Magneto-ionics, understood as voltage-driven ion transport in magnetic materials, has largely relied on controlled migration of oxygen ions. Here, we demonstrate room-temperature voltage-driven nitrogen transport (i.e., nitrogen magneto-ionics) by electrolyte-gating of a CoN film. Nitrogen magneto-ionics in CoN is compared to oxygen magneto-ionics in Co3O4. Both materials are nanocrystalline (face-centered cubic structure) and show reversible voltage-driven ON-OFF ferromagnetism. In contrast to oxygen, nitrogen transport occurs uniformly creating a plane-wave-like migration front, without assistance of diffusion channels. Remarkably, nitrogen magneto-ionics requires lower threshold voltages and exhibits enhanced rates and cyclability. This is due to the lower activation energy for ion diffusion and the lower electronegativity of nitrogen compared to oxygen. These results may open new avenues in applications such as brain-inspired computing or iontronics in general.

Vertically aligned multiwall carbon nanotubes were grown by water-assisted chemical vapor deposition on a large-area lithium tantalate pyroelectric detector. The processing parameters are nominally identical to those by which others have achieved the "world's darkest substance" on a silicon substrate. The pyroelectric detector material, though a good candidate for such a coating, presents additional challenges and outcomes. After coating, a cycle of heating, electric field poling, and cooling was employed to restore the spontaneous polarization perpendicular to the detector electrodes. The detector responsivity is reported along with imaging as well as visible and infrared reflectance measurements of the detector and a silicon witness sample. We find that the detector responsivity is slightly compromised by the heat of processing and the coating properties are substrate dependent. However, it is possible to achieve nearly ideal values of detector reflectance uniformly less than 0.1% from 400 nm to 4 microm and less than 1% from 4 to 14 microm.

Platinum clusters supported on KL zeolites were characterized by EPR, HRTEM, and EXAFS. Two kinds of hydrogen chemisorption experiments both result in a saturation value of 2.9 hydrogen atoms per platinum atom, significantly more than that reported so far. A hydrogen coverage-dependent cluster restructuring is suggested.

We study electrical properties and breakdown phenomena in metal/aluminum oxide/metal and electrolyte/aluminum oxide/metal contacts, with the aim to achieve a better understanding of failure modes and improve the performance of model electrowetting systems. Electrical conduction in anodic aluminum oxide dielectrics is dominated by the presence of electrically active trapping sites, resulting in various conduction mechanisms being dominant within distinct voltage ranges until hard breakdown occurs. Breakdown voltage depends on its polarity, due to the formation of a p-in junction within the oxide; such asymmetric behavior tends to disappear at larger oxide thickness. Electrolyte/dielectric contacts present an even more pronounced asymmetry in breakdown characteristics: a cathodic bias results in breakdown at low voltage, while under anodic bias high field ionic conduction starts before breakdown occurs. These phenomena are interpreted in terms of electrochemical reactions occurring at the surface: cathodic processes contribute to oxide dissolution and failure, while anodic processes result in additional oxide growth before breakdown. V

Recent experiments have shown the viability of the metamaterial approach to dielectric response engineering for enhancing the transition temperature, Tc, of a superconductor. In this report, we demonstrate the use of Al2O3-coated aluminium nanoparticles to form the recently proposed epsilon near zero (ENZ) core-shell metamaterial superconductor with a Tc that is three times that of pure aluminium. IR reflectivity measurements confirm the predicted metamaterial modification of the dielectric function thus demonstrating the efficacy of the ENZ metamaterial approach to Tc engineering. The developed technology enables efficient nanofabrication of bulk aluminium-based metamaterial superconductors. These results open up numerous new possibilities of considerable Tc increase in other simple superconductors.