Robust magnetic anisotropy of a monolayer of hexacoordinate Fe(<scp>ii</scp>) complexes assembled on Cu(111)

Kelaï, Massine; Cahier, Benjamin; Atanasov, Mihail; Neese, Frank; Tong, Yongfeng; Zhang, Luqiong; Bellec, Amandine; Iasco, Olga; Rivière, Éric; Guillot, Régis; Girard, Yann; Rousset, Sylvie; Repain, Vincent; Otero, Edwige; Arrio, Marie‐Anne; Sainctavit, Philippe; Barra, Anne‐Laure; Boillot, Marie‐Laure; Mallah, Talal

doi:10.1039/d1qi00085c

Cited by 9 publications

(8 citation statements)

References 33 publications

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“…A thorough STM analysis confirmed the integrity as well as the self-assembly of (1) on Cu(111). 20,41 The prepared sample is transferred in a homemade vacuum suitcase with pressure in the low 10 −10 mbar and transported within few hours to the X-ray absorption spectroscopy (XAS) measurement on beamline DEIMOS, Synchrotron SOLEIL. For all the samples, the XAS is performed with circularly polarized X-ray with an energy resolution better than 150 meV.…”

Section: Methodsmentioning

confidence: 99%

Thermal Bistability of an Ultrathin Film of Iron(II) Spin-Crossover Molecules Directly Adsorbed on a Metal Surface

Kelaï

Repain

Tauzin

et al. 2021

J. Phys. Chem. Lett.

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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 spincrossover compound Fe II ((3,5-(CH 3 ) 2 Pz) 3 BH) 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 depend 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. In order 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. Graphical TOC EntryFor thin films down to three-monolayer thick, spin-crossover molecules present an thermal hysteresis when adsorbed on Cu(111).

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Section: Methodsmentioning

confidence: 99%

Thermal Bistability of an Ultrathin Film of Iron(II) Spin-Crossover Molecules Directly Adsorbed on a Metal Surface

Kelaï

Repain

Tauzin

et al. 2021

J. Phys. Chem. Lett.

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“…The two-dimensional molecular layers grown on metallic substrates are composed of [Fe II ((3,5-(CH 3 ) 2 Pz) 3 BH) 2 ] (Pz = pyrazolyl) spin-crossover molecules, called FeMPz in the following, which exhibit a hysteretic thermal transition between a diamagnetic low spin (LS) state and a paramagnetic high spin (HS) state at a temperature around 190 K in bulk . On both Au(111) , and Cu(111) , substrates, the molecules FeMPz self-assembled in a molecular 2D network (see Figure S1 and the Supporting Information). At low temperature, as evidenced by XAS experiments, the molecules coexist in both high spin and low spin states that are imaged by STM at 0.3 V as dark and bright molecules, respectively .…”

mentioning

confidence: 99%

Voltage-Induced Bistability of Single Spin-Crossover Molecules in a Two-Dimensional Monolayer

Tong

Kelaï

Repain

et al. 2021

J. Phys. Chem. Lett.

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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 selfassembled 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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“…In fact, before the present study the SCO transition in the tetragonal "metastable" polymorph was considered to be inactive and all the previous studies were focused on the triclinic "stable" polymorph. [9,23,[28][29][30][43][44][45][46][47] That was mainly due to the high sensitivity of the tetragonal polymorph to light irradiation, alongside its very low spin transition temperature and its intrinsic structural instability above room temperature (undergoing a conversion toward the triclinic polymorph). Here, this elusive polymorph has been properly isolated demonstrating a fast light-induced spin switching with more robustness and efficiency when integrated in the in-contact devices as compared with the triclinicbased ones (50% compared to 15%, after irradiating for 5 and 60 min, respectively).…”

Section: Discussionmentioning

confidence: 99%

Electrical Sensing of the Thermal and Light‐Induced Spin Transition in Robust Contactless Spin‐Crossover/Graphene Hybrid Devices

et al. 2022

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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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Robust magnetic anisotropy of a monolayer of hexacoordinate Fe(ii) complexes assembled on Cu(111)

Abstract: The measurement of the magnetic anisotropy of [Fe{(3,5-(CH3)2Pz)3BH}2], where Pz = pyrazole, in its high spin S =2 state by X-ray Magnetic Circular Dichroism (XMCD) spectroscopy when assembled as an...

Cited by 9 publications

References 33 publications

Thermal Bistability of an Ultrathin Film of Iron(II) Spin-Crossover Molecules Directly Adsorbed on a Metal Surface

Thermal Bistability of an Ultrathin Film of Iron(II) Spin-Crossover Molecules Directly Adsorbed on a Metal Surface

Voltage-Induced Bistability of Single Spin-Crossover Molecules in a Two-Dimensional Monolayer

Electrical Sensing of the Thermal and Light‐Induced Spin Transition in Robust Contactless Spin‐Crossover/Graphene Hybrid Devices

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