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Kamel SM, Daróczi L, Tóth LZ, Beke DL, Juárez GG, Cobo S, Salmon L, Molnár G, Bousseksou A. Acoustic emissions from spin crossover complexes. JOURNAL OF MATERIALS CHEMISTRY. C 2024; 12:5757-5765. [PMID: 38680543 PMCID: PMC11044199 DOI: 10.1039/d4tc00495g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/05/2024] [Accepted: 03/19/2024] [Indexed: 05/01/2024]
Abstract
Acoustic emission from the compounds [Fe(HB(tz)3)2] and [Fe(Htrz)(trz)2]BF4 was detected during the thermally induced spin transition and is correlated with simultaneously recorded calorimetric signals. We ascribe this phenomenon to elastic waves produced by microstructural and volume changes accompanying the spin transition. Despite the perfect reversibility of the spin state switching (seen by the calorimeter), the acoustic emission activity decreases for successive thermal cycles, revealing thus irreversible microstructural evolution of the samples. The acoustic emission signal amplitude and energy probability distribution functions followed power-law behavior and the characteristic exponents were found to be similar for the two samples both on heating and cooling, indicating the universal character, which is further substantiated by the well scaled average temporal shapes of the avalanches.
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Affiliation(s)
- Sarah M Kamel
- Department of Solid State Physics, Doctoral School of Physics, University of Debrecen P.O. Box 2 H-4010 Debrecen Hungary
- Physics Department, Faculty of Science Ain Shams University, Abbassia 11566 Cairo Egypt
| | - Lajos Daróczi
- Department of Solid State Physics, Doctoral School of Physics, University of Debrecen P.O. Box 2 H-4010 Debrecen Hungary
| | - László Z Tóth
- Department of Solid State Physics, Doctoral School of Physics, University of Debrecen P.O. Box 2 H-4010 Debrecen Hungary
| | - Dezső L Beke
- Department of Solid State Physics, Doctoral School of Physics, University of Debrecen P.O. Box 2 H-4010 Debrecen Hungary
| | - Gerardo Gutiérrez Juárez
- Departamento de Ingeniería Física, División de Ciencias e Ingenierías, Universidad de Guanajuato-Campus León, Loma del Bosque 103, Loma del Campestre 37150 León Gto. Mexico
| | - Saioa Cobo
- LCC, CNRS & University of Toulouse, 205 route de Narbonne 31077 Toulouse France
| | - Lionel Salmon
- LCC, CNRS & University of Toulouse, 205 route de Narbonne 31077 Toulouse France
| | - Gábor Molnár
- LCC, CNRS & University of Toulouse, 205 route de Narbonne 31077 Toulouse France
| | - Azzedine Bousseksou
- LCC, CNRS & University of Toulouse, 205 route de Narbonne 31077 Toulouse France
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2
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Torres-Cavanillas R, Gavara-Edo M, Coronado E. Bistable Spin-Crossover Nanoparticles for Molecular Electronics. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024; 36:e2307718. [PMID: 37725707 DOI: 10.1002/adma.202307718] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2023] [Revised: 08/25/2023] [Indexed: 09/21/2023]
Abstract
The field of spin-crossover complexes is rapidly evolving from the study of the spin transition phenomenon to its exploitation in molecular electronics. Such spin transition is gradual in a single-molecule, while in bulk it can be abrupt, showing sometimes thermal hysteresis and thus a memory effect. A convenient way to keep this bistability while reducing the size of the spin-crossover material is to process it as nanoparticles (NPs). Here, the most recent advances in the chemical design of these NPs and their integration into electronic devices, paying particular attention to optimizing the switching ratio are reviewed. Then, integrating spin-crossover NPs over 2D materials is focused to improve the endurance, performance, and detection of the spin state in these hybrid devices.
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Affiliation(s)
- Ramón Torres-Cavanillas
- Instituto de Ciencia Molecular, Universitat de València, Valencia, 46980, Spain
- Department of Materials, Oxford University, Oxford, OX2 6NN, UK
| | - Miguel Gavara-Edo
- Instituto de Ciencia Molecular, Universitat de València, Valencia, 46980, Spain
| | - Eugenio Coronado
- Instituto de Ciencia Molecular, Universitat de València, Valencia, 46980, Spain
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3
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Johannsen S, Gruber M, Barreteau C, Seredyuk M, Antonio Real J, Markussen T, Berndt R. Spin-Crossover and Fragmentation of Fe(neoim) 2 on Silver and Gold. J Phys Chem Lett 2023; 14:7814-7823. [PMID: 37623823 DOI: 10.1021/acs.jpclett.3c01551] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/26/2023]
Abstract
The neutral spin crossover complex Fe(neoim)2, neoim being the deprotonated form of the ionogenic ligand 2-(1H-imidazol-2-yl)-9-methyl-1,10-phenanthroline (neoimH), is investigated on the (111) surfaces of Au and Ag using scanning tunneling microscopy and density functional theory calculations. The complex sublimates and adsorbs intact on Ag(111), where it exhibits an electron-induced spin crossover. However, it fragments on Au. According to density functional theory calculations, the adsorbed complex is drastically distorted by the interactions with the substrates, in particular by van der Waals forces. Dispersion interaction is also decisive for the relative stabilities of the low- and high-spin states of the adsorbed complex. The unexpected instability of the complex on the gold substrate is attributed to enhanced covalent bonding of the fragments to the substrate.
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Affiliation(s)
- Sven Johannsen
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität, 24098 Kiel, Germany
| | - Manuel Gruber
- Faculty of Physics and CENIDE, University of Duisburg-Essen, 47057 Duisburg, Germany
| | - Cyrille Barreteau
- Université Paris-Saclay CEA, CNRS SPEC, 91191 Gif-sur-Yvette, France
| | - Maksym Seredyuk
- Instituto de Ciencia Molecular (ICMol)/Departamento de Química Inorgánica, Universidad de Valencia, 46980 Paterna, Valencia, Spain
- Department of Chemistry, Taras Shevchenko National University of Kyiv, 64/13 Volodymyrska Street 01601 Kyiv, Ukraine
| | - José Antonio Real
- Instituto de Ciencia Molecular (ICMol)/Departamento de Química Inorgánica, Universidad de Valencia, 46980 Paterna, Valencia, Spain
| | | | - Richard Berndt
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität, 24098 Kiel, Germany
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4
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Molecular memory near room temperature in an iron polyanionic complex. Chem 2022. [DOI: 10.1016/j.chempr.2022.09.025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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5
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Li D, Tong Y, Bairagi K, Kelai M, Dappe YJ, Lagoute J, Girard Y, Rousset S, Repain V, Barreteau C, Brandbyge M, Smogunov A, Bellec A. Negative Differential Resistance in Spin-Crossover Molecular Devices. J Phys Chem Lett 2022; 13:7514-7520. [PMID: 35944010 DOI: 10.1021/acs.jpclett.2c01934] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
We demonstrate, based on low-temperature scanning tunneling microscopy (STM) and spectroscopy, a pronounced negative differential resistance (NDR) in spin-crossover (SCO) molecular devices, where a FeII SCO molecule is deposited on surfaces. The STM measurements reveal that the NDR is robust with respect to substrate materials, temperature, and the number of SCO layers. This indicates that the NDR is intrinsically related to the electronic structure of the SCO molecule. Experimental results are supported by density functional theory (DFT) with nonequilibrium Green's function (NEGF) calculations and a generic theoretical model. While the DFT+NEGF calculations reproduce NDR for a special atomically sharp STM tip, the effect is attributed to the energy-dependent tip density of states rather than the molecule itself. We, therefore, propose a Coulomb blockade model involving three molecular orbitals with very different spatial localization as suggested by the molecular electronic structure.
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Affiliation(s)
- Dongzhe Li
- Department of Physics, Technical University of Denmark, DK-2800 Kongens Lyngby, Denmark
- CEMES, Université de Toulouse, CNRS, 29 rue Jeanne Marvig, F-31055 Toulouse, France
| | - Yongfeng Tong
- Université Paris Cité, CNRS, Laboratoire Matériaux et Phénomènes Quantiques UMR7162, 75013 Paris, France
| | - Kaushik Bairagi
- Université Paris Cité, CNRS, Laboratoire Matériaux et Phénomènes Quantiques UMR7162, 75013 Paris, France
| | - Massine Kelai
- Université Paris Cité, CNRS, Laboratoire Matériaux et Phénomènes Quantiques UMR7162, 75013 Paris, France
| | - Yannick J Dappe
- Université Paris-Saclay, CEA, CNRS, SPEC, 91191 Gif-sur-Yvette, France
| | - Jérôme Lagoute
- Université Paris Cité, CNRS, Laboratoire Matériaux et Phénomènes Quantiques UMR7162, 75013 Paris, France
| | - Yann Girard
- Université Paris Cité, CNRS, Laboratoire Matériaux et Phénomènes Quantiques UMR7162, 75013 Paris, France
| | - Sylvie Rousset
- Université Paris Cité, CNRS, Laboratoire Matériaux et Phénomènes Quantiques UMR7162, 75013 Paris, France
| | - Vincent Repain
- Université Paris Cité, CNRS, Laboratoire Matériaux et Phénomènes Quantiques UMR7162, 75013 Paris, France
| | - Cyrille Barreteau
- Université Paris-Saclay, CEA, CNRS, SPEC, 91191 Gif-sur-Yvette, France
| | - Mads Brandbyge
- Department of Physics, Technical University of Denmark, DK-2800 Kongens Lyngby, Denmark
- Center for Nanostructured Graphene, Technical University of Denmark, DK-2800 Kongens Lyngby, Denmark
| | | | - Amandine Bellec
- Université Paris Cité, CNRS, Laboratoire Matériaux et Phénomènes Quantiques UMR7162, 75013 Paris, France
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Johannsen S, Ossinger S, Markussen T, Tuczek F, Gruber M, Berndt R. Electron-Induced Spin-Crossover in Self-Assembled Tetramers. ACS NANO 2021; 15:11770-11778. [PMID: 34133115 DOI: 10.1021/acsnano.1c02698] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The spin crossover compound Fe(H2B(pyrazole)(pyridylpyrazole))2 was investigated in detail on Ag(111) with scanning tunneling microscopy (STM). A large fraction of the deposited molecules condenses into gridlike tetramers. Two molecules of each tetramer may be converted between two states by current injection. We attribute this effect to a spin transition. This interpretation is supported by control experiments on the analogous, magnetically passive Zn compound that forms virtually identical tetramers but exhibits no switching. The switching yields were studied for various electron energies, and the resulting values exceed those reported from other SCO systems by 2 orders of magnitude. The other two molecules of a tetramer were immutable. However, they may be used as contacts for current injection that leads to conversion of one of their neighbors. This "remote" switching is fairly efficient with yields reduced by only one to two orders of magnitude compared to direct excitation of a switchable molecule. We present a model of the tetramer structure that reproduces key observations from the experiments. In particular, sterical blocking prevents spin crossover of two molecules of a tetramer. Density functional theory calculations show that the model indeed represents a minimum energy structure. They also reproduce STM images and corroborate a remote-switching mechanism that is based on electron transfer between molecules.
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Affiliation(s)
- Sven Johannsen
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität, 24098 Kiel, Germany
| | - Sascha Ossinger
- Institut für Anorganische Chemie, Christian-Albrechts-Universität, 24098 Kiel, Germany
| | - Troels Markussen
- Synopsys Denmark, Fruebjergvej 3, Postbox 4, DK-2100 Copenhagen, Denmark
| | - Felix Tuczek
- Institut für Anorganische Chemie, Christian-Albrechts-Universität, 24098 Kiel, Germany
| | - Manuel Gruber
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität, 24098 Kiel, Germany
- Faculty of Physics, University of Duisburg-Essen, 47057 Duisburg, Germany
| | - Richard Berndt
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität, 24098 Kiel, Germany
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Nonvolatile Voltage Controlled Molecular Spin-State Switching for Memory Applications. MAGNETOCHEMISTRY 2021. [DOI: 10.3390/magnetochemistry7030037] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Nonvolatile, molecular multiferroic devices have now been demonstrated, but it is worth giving some consideration to the issue of whether such devices could be a competitive alternative for solid-state nonvolatile memory. For the Fe (II) spin crossover complex [Fe{H2B(pz)2}2(bipy)], where pz = tris(pyrazol-1-yl)-borohydride and bipy = 2,2′-bipyridine, voltage-controlled isothermal changes in the electronic structure and spin state have been demonstrated and are accompanied by changes in conductance. Higher conductance is seen with [Fe{H2B(pz)2}2(bipy)] in the high spin state, while lower conductance occurs for the low spin state. Plausibly, there is the potential here for low-cost molecular solid-state memory because the essential molecular thin films are easily fabricated. However, successful device fabrication does not mean a device that has a practical value. Here, we discuss the progress and challenges yet facing the fabrication of molecular multiferroic devices, which could be considered competitive to silicon.
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Karuppannan SK, Martín-Rodríguez A, Ruiz E, Harding P, Harding DJ, Yu X, Tadich A, Cowie B, Qi D, Nijhuis CA. Room temperature conductance switching in a molecular iron(iii) spin crossover junction. Chem Sci 2020; 12:2381-2388. [PMID: 34164002 PMCID: PMC8179334 DOI: 10.1039/d0sc04555a] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Herein, we report the first room temperature switchable Fe(iii) molecular spin crossover (SCO) tunnel junction. The junction is constructed from [FeIII(qsal-I)2]NTf2 (qsal-I = 4-iodo-2-[(8-quinolylimino)methyl]phenolate) molecules self-assembled on graphene surfaces with conductance switching of one order of magnitude associated with the high and low spin states of the SCO complex. Normalized conductance analysis of the current–voltage characteristics as a function of temperature reveals that charge transport across the SCO molecule is dominated by coherent tunnelling. Temperature-dependent X-ray absorption spectroscopy and density functional theory confirm the SCO complex retains its SCO functionality on the surface implying that van der Waals molecule—electrode interfaces provide a good trade-off between junction stability while retaining SCO switching capability. These results provide new insights and may aid in the design of other types of molecular devices based on SCO compounds. Herein, we report the first room temperature switchable Fe(iii) molecular spin crossover (SCO) tunnel junction.![]()
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Affiliation(s)
- Senthil Kumar Karuppannan
- Department of Chemistry, National University of Singapore 3 Science Drive Singapore 117543 Singapore
| | - Alejandro Martín-Rodríguez
- Departament de Química Inorgànica, Institut de Recerca de Química Teòrica i Computacional, Universitat de Barcelona Diagonal 645 08028 Barcelona Spain
| | - Eliseo Ruiz
- Departament de Química Inorgànica, Institut de Recerca de Química Teòrica i Computacional, Universitat de Barcelona Diagonal 645 08028 Barcelona Spain
| | - Phimphaka Harding
- Functional Materials and Nanotechnology Center of Excellence, Walailak University Thasala Nakhon Si Thammarat 80160 Thailand
| | - David J Harding
- Functional Materials and Nanotechnology Center of Excellence, Walailak University Thasala Nakhon Si Thammarat 80160 Thailand
| | - Xiaojiang Yu
- Singapore Synchrotron Light Source, National University of Singapore 5 Research Link Singapore 117603 Singapore
| | - Anton Tadich
- Australian Synchrotron Clayton Victoria 3168 Australia
| | - Bruce Cowie
- School of Chemistry and Physics, Queensland University of Technology Brisbane Queensland 4001 Australia
| | - Dongchen Qi
- School of Chemistry and Physics, Queensland University of Technology Brisbane Queensland 4001 Australia
| | - Christian A Nijhuis
- Department of Chemistry, National University of Singapore 3 Science Drive Singapore 117543 Singapore .,Centre for Advanced 2D Materials & Graphene Research, National University of Singapore 6 Science Drive 2 Singapore 117546 Singapore
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9
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Abstract
The transfer of the inherent bistability of spin crossover compounds to surfaces has attracted considerable interest in recent years. The deposition of the complexes on surfaces allows investigating them individually and to further understand the microscopic mechanisms at play. Moreover, it offers the prospect of engineering switchable functional surfaces. We review recent progress in the field with a particular focus on the challenges and limits associated with the dominant experimental techniques used, namely near-edge X-ray absorption fine structure (NEXAFS) spectroscopy and scanning tunneling microscopy (STM). One of the main difficulties in NEXAFS-based experiments is to ascertain that the complexes are in direct contact with the surfaces. We show that molecular coverage determination based on the amplitude of the edge-jump of interest is challenging because the latter quantity depends on the substrate. Furthermore, NEXAFS averages the signals of a large number of molecules, which may be in different states. In particular, we highlight that the signal of fragmented molecules is difficult to distinguish from that of intact and functional ones. In contrast, STM allows investigating individual complexes, but the identification of the spin states is at best done indirectly. As quite some of the limits of the techniques are becoming apparent as the field is gaining maturity, their detailed descriptions will be useful for future investigations and for taking a fresh look at earlier reports.
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