter 2021; 33:325801. [PMID: 34184639 DOI: 10.1088/1361-648x/ac0477] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Accepted: 05/24/2021] [Indexed: 06/13/2023]
Abstract
The pentakis dodecahedron, the dual of the truncated icosahedron, consists of 60 edge-sharing triangles. It has 20 six-fold and 12 five-fold coordinated vertices, with the former forming a dodecahedron, and each of the latter connected to the vertices of one of the 12 pentagons of the dodecahedron. When spins mounted on the vertices of the pentakis dodecahedron interact according to the nearest-neighbor antiferromagnetic Heisenberg model, the two different vertex types necessitate the introduction of two exchange constants. As the relative strength of the two constants is varied the molecule interpolates between the dodecahedron and a molecule consisting only of quadrangles. The competition between the two exchange constants, frustration, and an external magnetic field results in a multitude of ground-state magnetization and susceptibility discontinuities. At the classical level the maximum is ten magnetization and one susceptibility discontinuities when the 12 five-fold vertices interact with the dodecahedron spins with approximately one-half the strength of their interaction. When the two interactions are approximately equal in strength the number of discontinuities is also maximized, with three of the magnetization and eight of the susceptibility. At the full quantum limit, where the magnitude of the spins equals12, there can be up to three ground-state magnetization jumps that have thez-component of the total spin changing by ΔSz= 2, even though quantum fluctuations rarely allow discontinuities of the magnetization. The full quantum case also supports a ΔSz= 3 discontinuity. Frustration also results in nonmagnetic states inside the singlet-triplet gap. These results make the pentakis dodecahedron the molecule with the largest number of magnetization and susceptibility discontinuities from the quantum to the classical level, taking its size also into account.
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Affiliation(s)
- N P Konstantinidis
- Department of Mathematics and Natural Sciences, The American University of Iraq, Sulaimani, Kirkuk Main Road, Sulaymaniyah, Kurdistan Region, Iraq
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11
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Sas W, Pinkowicz D, Perzanowski M, Fitta M. Magnetic, Structural and Spectroscopic Properties of Iron(II)-Octacyanoniobate(IV) Crystalline Film Obtained by Ion-Exchange Synthesis. Materials (Basel) 2020; 13:ma13133029. [PMID: 32645872 PMCID: PMC7372376 DOI: 10.3390/ma13133029] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Revised: 07/01/2020] [Accepted: 07/02/2020] [Indexed: 11/24/2022]
Abstract
Over recent years, investigations of coordination polymer thin films have been initiated due to their unique properties, which are expected to be strongly enhanced in the thin film form. In this work, a crystalline [FeII(H2O)2]2[NbIV(CN)8]∙4H2O (1) film on a transparent Nafion membrane was obtained, for the first time, via ion-exchange synthesis. The proper film formation and its composition was confirmed with the use of energy dispersive X-ray spectroscopy and infrared spectroscopy, as well as in situ Ultraviolet-Visible (UV-Vis) spectroscopy. The obtained film were also characterized by scanning electron microscopy, X-ray diffraction, and magnetic measurements. The [FeII(H2O)2]2[NbIV(CN)8]∙4H2O film shows a sharp phase transition to a long-range magnetically ordered state at Tc = 40 K. The 1 film is a soft ferromagnet with the coercive field Hc = 1.2 kOe. Compared to the bulk counterpart, a decrease in critical temperature and a significant increase in the coercive field were observed in the films indicating a distinct size effect. The decrease in Tc could also have been related to the possible partial oxidation of FeII ions to FeIII, which could be efficient, due to the large surface of the thin film sample.
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Affiliation(s)
- Wojciech Sas
- Institute of Nuclear Physics Polish Academy of Sciences, Radzikowskiego 152, 31-342 Krakow, Poland; (W.S.); (M.P.)
| | - Dawid Pinkowicz
- Faculty of Chemistry, Jagiellonian University, Gronostajowa 2, 30-387 Kraków, Poland;
| | - Marcin Perzanowski
- Institute of Nuclear Physics Polish Academy of Sciences, Radzikowskiego 152, 31-342 Krakow, Poland; (W.S.); (M.P.)
| | - Magdalena Fitta
- Institute of Nuclear Physics Polish Academy of Sciences, Radzikowskiego 152, 31-342 Krakow, Poland; (W.S.); (M.P.)
- Correspondence:
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12
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Zhang J, Deng Y, Hu X, Chi X, Liu J, Chu W, Sun L. Molecular Magnets Based on Graphenes and Carbon Nanotubes. Adv Mater 2019; 31:e1804917. [PMID: 30462864 DOI: 10.1002/adma.201804917] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2018] [Revised: 08/22/2018] [Indexed: 06/09/2023]
Abstract
Molecular magnets are demonstrated to provide a promising way to realize nanometer-scale structures with a stable spin orientation. Herein, first a description of conventional molecular magnets coupled with sp2 carbon materials, such as carbon nanotubes and graphenes, is given. Then, progress on ferromagnetism in sp2 carbon nanomaterials due to the existence of defects or topological structures as the spin units, which makes the sp2 materials themselves act as a novel class of molecular magnets, is reviewed, and a scheme of controllable synthesis of the molecular magnets at the sheared ends of carbon nanotubes is proposed. To conclude, remarks on some challenges and perspectives in the synthesis of carbon nanotube arrays with orderly sheared ends as integrated molecular magnets are provided.
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Affiliation(s)
- Jian Zhang
- CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, University of Chinese Academy of Sciences, Beijing, 100190, China
| | - Ya Deng
- CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, University of Chinese Academy of Sciences, Beijing, 100190, China
| | - Xiao Hu
- CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, University of Chinese Academy of Sciences, Beijing, 100190, China
| | - Xiannian Chi
- CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, University of Chinese Academy of Sciences, Beijing, 100190, China
| | - Jia Liu
- CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, University of Chinese Academy of Sciences, Beijing, 100190, China
| | - Weiguo Chu
- CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, University of Chinese Academy of Sciences, Beijing, 100190, China
| | - Lianfeng Sun
- CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, University of Chinese Academy of Sciences, Beijing, 100190, China
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13
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Magott M, Stefańczyk O, Sieklucka B, Pinkowicz D. Octacyanidotungstate(IV) Coordination Chains Demonstrate a Light-Induced Excited Spin State Trapping Behavior and Magnetic Exchange Photoswitching. Angew Chem Int Ed Engl 2017; 56:13283-13287. [PMID: 28770580 DOI: 10.1002/anie.201703934] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2017] [Revised: 07/09/2017] [Indexed: 11/07/2022]
Abstract
A huge increase in the magnetization of two coordination chains based on tetravalent octacyanidometalates (WIV and MoIV ) is observed on irradiation with 436 nm light, while no such behavior is observed for the NbIV analogue. A photomagnetic response based solely on [WIV (CN)8 ]4- is demonstrated for the first time. The observed behavior is attributed to the light-induced excited spin state trapping (LIESST) effect at the octacyanidometalate, and to the resulting magnetic exchange ON/OFF photoswitching between the MnII center and the photoinduced high-spin (S=1) WIV or MoIV centers.
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Affiliation(s)
- Michał Magott
- Faculty of Chemistry, Jagiellonian University, Gronostajowa 2, 30-387 Kraków, Poland
| | - Olaf Stefańczyk
- Department of Chemistry, School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Barbara Sieklucka
- Faculty of Chemistry, Jagiellonian University, Gronostajowa 2, 30-387 Kraków, Poland
| | - Dawid Pinkowicz
- Faculty of Chemistry, Jagiellonian University, Gronostajowa 2, 30-387 Kraków, Poland
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14
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McInnes EJL, Timco GA, Whitehead GFS, Winpenny REP. Heterometallic Rings: Their Physics and use as Supramolecular Building Blocks. Angew Chem Int Ed Engl 2015; 54:14244-69. [PMID: 26459810 DOI: 10.1002/anie.201502730] [Citation(s) in RCA: 95] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2015] [Indexed: 11/10/2022]
Abstract
An enormous family of heterometallic rings has been made. The first were Cr7 M rings where M = Ni(II), Zn(II), Mn(II), and rings have been made with as many as fourteen metal centers in the cyclic structure. They are bridged externally by carboxylates, and internally by fluorides or a penta-deprotonated polyol. The size of the rings is controlled through templates which have included a range of ammonium or imidazolium ions, alkali metals and coordination compounds. The rings can be functionalized to act as ligands, and incorporated into hybrid organic-inorganic rotaxanes and into molecules containing up to 200 metal centers. Physical studies reported include: magnetic measurements, inelastic neutron scattering (including single crystal measurements), electron paramagnetic resonance spectroscopy (including measurements of phase memory times), NMR spectroscopy (both solution and solid state), and polarized neutron diffraction. The rings are hence ideal for understanding magnetism in elegant exchange-coupled systems.
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Affiliation(s)
- Eric J L McInnes
- School of Chemistry and Photon Science Institute, The University of Manchester, Oxford Road, Manchester M13 9PL (UK)
| | - Grigore A Timco
- School of Chemistry and Photon Science Institute, The University of Manchester, Oxford Road, Manchester M13 9PL (UK)
| | - George F S Whitehead
- School of Chemistry and Photon Science Institute, The University of Manchester, Oxford Road, Manchester M13 9PL (UK)
| | - Richard E P Winpenny
- School of Chemistry and Photon Science Institute, The University of Manchester, Oxford Road, Manchester M13 9PL (UK).
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15
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Shen H. The synthesis, crystal structure and magnetic properties of a one-dimensional terbium(III)-octacyanidomolybdate(V) assembly. Acta Crystallogr C Struct Chem 2014; 70:1169-73. [PMID: 25471419 DOI: 10.1107/s2053229614024085] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2014] [Accepted: 10/31/2014] [Indexed: 11/10/2022]
Abstract
A one-dimensional cyanide-bridged coordination polymer, poly[[aquadi-μ-cyanido-κ(4)C:N-hexacyanido-κ(6)C-(dimethylformamide-κO)bis(3,4,7,8-tetramethyl-1,10-phenanthroline-κ(2)N,N')terbium(III)molybdate(V)] 4.5-hydrate], [MoTb(CN)8(C16H16N2)2(C3H7NO)(H2O)]·4.5H2O}n, has been prepared and characterized through IR spectroscopy, elemental analysis and single-crystal X-ray diffraction. The compound consists of one-dimensional chains in which cationic [Tb(tmphen)2(DMF)(H2O)](3+) (tmphen is 3,4,7,8-tetramethyl-1,10-phenanthroline) and anionic [Mo(V)(CN)8](3-) units are linked in an alternating fashion through bridging cyanide ligands. Neighbouring chains are connected by three types of hydrogen bonds (O-H···O, O-H···N and C-H···O) and by π-π interactions to form a three-dimensional supramolecular structure. In addition, magnetic investigations show that ferromagnetic interactions exist in the compound.
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Affiliation(s)
- Hong Shen
- City Vocational College of Jiangsu, Jiangsu Open University, Nanjing 210036, People's Republic of China
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16
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Bhatt P, Banerjee S, Anwar S, Mukadam MD, Meena SS, Yusuf SM. Core-shell Prussian blue analogue molecular magnet Mn(1.5)[Cr(CN)6]·mH2O@Ni(1.5)[Cr(CN)6]·nH2O for hydrogen storage. ACS Appl Mater Interfaces 2014; 6:17579-17588. [PMID: 25310858 DOI: 10.1021/am503526c] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Core-shell Prussian blue analogue molecular magnet Mn1.5[Cr(CN)6]·mH2O@Ni1.5[Cr(CN)6]·nH2O has been synthesized using a core of Mn1.5[Cr(CN)6]·7.5H2O, surrounded by a shell of Ni1.5[Cr(CN)6]·7.5H2O compound. A transmission electron microscopy (TEM) study confirms the core-shell nature of the nanoparticles with an average size of ∼25 nm. The core-shell nanoparticles are investigated by using x-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS) and elemental mapping, X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), and infrared (IR) spectroscopy. The Rietveld refinement of the XRD pattern reveals that the core-shell compound has a face-centered cubic crystal structure with space group Fm3m. The observation of characteristic absorption bands in the range of 2000-2300 cm(-1) in IR spectra corresponds to the CN stretching frequency of Mn(II)/Ni(II)-N≡C-Cr(III) sequence, confirming the formation of Prussian blue analogues. Hydrogen absorption isotherm measurements have been used to investigate the kinetics of molecular hydrogen adsorption into core-shell compounds of the Prussian blue analogue at low temperature conditions. Interestingly, the core-shell compound shows an enhancement in the hydrogen capacity (2.0 wt % at 123 K) as compared to bare-core and bare-shell compounds. The hydrogen adsorption capacity has been correlated with the specific surface area and TGA analysis of the core-shell compound. To the best of our knowledge, this is the first report on the hydrogen storage properties of core-shell Prussian blue analogue molecular magnet that could be useful for hydrogen storage applications.
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Affiliation(s)
- Pramod Bhatt
- Solid State Physics Division and ‡Chemistry Division, Bhabha Atomic Research Centre , Mumbai 400085, India
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17
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Packwood DM, Reaves KT, Federici FL, Katzgraber HG, Teizer W. Two-dimensional molecular magnets with weak topological invariant magnetic moments: mathematical prediction of targets for chemical synthesis. Proc Math Phys Eng Sci 2013; 469:20130373. [PMID: 24353469 DOI: 10.1098/rspa.2013.0373] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2013] [Accepted: 08/27/2013] [Indexed: 11/12/2022] Open
Abstract
An open problem in applied mathematics is to predict interesting molecules that are realistic targets for chemical synthesis. In this paper, we use a spin Hamiltonian-type model to predict molecular magnets (MMs) with magnetic moments that are intrinsically robust under random shape deformations to the molecule. Using the concept of convergence in probability, we show that for MMs in which all spin centres lie in-plane and all spin centre interactions are ferromagnetic, the total spin of the molecule is a 'weak topological invariant' when the number of spin centres is sufficiently large. By weak topological invariant, we mean that the total spin of the molecule depends only upon the arrangement of spin centres in the molecule, and is unlikely to change under shape deformations to the molecule. Our calculations show that only between 20 and 50 spin centres are necessary for the total spin of these MMs to be a weak topological invariant. The robustness effect is particularly enhanced for two-dimensional ferromagnetic MMs that possess a small number of spin rings in the structure.
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Affiliation(s)
- D M Packwood
- WPI-Advanced Institute for Materials Research , Tohoku University , 2-1-1, Katahira, Aoba-ku, Sendai 980-8577, Japan
| | - K T Reaves
- WPI-Advanced Institute for Materials Research , Tohoku University , 2-1-1, Katahira, Aoba-ku, Sendai 980-8577, Japan ; Materials Science and Engineering , Texas A&M University , College Station, TX 77843-3003, USA
| | - F L Federici
- WPI-Advanced Institute for Materials Research , Tohoku University , 2-1-1, Katahira, Aoba-ku, Sendai 980-8577, Japan ; Department of Physics and Astronomy , University College London , Gower Street, London WC1E 6BT, UK
| | - H G Katzgraber
- Materials Science and Engineering , Texas A&M University , College Station, TX 77843-3003, USA ; Department of Physics and Astronomy , Texas A&M University , College Station, TX 77843-4242, USA
| | - W Teizer
- WPI-Advanced Institute for Materials Research , Tohoku University , 2-1-1, Katahira, Aoba-ku, Sendai 980-8577, Japan ; Materials Science and Engineering , Texas A&M University , College Station, TX 77843-3003, USA ; Department of Physics and Astronomy , Texas A&M University , College Station, TX 77843-4242, USA
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18
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May F, Wegewijs MR, Hofstetter W. Interaction of spin and vibrations in transport through single-molecule magnets. Beilstein J Nanotechnol 2011; 2:693-8. [PMID: 22043459 PMCID: PMC3201623 DOI: 10.3762/bjnano.2.75] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/02/2011] [Accepted: 09/03/2011] [Indexed: 05/31/2023]
Abstract
We study electron transport through a single-molecule magnet (SMM) and the interplay of its anisotropic spin with quantized vibrational distortions of the molecule. Based on numerical renormalization group calculations we show that, despite the longitudinal anisotropy barrier and small transverse anisotropy, vibrational fluctuations can induce quantum spin-tunneling (QST) and a QST-Kondo effect. The interplay of spin scattering, QST and molecular vibrations can strongly enhance the Kondo effect and induce an anomalous magnetic field dependence of vibrational Kondo side-bands.
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Affiliation(s)
- Falk May
- Institut für Theoretische Physik, Johann Wolfgang Goethe-Universität, 60438 Frankfurt/Main, Germany
- Max Planck Institute for Polymer Research, 55128 Mainz, Germany
| | - Maarten R Wegewijs
- Institut für Theorie der Statistischen Physik, RWTH Aachen, 52056 Aachen, Germany
- Peter Grünberg Institut and JARA - Fundamentals of Information Technology, Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Walter Hofstetter
- Institut für Theoretische Physik, Johann Wolfgang Goethe-Universität, 60438 Frankfurt/Main, Germany
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19
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Urdampilleta M, Nguyen NV, Cleuziou JP, Klyatskaya S, Ruben M, Wernsdorfer W. Molecular quantum spintronics: supramolecular spin valves based on single-molecule magnets and carbon nanotubes. Int J Mol Sci 2011; 12:6656-67. [PMID: 22072910 PMCID: PMC3211001 DOI: 10.3390/ijms12106656] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2011] [Revised: 09/14/2011] [Accepted: 09/26/2011] [Indexed: 11/16/2022] Open
Abstract
We built new hybrid devices consisting of chemical vapor deposition (CVD) grown carbon nanotube (CNT) transistors, decorated with TbPc(2) (Pc = phthalocyanine) rare-earth based single-molecule magnets (SMMs). The drafting was achieved by tailoring supramolecular π-π interactions between CNTs and SMMs. The magnetoresistance hysteresis loop measurements revealed steep steps, which we can relate to the magnetization reversal of individual SMMs. Indeed, we established that the electronic transport properties of these devices depend strongly on the relative magnetization orientations of the grafted SMMs. The SMMs are playing the role of localized spin polarizer and analyzer on the CNT electronic conducting channel. As a result, we measured magneto-resistance ratios up to several hundred percent. We used this spin valve effect to confirm the strong uniaxial anisotropy and the superparamagnetic blocking temperature (T(B) ~ 1 K) of isolated TbPc(2) SMMs. For the first time, the strength of exchange interaction between the different SMMs of the molecular spin valve geometry could be determined. Our results introduce a new design for operable molecular spintronic devices using the quantum effects of individual SMMs.
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Affiliation(s)
- Matias Urdampilleta
- Institut Néel, CNRS et Université Joseph Fourier, BP 166, F-38042 Grenoble Cedex 9, France; E-Mails: (M.U.); (N.-V.N.); (J.-P.C.)
| | - Ngoc-Viet Nguyen
- Institut Néel, CNRS et Université Joseph Fourier, BP 166, F-38042 Grenoble Cedex 9, France; E-Mails: (M.U.); (N.-V.N.); (J.-P.C.)
| | - Jean-Pierre Cleuziou
- Institut Néel, CNRS et Université Joseph Fourier, BP 166, F-38042 Grenoble Cedex 9, France; E-Mails: (M.U.); (N.-V.N.); (J.-P.C.)
| | - Svetlana Klyatskaya
- Institute of Nanotechnology (INT), Karlsruhe Institute of Technology (KIT), 76344 Eggenstein-Leopoldshafen, Germany; E-Mails: (S.K.); (M.R.)
| | - Mario Ruben
- Institute of Nanotechnology (INT), Karlsruhe Institute of Technology (KIT), 76344 Eggenstein-Leopoldshafen, Germany; E-Mails: (S.K.); (M.R.)
- Institute de Physique et Chimie de Matériaux de Strasbourg (IPCMS), CNRS-Université de Strasbourg, 67034 Strasbourg, France
| | - Wolfgang Wernsdorfer
- Institut Néel, CNRS et Université Joseph Fourier, BP 166, F-38042 Grenoble Cedex 9, France; E-Mails: (M.U.); (N.-V.N.); (J.-P.C.)
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +33-0-47688-7909
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