0000000000787694
AUTHOR
Henny W. Zandbergen
Phase Transitions in Spin-Crossover Thin Films Probed by Graphene Transport Measurements
Future multi-functional hybrid devices might combine switchable molecules and 2D material-based devices. Spin-crossover compounds are of particular interest in this context since they exhibit bistability and memory effects at room temperature while responding to numerous external stimuli. Atomically-thin 2D materials such as graphene attract a lot of attention for their fascinating electrical, optical, and mechanical properties, but also for their reliability for room-temperature operations. Here, we demonstrate that thermally-induced spin-state switching of spin-crossover nanoparticle thin films can be monitored through the electrical transport properties of graphene lying underneath the f…
Downsizing of robust Fe-triazole@SiO2 spin-crossover nanoparticles with ultrathin shells
A chemical protocol to design robust hybrid [Fe(Htrz)2(trz)](BF4)@SiO2 nanoparticles (NPs) with sizes as small as 28 nm and ultrathin silica shells below 3 nm has been developed. These NPs present a characteristic abrupt spin transition with a subsequent decrease in the width of the thermal hysteresis upon reducing the NP size.
Spin switching in electronic devices based on 2D assemblies of spin-crossover nanoparticles
In this communication we study the transport properties of two-dimensional assemblies of [Fe(Htrz)2(trz)](BF4) spin-crossover nanoparticles (NPs) with two different morphologies. The NPs have been synthesized made in a similar manner than in our previous study in which single NPs were measured. We prepared free-standing self-assembled monolayer sheets of both SCO NPs formed at the air/liquid interface on holey carbon TEM grids to extract their global arrangement and NP size distributions by STEM-HAADF technique. The SCO NP systems present a rod-like shape and possess two different volumes, corresponding to lengths of 25 nm and 44 nm along the rod direction and average diameters of 10 nm and…
Strategies for structure solution and refinement of small organic molecules from electron diffraction data and limitations of the simulation approach
In recent years, a series of non-linear optically active bis(benzylidene) ketones have been synthesized and investigated by electron crystallography. In most cases, structure refinement was possible by combining electron diffraction analysis and quantum-mechanical calculations with maximum-entropy methods. However, when the torsional angles between the phenyl rings and the C=C double bonds are strongly affected by the crystal field, this method fails because packing-energy calculations are not sufficiently sensitive. This problem can be solved by refining the approximate model with SHELXL, if the data set is sufficiently accurate and the model close to the correct structure. Here it is show…
Extreme sensitivity of superconductivity to stoichiometry in Fe1+?Se
The recently discovered iron arsenide superconductors appear to display a universal set of characteristic features, including proximity to a magnetically ordered state and robustness of the superconductivity in the presence of disorder. Here we show that superconductivity in Fe1+?Se, which can be considered the parent compound of the superconducting arsenide family, is destroyed by very small changes in stoichiometry. Further, we show that nonsuperconducting Fe1+?Se is not magnetically ordered down to 5 K. These results suggest that robust superconductivity and immediate instability against an ordered magnetic state should not be considered as intrinsic characteristics of iron-based superco…