Molecular switching by proton-coupled electron transport drives giant negative differential resistance.

To develop new types of dynamic molecular devices with atomic-scale control over electronic function, new types of molecular switches are needed with time-dependent switching probabilities. We report such a molecular switch based on proton-coupled electron transfer (PCET) reaction with giant hysteric negative differential resistance (NDR) with peak-to-valley ratios of 120 ± 6.6 and memory on/off ratios of (2.

Sub-micrometer four-point probe transport measurements on graphene.

Usually, electronic transport measurements on two-dimensional materials, such as graphene and transition metal dichalcogenides, require deposition of electrodes on top of the material, in, for instance, the form of a Hall bar device. In this work, we show that by making use of a collinear micro-four-point probe, electrical transport measurements on small flakes of graphene can be performed without having to fabricate electrodes on top of the flakes. Using probes with probe pitches down to sub-micrometer scale, we show back-gate tuned transport measurements in graphene on silicon oxide and on hexagonal boron nitride.

Presolidification in Eutectic Droplets.

Evidence of presolidification, the counterpart to premelting, is reported. Near the eutectic temperature, T_{C}, the propagation direction of thermal gradient driven motion of eutectic Ge-Pt droplets on Ge(110) is determined by presolidification. Well above T_{C}, the micron-sized droplets move towards the hottest location at the substrate, irrespective of crystalline direction.

Photoconductivity Enhancement in Atomically Thin Molybdenum Disulfide through Local Doping from Confined Water.

Two-dimensional transition metal dichalcogenide (TMDC) materials have shown great potential for usage in opto-electronic devices, especially down to the regime of a few layers to a single layer. However, at these limits, the material properties can be strongly influenced by the interfaces. By using photoconductive atomic force microscopy, we show a local enhancement of photoconductivity at the nanoscale in bilayer molybdenum disulfide on mica, where water is confined between the TMDC and the substrate.