Directly measuring the structural transition pathways of strain-engineered VO thin films.

Epitaxial films of vanadium dioxide (VO) on rutile TiO substrates provide a means of strain-engineering the transition pathways and stabilizing of the intermediate phases between monoclinic (insulating) M1 and rutile (metal) R end phases. In this work, we investigate structural behavior of epitaxial VO thin films deposited on isostructural MgF (001) and (110) substrates via temperature-dependent Raman microscopy analysis. The choice of MgF substrate clearly reveals how elongation of V-V dimers accompanied by the shortening of V-O bonds triggers the intermediate M2 phase in the temperature range between 70-80 °C upon the heating-cooling cycles.

Room Temperature Metallic Conductivity in a Metal-Organic Framework Induced by Oxidation.

Metal-organic frameworks (MOFs) containing redox active linkers have led to hybrid compounds exhibiting high electrical conductivity, which enables their use in applications in electronics and electrocatalysis. While many computational studies predict two-dimensional (2D) MOFs to be metallic, the majority of experiments show decreasing conductivity on cooling, indicative of a gap in the electronic band structure. To date, only a handful of MOFs have been reported that exhibit increased electrical conductivity upon cooling indicative of a metallic character, which highlights the need for a better understanding of the origin of the conductivity.

Scalable Memdiodes Exhibiting Rectification and Hysteresis for Neuromorphic Computing.

Metal-NbO-metal memdiodes exhibiting rectification, hysteresis, and capacitance are demonstrated for applications in neuromorphic circuitry. These devices do not require any post-fabrication treatments such as filament creation by electroforming that would impede circuit scalability. Instead these devices operate due to Poole-Frenkel defect controlled transport where the high defect density is inherent to the NbO deposition rather than post-fabrication treatments.