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...

Epitaxial silicene, which forms spontaneously on ZrB2(0001) thin films grown on Si(111) wafers, has a periodic stripe domain structure. By adsorbing additional Si atoms on this surface, we find that the domain boundaries vanish, and a single-domain silicene sheet can be prepared without altering its buckled honeycomb structure. The amount of Si required to induce this change suggests that the domain boundaries are made of a local distortion of the silicene honeycomb lattice. The realization of a single domain sheet with structural and electronic properties close to those of the original striped state demonstrates the high structural flexibility of silicene.

Using low energy electron diffraction (LEED) and scanning tunnelling microscopy (STM), we observe a new two-dimensional (2D) silicon crystal that is formed by depositing additional Si atoms onto spontaneously-formed epitaxial silicene on a ZrB 2 thin film. From scanning tunnelling spectroscopy (STS) studies, we find that this atomically-thin layered silicon has distinctly different electronic properties. Angle resolved photoelectron spectroscopy (ARPES) reveals that, in sharp contrast to epitaxial silicene, the layered silicon exhibits significantly enhanced density of states at the Fermi level resulting from newly formed metallic bands. The 2D growth of this material could allow for direct contacting to the silicene surface and demonstrates the dramatic changes in electronic structure that can occur by the addition of even a single monolayer amount of material in 2D systems. LETTER Original content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence.

occurs when 2D materials are placed on a substrate, such as when they are epitaxially grown upon a metallic surface. [11,12] For example, it has been shown that molecules can become trapped within nanopores of hexagonal boron nitride grown on Ru (0001) because of dipolar interactions; [13,14] similar results have also been observed for nanopores on the surface of bulk SiC. [15] Physisorption of a molecule to a surface (i.e., van der Waals bonding) is often not strong enough to fix the molecule's position at room temperature, particularly on the surface of bulk metal crystals. This is more readily accomplished by anchoring the mole cule to the surface through chemisorption of part of the molecule to the surface. [16][17][18] However, care must be taken to limit hybridization that can cause detrimental modifications of the molecule and its frontier orbitals, [19,20] especially on different surface reconstructions of bulk semiconductors like silicon. [15,17] It is therefore of interest to investigate the interface between molecules and more reactive 2D materials in an attempt to isolate individual molecules at room temperature while retaining their localized electronic states.With its mixed sp 2 -sp 3 character, silicene-the silicon analogue of graphene-has the potential to provide unique properties for molecular templating. This is particularly true because the structural and electronic properties of silicene are more susceptible to modification [21][22][23][24][25][26] once it is formed upon a surface, owing to its greater reactivity than graphene and the flexibility of The interactions between atomic or molecular adsorbates and the surfaces of 2D materials are of interest for applications ranging from catalysis [1] and molecular sensing [2] to molecular electronics and spintronics. [3][4][5] For the prototypical 2D material graphene, there are typically only weak van der Waals interactions between molecules and the surface. [6] This allows for the fabrication of functional self-assembled monolayers [6][7][8] that are reminiscent of the ordered supramolecular arrangements that can be formed on the surfaces of bulk (3D) materials. [9] However, isolating individual molecules is more challenging. [10] In contrast, new possibilities for templating emerge from nanostructuring that

Spintronic phenomena underpin new device paradigms for data storage and sensing. Scaling these down to the single molecule level requires controlling the properties of current-carrying molecular orbitals to enable access to spin states through phenomena such as inelastic electron tunnelling. Here we show that the spintronic properties of a tunnel junction containing a single molecule can be controlled using the local environment as a pseudo-gate. For tunnelling through iron phthalocyanine (FePc) on an insulating copper nitride (CuN) monolayer above Cu(001), we find that spin transitions may be strongly excited depending on the binding site of the central Fe atom. Different interactions between the Fe and the underlying Cu or N atoms shift the Fe d orbitals with respect to the Fermi energy and control the relative strength of the spin excitations; this effect is captured in a simple co-tunnelling model. This work demonstrates the importance of the atomic-scale environment for the development of single molecule spintronic devices.

No abstract