Spin crossover materials evaporated under clean high vacuum and ultra-high vacuum conditions: from thin films to single molecules

Palamarciuc, Titaniau; Oberg, Jenny C.; Hallak, Fadi El; Hirjibehedin, Cyrus F.; Serri, Michele; Heutz, Sandrine; Létard, Jean‐François; Rosa, Patrick

doi:10.1039/c2jm15094h

Cited by 105 publications

(167 citation statements)

References 42 publications

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“…We showed previously that thin films made by sublimation do preserve molecular integrity, 12,14,19 a result confirmed independently by other authors. [2][3][4]9 Indeed temperature-dependent magnetic properties of vacuum evaporated thin film samples measured using a superconducting quantum interference device (SQUID) magnetometer a Department of Physics and Astronomy, University of Nebraska -Lincoln, Lincoln, indicate a thermal SCO transition in agreement with earlier reports.…”

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confidence: 74%

The spin state of a molecular adsorbate driven by the ferroelectric substrate polarization

et al. 2014

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The spin state of [Fe(H2B(pz)2)2(bipy)] thin films is mediated by changes in the electric field at the interface of organic ferroelectric polyvinylidene fluoride with trifluoroethylene (PVDF-TrFE). Signatures of the molecular crossover transition are evident in changes in the unoccupied states and the related shift from diamagnetic to paramagnetic characteristics. This may point the way to the molecular magneto-electric effect on devices.

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confidence: 74%

The spin state of a molecular adsorbate driven by the ferroelectric substrate polarization

et al. 2014

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“…The efficiency of the light-induced conversion is close to 100%, as compared to some 60-80% as determined by magnetic measurements. This is not surprising since, asin reflectometry measurements, 25 TEY is probing the topmost layers of the sample (typically 1-5 nm), 47 The evaluation of the magnetic response through XMCD spectra fully supports our assignment of HS and LS states. Compound 1 behaves as a paramagnet: the XMCD signal measured is weak at 300 K, increases until SCO occurs, then becomes very weak down to 10 K.…”

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confidence: 68%

“…[2][3] This phenomenon can be driven using a variety of external inputs, including temperature, 4-5 light, [6][7][8] pressure, 9 magnetic field, 10 mechanical stress 11 and charge flow. [12][13][14][15][16][17] Recently, there has been a surge of interest in the study of the conversion properties of nanostructured SCO materials, in the form of nanoparticles, [18][19][20][21][22] thick films, [23][24][25] and even isolated molecules either bridging nanogaps [13][14][15] or on surfaces. [16][17] Integration of switchable molecular materials in nanoscale devices requires the retention of their conversion properties once deposited on a solid substrate.…”

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confidence: 99%

Temperature- and Light-Induced Spin Crossover Observed by X-ray Spectroscopy on Isolated Fe(II) Complexes on Gold

Warner¹,

Oberg²,

Gill³

et al. 2013

J. Phys. Chem. Lett.

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Using X-ray absorption techniques, we show that temperature-and light-induced spin crossover properties are conserved for a sub-monolayer of the [Fe(H 2 B(pz) 2 ) 2 (2,2'-bipy)] complex evaporated onto a Au(111) surface. For a significant fraction of the molecules, we see changes in the absorption at the L 2,3 edges that are consistent with those observed in bulk and thick film references. Assignment of these changes to spin crossover is further supported by multiplet calculations to simulate the x-ray absorption spectra. As others have observed in experiments on monolayer coverages, we find that many molecules in our submonolayer system remain pinned in one of the two spin states. Our results clearly demonstrate that temperature-and light-induced spin-crossover is possible for isolated molecules on surfaces, but that interactions with the surface may play a key role in determining when this can occur. TOC X-ray absorption techniques evidenced that temperature-and light-induced spin crossover properties were conserved for a sub-monolayer of the [Fe(H 2 B(pz) 2 ) 2 (2,2'-bipy)] complex evaporated on a Gold surface KEYWORDS: spin crossover,·UHV evaporation,·submonolayer,·X-ray absorption,·iron complexes 3 Spin Crossover (SCO) complexes are promising building blocks for spintronic 1 Using variable temperature X-ray absorption spectra, we examined a submonolayer coverage evaporated in situ under UHV conditions on Au(111), before and after irradiation with visible laser light. We compare these results to those obtained from two other samples: 1) a 5 single crystal finely scratched on gold foil, which we use as a spectroscopic bulk reference; and 2) a 300 nm thick film sublimedex situ on copper foil, to check the preservation of structure and properties of the complex. Experimental spectra were then compared to the ones obtained using multiplet calculations. 37-39The variation of the L 2,3 edge spectra for the bulk sample over the range of the thermal spin crossover (100-300 K) is reported in Figure 1a(see also Figure S1 in Supplementary Information Spectra measured on the thick film prepared ex situ are similar to the bulk, and show comparable temperature dependence (Figure 1b and Figure S1). Nevertheless, the thick film spectrum is slightly differentfrom the bulk compound: shoulders on the high-energy side (at 300 K) or at the low-energy side (at 100 K) of the L 3 absorption peak, are likely associated with a small fraction of decomposition product, which maybe caused by air exposure of this sample prepared ex situ.The analysis of the temperature-dependent spectra as weighted sums of the bulk spectra at 300 K and 100 K, chosen as representative of the HS and LS state respectively, allows for the extraction of the temperature dependence of the HS fraction (Table S2). For the thick film, the shoulder signals were found to be temperature independent, and thus do not affect the switching behavior. We extracted this spurious contribution ( Figures S3 and S4) and subtracted it from all spectra before evaluating...

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“…An interesting perspective has been published by Palamarciuc et al by performing STM imaging on isolated molecules of the [Fe(H 2 B(pz) 2 ) 2 (bipy)] SCO complex obtained by evaporation on a Cu(111) surface [69]. They observed a series of isolated molecules with different orientations from which they deduced the possible adsorbate conformation of the molecule on the surface.…”

Section: Single Molecule Studiesmentioning

confidence: 94%

Charge Transport and Electrical Properties of Spin Crossover Materials: Towards Nanoelectronic and Spintronic Devices

et al. 2016

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Abstract:In this paper, we present a comprehensive review of research on electrical and charge transport properties of spin crossover complexes. This includes both the effect of spin-state switching on the dielectric permittivity and electrical conductivity of the material and vice versa the influence of an applied electrical field (or current) on the spin-state of the system. The survey covers different size scales from bulk materials and thin films to nanoparticles and single molecules and embraces the presentation of several device prototypes and hybrid materials as well.

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Spin crossover materials evaporated under clean high vacuum and ultra-high vacuum conditions: from thin films to single molecules

Cited by 105 publications

References 42 publications

The spin state of a molecular adsorbate driven by the ferroelectric substrate polarization

The spin state of a molecular adsorbate driven by the ferroelectric substrate polarization

Temperature- and Light-Induced Spin Crossover Observed by X-ray Spectroscopy on Isolated Fe(II) Complexes on Gold

Charge Transport and Electrical Properties of Spin Crossover Materials: Towards Nanoelectronic and Spintronic Devices

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