1
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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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2
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Luo YH, Jin XT, Zhang SX, Xue C, Liu M. Dynamic Aggregation Triggering Reversible Spin-State Switching. ACS APPLIED MATERIALS & INTERFACES 2023; 15:48365-48374. [PMID: 37793189 DOI: 10.1021/acsami.3c10181] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/06/2023]
Abstract
The manipulation of spin-state switching (SSS) under ambient conditions is of significant importance for the construction of molecular switches. Herein, we demonstrate that reversible SSS can be mediated by the aggregation state of a near-infrared (NIR)-sensitive ferrous complex. The ferrous complex was J-aggregated in a DMF suspension and with a low-spin (LS) state; however, with the addition of water, it changed to H-aggregation and reached a high-spin (HS) state, owing to the enhanced intramolecular charge transfer and metal-to-ligand charge transfer. Interestingly, the following NIR irradiation can restore the J-aggregation and LS states owing to the enhanced ligand-to-ligand charge transfer. More interestingly, the ferrous complex can be further incorporated into a hygroscopic sponge that was capable of capturing humidity effectively for all weather conditions, which displayed reversible SSS via alternating atmospheric humidity capture and NIR irradiation under ambient conditions in the sponge state. This study thus opens up a new avenue for the development of novel smart molecular switches at the device level.
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Affiliation(s)
- Yang-Hui Luo
- School of Chemistry and Chemical Engineering, Southeast University, Nanjing 211189, P. R. China
| | - Xue-Ting Jin
- School of Chemistry and Chemical Engineering, Southeast University, Nanjing 211189, P. R. China
| | - Shu-Xin Zhang
- School of Chemistry and Chemical Engineering, Southeast University, Nanjing 211189, P. R. China
| | - Cheng Xue
- School of Chemistry and Chemical Engineering, Southeast University, Nanjing 211189, P. R. China
| | - Min Liu
- School of Chemistry and Chemical Engineering, Southeast University, Nanjing 211189, P. R. China
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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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Salhi J, Calupitan JP, Mattera M, Montero D, Miche A, Maruchenko R, Proust A, Izzet G, Kreher D, Arfaoui I, Volatron F. Ready-to-be-addressed oxo-clusters: individualized, periodically organized and separated from the substrate. NANOSCALE 2023; 15:13233-13238. [PMID: 37540202 DOI: 10.1039/d3nr02649c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/05/2023]
Abstract
Clusters and oxo-clusters are drawing attention for their amazing physical properties, especially at the scale of the single molecule. However, chemical methods to organize them individually on a surface are still lacking. In this study we show that it is possible to periodically organize individual polyoxometalates thanks to their ordering by a new supramolecular assembly.
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Affiliation(s)
- Juba Salhi
- Institut parisien de chimie moléculaire (IPCM), CNRS, Sorbonne Université, 4 Place Jussieu, F-75005 Paris, France.
| | - Jan Patrick Calupitan
- Institut parisien de chimie moléculaire (IPCM), CNRS, Sorbonne Université, 4 Place Jussieu, F-75005 Paris, France.
| | - Michele Mattera
- Institut parisien de chimie moléculaire (IPCM), CNRS, Sorbonne Université, 4 Place Jussieu, F-75005 Paris, France.
| | - David Montero
- Fédération de chimie et matériaux de Paris-centre (FCMat), Sorbonne Université, 4 Place Jussieu, F-75005 Paris, France
| | - Antoine Miche
- Laboratoire de réactivité de surface (LRS), CNRS, Sorbonne Université, 4 Place Jussieu, F-75005 Paris, France
| | - Régina Maruchenko
- Institut parisien de chimie moléculaire (IPCM), CNRS, Sorbonne Université, 4 Place Jussieu, F-75005 Paris, France.
| | - Anna Proust
- Institut parisien de chimie moléculaire (IPCM), CNRS, Sorbonne Université, 4 Place Jussieu, F-75005 Paris, France.
| | - Guillaume Izzet
- Institut parisien de chimie moléculaire (IPCM), CNRS, Sorbonne Université, 4 Place Jussieu, F-75005 Paris, France.
| | - David Kreher
- Institut Lavoisier de Versailles (ILV), CNRS, Université Paris-Saclay, 45 avenue des Etats-Unis, F-78035 Versailles, France
| | - Imad Arfaoui
- De la molécule aux nano-objets: réactivité, interactions et spectroscopies (MONARIS), CNRS, Sorbonne Université, 4 Place Jussieu, F-75005 Paris, France
| | - Florence Volatron
- Institut parisien de chimie moléculaire (IPCM), CNRS, Sorbonne Université, 4 Place Jussieu, F-75005 Paris, France.
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5
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Grunwald J, Torres J, Buchholz A, Näther C, Kämmerer L, Gruber M, Rohlf S, Thakur S, Wende H, Plass W, Kuch W, Tuczek F. Defying the inverse energy gap law: a vacuum-evaporable Fe(ii) low-spin complex with a long-lived LIESST state. Chem Sci 2023; 14:7361-7380. [PMID: 37416721 PMCID: PMC10321519 DOI: 10.1039/d3sc00561e] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Accepted: 05/25/2023] [Indexed: 07/08/2023] Open
Abstract
The novel vacuum-evaporable complex [Fe(pypypyr)2] (pypypyr = bipyridyl pyrrolide) was synthesised and analysed as bulk material and as a thin film. In both cases, the compound is in its low-spin state up to temperatures of at least 510 K. Thus, it is conventionally considered a pure low-spin compound. According to the inverse energy gap law, the half time of the light-induced excited high-spin state of such compounds at temperatures approaching 0 K is expected to be in the regime of micro- or nanoseconds. In contrast to these expectations, the light-induced high-spin state of the title compound has a half time of several hours. We attribute this behaviour to a large structural difference between the two spin states along with four distinct distortion coordinates associated with the spin transition. This leads to a breakdown of single-mode behaviour and thus drastically decreases the relaxation rate of the metastable high-spin state. These unprecedented properties open up new strategies for the development of compounds showing light-induced excited spin state trapping (LIESST) at high temperatures, potentially around room temperature, which is relevant for applications in molecular spintronics, sensors, displays and the like.
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Affiliation(s)
- Jan Grunwald
- Institut für Anorganische Chemie, Christian-Albrechts-Universität zu Kiel 24098 Kiel Germany +49 431 880 1520 +49 431 880 1410
| | - Jorge Torres
- Institut für Experimentalphysik, Freie Universität Berlin Arnimallee 14 14195 Berlin Germany +49 30 838 452098 +49 30 838 52098
| | - Axel Buchholz
- Institut für Anorganische und Analytische Chemie, Friedrich-Schiller-Universität Jena 07743 Jena Germany
| | - Christian Näther
- Institut für Anorganische Chemie, Christian-Albrechts-Universität zu Kiel 24098 Kiel Germany +49 431 880 1520 +49 431 880 1410
| | - Lea Kämmerer
- Fakultät für Physik and CENIDE, Universität Duisburg-Essen 47048 Duisburg Germany
| | - Manuel Gruber
- Fakultät für Physik and CENIDE, Universität Duisburg-Essen 47048 Duisburg Germany
| | - Sebastian Rohlf
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel 24098 Kiel Germany
| | - Sangeeta Thakur
- Institut für Experimentalphysik, Freie Universität Berlin Arnimallee 14 14195 Berlin Germany +49 30 838 452098 +49 30 838 52098
| | - Heiko Wende
- Fakultät für Physik and CENIDE, Universität Duisburg-Essen 47048 Duisburg Germany
| | - Winfried Plass
- Institut für Anorganische und Analytische Chemie, Friedrich-Schiller-Universität Jena 07743 Jena Germany
| | - Wolfgang Kuch
- Institut für Experimentalphysik, Freie Universität Berlin Arnimallee 14 14195 Berlin Germany +49 30 838 452098 +49 30 838 52098
| | - Felix Tuczek
- Institut für Anorganische Chemie, Christian-Albrechts-Universität zu Kiel 24098 Kiel Germany +49 431 880 1520 +49 431 880 1410
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6
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Chen H, Yang HH, Frauhammer T, You H, Sun Q, Nagel P, Schuppler S, Gaspar AB, Real JA, Wulfhekel W. Observation of Exchange Interaction in Iron(II) Spin Crossover Molecules in Contact with Passivated Ferromagnetic Surface of Co/Au(111). SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2023; 19:e2300251. [PMID: 36828799 DOI: 10.1002/smll.202300251] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Indexed: 06/02/2023]
Abstract
Spin crossover (SCO) complexes sensitively react on changes of the environment by a change in the spin of the central metallic ion making them ideal candidates for molecular spintronics. In particular, the composite of SCO complexes and ferromagnetic (FM) surfaces would allow spin-state switching of the molecules in combination with the magnetic exchange interaction to the magnetic substrate. Unfortunately, when depositing SCO complexes on ferromagnetic surfaces, spin-state switching is blocked by the relatively strong interaction between the adsorbed molecules and the surface. Here, the Fe(II) SCO complex [FeII (Pyrz)2 ] (Pyrz = 3,5-dimethylpyrazolylborate) with sub-monolayer thickness in contact with a passivated FM film of Co on Au(111) is studied. In this case, the molecules preserve thermal spin crossover and at the same time the high-spin species show a sizable exchange interaction of > 0.9 T with the FM Co substrate. These observations provide a feasible design strategy in fabricating SCO-FM hybrid devices.
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Affiliation(s)
- Hongyan Chen
- Physikalisches Institut, Karlsruhe Institute of Technology (KIT), 76131, Karlsruhe, Germany
| | - Hung-Hsiang Yang
- Physikalisches Institut, Karlsruhe Institute of Technology (KIT), 76131, Karlsruhe, Germany
| | - Timo Frauhammer
- Physikalisches Institut, Karlsruhe Institute of Technology (KIT), 76131, Karlsruhe, Germany
| | - Haoran You
- Physikalisches Institut, Karlsruhe Institute of Technology (KIT), 76131, Karlsruhe, Germany
| | - Qing Sun
- Laboratory for Electron Microscopy, Karlsruhe Institute of Technology (KIT), 76131, Karlsruhe, Germany
| | - Peter Nagel
- Electron Spectroscopy Group, Institute for Quantum Materials and Technologies (IQMT), Karlsruhe Institute of Technology (KIT), 76021, Karlsruhe, Germany
- Karlsruhe Nano Micro Facility (KNMFi), Karlsruhe Institute of Technology (KIT), 76344, Eggenstein-Leopoldshafen, Germany
| | - Stefan Schuppler
- Electron Spectroscopy Group, Institute for Quantum Materials and Technologies (IQMT), Karlsruhe Institute of Technology (KIT), 76021, Karlsruhe, Germany
- Karlsruhe Nano Micro Facility (KNMFi), Karlsruhe Institute of Technology (KIT), 76344, Eggenstein-Leopoldshafen, Germany
| | - Ana Belén Gaspar
- Institut de Ciència Molecular (ICMol), Universitat de València, C/Catedrático José Beltrán Martínez 2, 46980, Paterna, Valencia, Spain
| | - José Antonio Real
- Institut de Ciència Molecular (ICMol), Universitat de València, C/Catedrático José Beltrán Martínez 2, 46980, Paterna, Valencia, Spain
| | - Wulf Wulfhekel
- Physikalisches Institut, Karlsruhe Institute of Technology (KIT), 76131, Karlsruhe, Germany
- Quantum Control Group, Institute for Quantum Materials and Technologies (IQMT), Karlsruhe Institute of Technology (KIT), 76021, Karlsruhe, Germany
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7
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Yazdani S, Phillips J, Ekanayaka TK, Cheng R, Dowben PA. The Influence of the Substrate on the Functionality of Spin Crossover Molecular Materials. Molecules 2023; 28:molecules28093735. [PMID: 37175145 PMCID: PMC10180229 DOI: 10.3390/molecules28093735] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2023] [Revised: 04/18/2023] [Accepted: 04/18/2023] [Indexed: 05/15/2023] Open
Abstract
Spin crossover complexes are a route toward designing molecular devices with a facile readout due to the change in conductance that accompanies the change in spin state. Because substrate effects are important for any molecular device, there are increased efforts to characterize the influence of the substrate on the spin state transition. Several classes of spin crossover molecules deposited on different types of surface, including metallic and non-metallic substrates, are comprehensively reviewed here. While some non-metallic substrates like graphite seem to be promising from experimental measurements, theoretical and experimental studies indicate that 2D semiconductor surfaces will have minimum interaction with spin crossover molecules. Most metallic substrates, such as Au and Cu, tend to suppress changes in spin state and affect the spin state switching process due to the interaction at the molecule-substrate interface that lock spin crossover molecules in a particular spin state or mixed spin state. Of course, the influence of the substrate on a spin crossover thin film depends on the molecular film thickness and perhaps the method used to deposit the molecular film.
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Affiliation(s)
- Saeed Yazdani
- Department of Physics, Indiana University-Purdue University Indianapolis, Indianapolis, IN 46202, USA
| | - Jared Phillips
- Department of Physics, Indiana University-Purdue University Indianapolis, Indianapolis, IN 46202, USA
| | - Thilini K Ekanayaka
- Department of Physics and Astronomy, Jorgensen Hall, University of Nebraska, Lincoln, NE 68588-0299, USA
| | - Ruihua Cheng
- Department of Physics, Indiana University-Purdue University Indianapolis, Indianapolis, IN 46202, USA
| | - Peter A Dowben
- Department of Physics and Astronomy, Jorgensen Hall, University of Nebraska, Lincoln, NE 68588-0299, USA
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8
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Kelai M, Tauzin A, Railean A, Repain V, Lagoute J, Girard Y, Rousset S, Otero E, Mallah T, Boillot ML, Enachescu C, Bellec A. Interface versus Bulk Light-Induced Switching in Spin-Crossover Molecular Ultrathin Films Adsorbed on a Metallic Surface. J Phys Chem Lett 2023; 14:1949-1954. [PMID: 36787373 DOI: 10.1021/acs.jpclett.2c03733] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Spin-crossover molecules present the unique property of having two spin states that can be controlled by light excitation at low temperature. Here, we report on the photoexcitation of [FeII((3, 5-(CH3)2Pz)3BH)2] (Pz = pyrazolyl) ultrathin films, with thicknesses ranging from 0.9 to 5.3 monolayers, adsorbed on Cu(111) substrate. Using X-ray absorption spectroscopy measurements, we confirm the anomalous light-induced spin-state switching observed for sub-monolayer coverage and demonstrate that it is confined to the first molecular layer in contact with the metallic substrate. For higher coverages, the well-known light-induced excited spin-state trapping effect is recovered. Combining continuous light excitation with thermal cycling, we demonstrate that at low temperature light-induced thermal hysteresis is measured for the thicker films, while for sub-monolayer coverage, the light enables extension of the thermal conversion over a large temperature range. Mechanoelastic simulations underline that, due to the intermolecular interactions, opposite behaviors are observed in the different layers composing the films.
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Affiliation(s)
- Massine Kelai
- Université Paris Cité, CNRS, Laboratoire Matériaux et Phénomènes Quantiques, F-75013 Paris, France
| | - Arthur Tauzin
- Université Paris-Saclay, Institut de Chimie Moléculaire et des Matériaux d'Orsay, CNRS, UMR 8182, 91400 Orsay, France
| | - Anastasia Railean
- Faculty of Physics, Alexandru Ioan Cuza University of Iasi, Iasi 700506, Romania
| | - Vincent Repain
- Université Paris Cité, CNRS, Laboratoire Matériaux et Phénomènes Quantiques, F-75013 Paris, France
| | - Jérôme Lagoute
- Université Paris Cité, CNRS, Laboratoire Matériaux et Phénomènes Quantiques, F-75013 Paris, France
| | - Yann Girard
- Université Paris Cité, CNRS, Laboratoire Matériaux et Phénomènes Quantiques, F-75013 Paris, France
| | - Sylvie Rousset
- Université Paris Cité, CNRS, Laboratoire Matériaux et Phénomènes Quantiques, F-75013 Paris, France
| | - Edwige Otero
- Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin, 91192 Gif sur Yvette, France
| | - Talal Mallah
- Université Paris-Saclay, Institut de Chimie Moléculaire et des Matériaux d'Orsay, CNRS, UMR 8182, 91400 Orsay, France
| | - Marie-Laure Boillot
- Université Paris-Saclay, Institut de Chimie Moléculaire et des Matériaux d'Orsay, CNRS, UMR 8182, 91400 Orsay, France
| | - Cristian Enachescu
- Faculty of Physics, Alexandru Ioan Cuza University of Iasi, Iasi 700506, Romania
| | - Amandine Bellec
- Université Paris Cité, CNRS, Laboratoire Matériaux et Phénomènes Quantiques, F-75013 Paris, France
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9
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Resines-Urien E, Fernandez-Bartolome E, Martinez-Martinez A, Gamonal A, Piñeiro-López L, Costa JS. Vapochromic effect in switchable molecular-based spin crossover compounds. Chem Soc Rev 2023; 52:705-727. [PMID: 36484276 DOI: 10.1039/d2cs00790h] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Coordination complexes based on transition metal ions displaying [Ar]3d4-3d7 electronic configurations can undergo the likely most spectacular switchable phenomena found in molecular coordination chemistry, the well-known Spin Crossover (SCO). SCO phenomena is a detectable, reproducible and reversible switch that occurs between the high spin (HS) and low spin (LS) electronic states of the transition metal actuated by different stimuli (i.e. light, temperature, pressure, the presence of an analyte). Moreover, the occurrence of SCO phenomena causes different outputs, one of them being a colour change. Altogether, an analyte in gas form could be detected by naked eye once it has triggered the corresponding HS ↔ LS transition. This vapochromic effect could be used to detect volatile molecules using a low-cost technology, including harmful chemical substances, gases and/or volatile organic compounds (VOCs) that are present in our environment, in our home or at our workplace. The present review condenses all reported iron coordination compounds where the colour change induced by a given molecule in its gas form is coupled to a HS ↔ LS spin transition. Special emphasis has been made on describing the nature of the post-synthetic modification (PSM) taking place in the material upon the analyte uptake. In this case, three types of PSM can be distinguished: based on supramolecular contacts and/or leading to a coordinative or covalent bond. In the latter, a colour change not only indicates the switch of the spin state in the material but also the formation of a new compound with different properties. It is important to indicate that some of the SCO coordination compounds discussed in the current report have been part of other spin crossover reviews, that have gathered thermally induced SCO compounds and the influence of guest molecules on the SCO behaviour. However, in the majority of examples in these reviews, the change of colour upon the uptake of analytes is not associated with a spin transition at room temperature. In addition, the observed colour variations have been mainly discussed in terms of host-guest interactions, when they can also be induced by a PSM taking place in different sites of the molecule, like the Fe(II) coordination sphere or by chemically altering its inorganic and/or organic linkers. Therefore, we present here for the first time an exhaustive compilation of all systems in which the interaction between the coordination compounds and the vapour analytes leads to a colour change due to a spin transition in the metal centre at room temperature.
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10
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Gavara-Edo M, Córdoba R, Valverde-Muñoz FJ, Herrero-Martín J, Real JA, Coronado E. Electrical Sensing of the Thermal and Light-Induced Spin Transition in Robust Contactless Spin-Crossover/Graphene Hybrid Devices. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022; 34:e2202551. [PMID: 35766419 DOI: 10.1002/adma.202202551] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2022] [Revised: 05/26/2022] [Indexed: 06/15/2023]
Abstract
Hybrid devices based on spin-crossover (SCO)/2D heterostructures grant a highly sensitive platform to detect the spin transition in the molecular SCO component and tune the properties of the 2D material. However, the fragility of the SCO materials upon thermal treatment, light irradiation, or contact with surfaces and the methodologies used for their processing have limited their applicability. Here, an easily processable and robust SCO/2D hybrid device with outstanding performance based on the sublimable SCO [Fe(Pyrz)2 ] molecule deposited over chemical vapor deposition (CVD) graphene is reported, which is fully compatible with electronics industry protocols. Thus, a novel methodology based on growing an elusive polymorph of [Fe(Pyrz)2 ] (tetragonal phase) over graphene is developed that allows a fast and effective light-induced spin transition in the devices (≈50% yield in 5 min) to be detected electrically. Such performance can be enhanced even more when a flexible polymeric layer of poly(methyl methacrylate) is inserted in between the two active components in a contactless configuration, reaching a ≈100% yield in 5 min.
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Affiliation(s)
- Miguel Gavara-Edo
- Institute of Molecular Science, University of Valencia, Catedrático José Beltrán 2, Paterna, 46980, Spain
| | - Rosa Córdoba
- Institute of Molecular Science, University of Valencia, Catedrático José Beltrán 2, Paterna, 46980, Spain
| | | | | | - José Antonio Real
- Institute of Molecular Science, University of Valencia, Catedrático José Beltrán 2, Paterna, 46980, Spain
| | - Eugenio Coronado
- Institute of Molecular Science, University of Valencia, Catedrático José Beltrán 2, Paterna, 46980, Spain
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11
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Johannsen S, Ossinger S, Grunwald J, Herman A, Wende H, Tuczek F, Gruber M, Berndt R. Spin Crossover in a Cobalt Complex on Ag(111). Angew Chem Int Ed Engl 2022; 61:e202115892. [PMID: 35032345 PMCID: PMC9303790 DOI: 10.1002/anie.202115892] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Indexed: 12/05/2022]
Abstract
The Co‐based complex [Co(H2B(pz)(pypz))2] (py=pyridine, pz=pyrazole) deposited on Ag(111) was investigated with scanning tunneling microscopy at ≈5 K. Due to a bis(tridentate) coordination sphere the molecules aggregate mainly into tetramers. Individual complexes in these tetramers undergo reversible transitions between two states with characteristic image contrasts when current is passed through them or one of their neighbors. Two molecules exhibit this bistability while the other two molecules are stable. The transition rates vary linearly with the tunneling current and exhibit an intriguing dependence on the bias voltage and its polarity. We interpret the states as being due to S=1/2 and 3/2 spin states of the Co2+ complex. The image contrast and the orders‐of‐magnitude variations of the switching yields can be tentatively understood from the calculated orbital structures of the two spin states, thus providing first insights into the mechanism of electron‐induced excited spin‐state trapping (ELIESST).
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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.,Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056, Basel, Switzerland
| | - Jan Grunwald
- Institut für Anorganische Chemie, Christian-Albrechts-Universität, 24098, Kiel, Germany
| | - Alexander Herman
- Faculty of Physics and CENIDE, University of Duisburg-Essen, 47057, Duisburg, Germany
| | - Heiko Wende
- Faculty of Physics and CENIDE, University of Duisburg-Essen, 47057, Duisburg, Germany
| | - 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 and CENIDE, 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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12
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Johannsen S, Ossinger S, Grunwald J, Herman A, Wende H, Tuczek F, Gruber M, Berndt R. Spin Crossover in a Cobalt Complex on Ag(111). Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202115892] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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
- Department of Chemistry University of Basel St. Johanns-Ring 19 4056 Basel Switzerland
| | - Jan Grunwald
- Institut für Anorganische Chemie Christian-Albrechts-Universität 24098 Kiel Germany
| | - Alexander Herman
- Faculty of Physics and CENIDE University of Duisburg-Essen 47057 Duisburg Germany
| | - Heiko Wende
- Faculty of Physics and CENIDE University of Duisburg-Essen 47057 Duisburg Germany
| | - 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 and CENIDE 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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13
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Investigation of a Tetrathiafulvalene-Based Fe2+ Thermal Spin Crossover Assembled on Gold Surface. MAGNETOCHEMISTRY 2022. [DOI: 10.3390/magnetochemistry8020014] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
A thick film and a monolayer of tetrathiafulvalene-based Fe2+ spin-crossover complex have been deposited by solution on a Au (111) substrate, attempting both self-assembling monolayer protocol and a simpler drop-casting procedure. The thermally induced spin transition has been investigated using X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (XAS). Temperature-dependent investigations demonstrated the retention of the switching behavior between the two spin states in thick molecular films obtained by drop-casting, while in the monolayer sample, the loss of the spin-crossover properties appears as a possible consequence of the strong interaction between the sulfur atoms of the ligand and the gold substrate.
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14
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Sánchez-de-Armas R, Calzado CJ. Spin-crossover Fe(ii) complexes on a surface: a mixture of low-spin and high-spin molecules at low temperature from quantum-chemistry calculations. Inorg Chem Front 2022. [DOI: 10.1039/d1qi01487k] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The deposition of a 2D monolayer of an Fe(ii) SCO complex on Au(111) is studied by quantum chemistry calculations. The results indicate that there exists thermodynamic and kinetic factors favoring the presence of the mixed HS/LS state at low temperature.
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Affiliation(s)
- Rocío Sánchez-de-Armas
- Departamento de Química Física, Universidad de Sevilla, calle Prof. García González, s/n, 41012 Sevilla, Spain
| | - Carmen J. Calzado
- Departamento de Química Física, Universidad de Sevilla, calle Prof. García González, s/n, 41012 Sevilla, Spain
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15
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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: 25] [Impact Index Per Article: 8.3] [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.
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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
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16
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Tong Y, Kelaï M, Bairagi K, Repain V, Lagoute J, Girard Y, Rousset S, Boillot ML, Mallah T, Enachescu C, Bellec A. Voltage-Induced Bistability of Single Spin-Crossover Molecules in a Two-Dimensional Monolayer. J Phys Chem Lett 2021; 12:11029-11034. [PMID: 34743521 DOI: 10.1021/acs.jpclett.1c03271] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Bistable spin-crossover molecules are particularly interesting for the development of innovative electronic and spintronic devices as they present two spin states that can be controlled by external stimuli. In this paper, we report the voltage-induced switching of the high spin/low spin electronic states of spin-crossover molecules self-assembled in dense 2D networks on Au(111) and Cu(111) by scanning tunneling microscopy at low temperature. On Au(111), voltage pulses lead to the nonlocal switching of the molecules from any─high or low─spin state to the other followed by a spontaneous relaxation toward their initial state within minutes. On the other hand, on Cu(111), single molecules can be addressed at will. They retain their new electronic configuration after a voltage pulse. The memory effect demonstrated on Cu(111) is due to an interplay between long-range intermolecular interaction and molecule/substrate coupling as confirmed by mechanoelastic simulations.
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Affiliation(s)
- Yongfeng Tong
- Université de Paris, Laboratoire Matériaux et Phénomènes Quantiques (MPQ), CNRS-UMR7162, 75013, Paris, France
| | - Massine Kelaï
- Université de Paris, Laboratoire Matériaux et Phénomènes Quantiques (MPQ), CNRS-UMR7162, 75013, Paris, France
| | - Kaushik Bairagi
- Université de Paris, Laboratoire Matériaux et Phénomènes Quantiques (MPQ), CNRS-UMR7162, 75013, Paris, France
| | - Vincent Repain
- Université de Paris, Laboratoire Matériaux et Phénomènes Quantiques (MPQ), CNRS-UMR7162, 75013, Paris, France
| | - Jérôme Lagoute
- Université de Paris, Laboratoire Matériaux et Phénomènes Quantiques (MPQ), CNRS-UMR7162, 75013, Paris, France
| | - Yann Girard
- Université de Paris, Laboratoire Matériaux et Phénomènes Quantiques (MPQ), CNRS-UMR7162, 75013, Paris, France
| | - Sylvie Rousset
- Université de Paris, Laboratoire Matériaux et Phénomènes Quantiques (MPQ), CNRS-UMR7162, 75013, Paris, France
| | - Marie-Laure Boillot
- Institut de Chimie Moléculaire et des Matériaux d'Orsay, Université Paris-Saclay, CNRS, UMR 8182, 91405 Orsay Cedex, France
| | - Talal Mallah
- Institut de Chimie Moléculaire et des Matériaux d'Orsay, Université Paris-Saclay, CNRS, UMR 8182, 91405 Orsay Cedex, France
| | - Cristian Enachescu
- Faculty of Physics, Alexandru Ioan Cuza University of Iasi, Iasi 700506, Romania
| | - Amandine Bellec
- Université de Paris, Laboratoire Matériaux et Phénomènes Quantiques (MPQ), CNRS-UMR7162, 75013, Paris, France
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17
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Cao T, Valverde-Muñoz FJ, Duan X, Zhang M, Wang P, Xing L, Sun F, Zhou Z, Liu H, Jiang J, Muñoz MC, Real JA, Zhang D. Spin Crossover in a Series of Non-Hofmann-Type Fe(II) Coordination Polymers Based on [Hg(SeCN) 3] - or [Hg(SeCN) 4] 2- Building Blocks. Inorg Chem 2021; 60:11048-11057. [PMID: 34279097 DOI: 10.1021/acs.inorgchem.1c00802] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Self-assembly of [Hg(SeCN)4]2- tetrahedral building blocks, iron(II) ions, and a series of bis-monodentate pyridyl-type bridging ligands has afforded the new heterobimetallic HgII-FeII coordination polymers {Fe[Hg(SeCN)3]2(4,4'-bipy)2}n (1), {Fe[Hg(SeCN)4](tvp)}n (2), {Fe[Hg(SeCN)3]2(4,4'-azpy)2}n (3), {Fe[Hg(SeCN)4](4,4'-azpy)(MeOH)}n (4), {Fe[Hg(SeCN)4](3,3'-bipy)}n (5) and {Fe[Hg(SeCN)4](3,3'-azpy)}n (6) (4,4-bipy = 4,4'-bipyridine, tvp = trans-1,2-bis(4-pyridyl)ethylene, 4,4'-azpy = 4,4'-azobispyridine, 3,3-bipy = 3,3'-bipyridine, 3,3'-azpy = 3,3'-azobispyridine). Single-crystal X-ray analyses show that compounds 1 and 3 display a two-dimensional robust sheet structure made up of infinite linear [(FeL)n]2n+ (L = 4,4'-bipy or 4,4'-azpy) chains linked by in situ formed {[Hg(L)(SeCN)3]2}2- anionic dimeric bridges. Complexes 2 and 4-6 define three-dimensional networks with different topological structures, indicating, in combination with complexes 1 and 3, that the polarity, length, rigidity, and conformation of the bridging organic ligand play important roles in the structural nature of the products reported here. The magnetic properties of complexes 1 and 2 show the occurrence of temperature- and light-induced spin crossover (SCO) properties, while complexes 4-6 are in the high-spin state at all temperatures. The current results provide a new route for the design and synthesis of new SCO functional materials with non-Hofmann-type traditional structures.
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Affiliation(s)
- Tong Cao
- College of Chemical and Chemical Engineering, Shandong University of Technology, Zibo 255049, People's Republic of China
| | - Francisco Javier Valverde-Muñoz
- Instituto de Ciencia Molecular (ICMol), Universitat de València, C/Catedrático José Beltrán Martínez 2, 46980 Paterna (Valencia), Spain
| | - Xiaoyi Duan
- College of Chemical and Chemical Engineering, Shandong University of Technology, Zibo 255049, People's Republic of China
| | - Mingjian Zhang
- College of Chemical and Chemical Engineering, Shandong University of Technology, Zibo 255049, People's Republic of China
| | - Ping Wang
- College of Chemical and Chemical Engineering, Shandong University of Technology, Zibo 255049, People's Republic of China
| | - Lingbao Xing
- College of Chemical and Chemical Engineering, Shandong University of Technology, Zibo 255049, People's Republic of China
| | - Fenggang Sun
- College of Chemical and Chemical Engineering, Shandong University of Technology, Zibo 255049, People's Republic of China
| | - Zhen Zhou
- College of Chemical and Chemical Engineering, Shandong University of Technology, Zibo 255049, People's Republic of China
| | - Hui Liu
- College of Chemical and Chemical Engineering, Shandong University of Technology, Zibo 255049, People's Republic of China
| | - Jianzhuang Jiang
- Department of Chemistry, University of Science and Technology Beijing, Beijing 100083, People's Republic of China
| | - M Carmen Muñoz
- Departamento de Física Aplicada, Universitat Politècnica de València, Camino de Vera s/n, E-46022 Valencia, Spain
| | - José Antonio Real
- Instituto de Ciencia Molecular (ICMol), Universitat de València, C/Catedrático José Beltrán Martínez 2, 46980 Paterna (Valencia), Spain
| | - Daopeng Zhang
- College of Chemical and Chemical Engineering, Shandong University of Technology, Zibo 255049, People's Republic of China
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18
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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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19
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Kelai M, Repain V, Tauzin A, Li W, Girard Y, Lagoute J, Rousset S, Otero E, Sainctavit P, Arrio MA, Boillot ML, Mallah T, Enachescu C, Bellec A. Thermal Bistability of an Ultrathin Film of Iron(II) Spin-Crossover Molecules Directly Adsorbed on a Metal Surface. J Phys Chem Lett 2021; 12:6152-6158. [PMID: 34184899 DOI: 10.1021/acs.jpclett.1c01366] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Spin-crossover molecules are very attractive compounds to realize multifunctional spintronic devices. Understanding their properties when deposited on metals is therefore crucial for their future rational implementation as ultrathin films in such devices. Using X-ray absorption spectroscopy, we study the thermal transition of the spin-crossover compound FeII((3,5-(CH3)2Pz)3BH)2 from submonolayer to multilayers on a Cu(111) substrate. We determine how the residual fraction of high spin molecules at low temperature, as well as the bistability range and the temperature of switching, depends on the layer thickness. The most spectacular effect is the clear opening of a 35 ± 9 K thermal hysteresis loop for a 3.0 ± 0.7 monolayers thick film. To better understand the role played by the substrate and the dimensionality on the thermal bistability, we have performed Monte Carlo Arrhenius simulations in the framework of a mechanoelastic model that include a molecule-substrate interaction. This model reproduces well the main features observed experimentally and can predict how the spin-crossover transition is modified by the thickness and the substrate interaction.
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Affiliation(s)
- Massine Kelai
- Matériaux et Phénomènes Quantiques, Université de Paris, CNRS UMR 7162, 75013 Paris, France
| | - Vincent Repain
- Matériaux et Phénomènes Quantiques, Université de Paris, CNRS UMR 7162, 75013 Paris, France
| | - Arthur Tauzin
- Institut de Chimie Moléculaire et des Matériaux d'Orsay, Univ Paris Sud, Université Paris-Saclay, CNRS, UMR 8182, 91405 Orsay Cedex, France
| | - Weibin Li
- Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, CNRS UMR7590, Sorbonne Université, MNHN, 75252 Paris Cedex 5, France
| | - Yann Girard
- Matériaux et Phénomènes Quantiques, Université de Paris, CNRS UMR 7162, 75013 Paris, France
| | - Jérôme Lagoute
- Matériaux et Phénomènes Quantiques, Université de Paris, CNRS UMR 7162, 75013 Paris, France
| | - Sylvie Rousset
- Matériaux et Phénomènes Quantiques, Université de Paris, CNRS UMR 7162, 75013 Paris, France
| | - Edwige Otero
- Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin, 91192 Gif sur Yvette, France
| | - Philippe Sainctavit
- Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, CNRS UMR7590, Sorbonne Université, MNHN, 75252 Paris Cedex 5, France
- Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin, 91192 Gif sur Yvette, France
| | - Marie-Anne Arrio
- Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, CNRS UMR7590, Sorbonne Université, MNHN, 75252 Paris Cedex 5, France
| | - Marie-Laure Boillot
- Institut de Chimie Moléculaire et des Matériaux d'Orsay, Univ Paris Sud, Université Paris-Saclay, CNRS, UMR 8182, 91405 Orsay Cedex, France
| | - Talal Mallah
- Institut de Chimie Moléculaire et des Matériaux d'Orsay, Univ Paris Sud, Université Paris-Saclay, CNRS, UMR 8182, 91405 Orsay Cedex, France
| | - Cristian Enachescu
- Faculty of Physics, Alexandru Ioan Cuza University of Iasi, Iasi, 700506, Romania
| | - Amandine Bellec
- Matériaux et Phénomènes Quantiques, Université de Paris, CNRS UMR 7162, 75013 Paris, France
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Kipgen L, Bernien M, Tuczek F, Kuch W. Spin-Crossover Molecules on Surfaces: From Isolated Molecules to Ultrathin Films. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2021; 33:e2008141. [PMID: 33963619 DOI: 10.1002/adma.202008141] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Revised: 01/22/2021] [Indexed: 06/12/2023]
Abstract
Molecular spintronics seeks to use single or few molecules as functional building blocks for spintronic applications, directly relying on molecular properties or properties of interfaces between molecules and inorganic electrodes. Spin-crossover molecules (SCMs) are one of the most promising classes of candidates for molecular spintronics due to their bistability deriving from the existence of two spin states that can be reversibly switched by temperature, light, electric fields, etc. Building devices based on single or few molecules would entail connecting the molecule(s) with solid surfaces and understanding the fundamental behavior of the resulting assemblies. Herein, the investigations of SCMs on solid surfaces, ranging from isolated single molecules (submonolayers) to ultrathin films (mainly in the sub-10 nm range) are summarized. The achievements, challenges and prospects in this field are highlighted.
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Affiliation(s)
- Lalminthang Kipgen
- Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, 14195, Berlin, Germany
| | - Matthias Bernien
- Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, 14195, Berlin, Germany
| | - Felix Tuczek
- Institut für Anorganische Chemie, Christian-Albrechts-Universität zu Kiel, Max-Eyth-Straße 2, 24118, Kiel, Germany
| | - Wolfgang Kuch
- Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, 14195, Berlin, Germany
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21
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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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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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