Unconventional Magnetism in a Nitrogen-Based Analogue of Cupric Oxide

We have investigated the magnetic properties of CuNCN, the first nitrogen-based analogue of cupric oxide, CuO. Our muon spin relaxation, nuclear magnetic resonance and electron spin resonance studies reveal that classical magnetic ordering is absent down to lowest temperatures. However, large enhancement of spin correlations and unexpected inhomogeneous magnetism have been observed below 80 K. We attribute this to a peculiar fragility of the electronic state against weak perturbations due to geometrical frustration, which selects between competing spin-liquid and more conventional frozen states.Comment: 4 pages + 1 page of supplementary information, accepted for publication in PR

Femtosecond laser-induced hard X-ray generation in air from a solution flow of Au nano-sphere suspension using an automatic positioning system

Femtosecond laser-induced hard X-ray generation in air from a 100-μm-thick solution film of distilled water or Au nano-sphere suspension was carried out by using a newly-developed automatic positioning system with 1-μm precision. By positioning the solution film for the highest X-ray intensity, the optimum position shifted upstream as the laser power increased due to breakdown. Optimized positioning allowed us to control X-ray intensity with high fidelity. X-ray generation from Au nano-sphere suspension and distilled water showed different power scaling. Linear and nonlinear absorption mechanism are analyzed together with numerical modeling of light delivery

Diamond: a gem for micro-optics

Photonics have developed greatly over the last several decades and brought about a variety of new concepts in communica tions, sensing, solar energy and many other fields. With the emerging applications of quantum technologies and all optical data processing, the impact of photonics on technology is unde niable, as evidenced through the International Year of Light and Light based Technologies in 2015.NANOSCIENCE FOUNDRIES AND FINE ANALYSIS - EUROP

Design concept of a hybrid photo-voltaic/thermal conversion cell for mid-infrared light energy harvester

© 2017 Optical Society of America. Harvesting the thermal loss energy emitted as electro-magnetic (EM) waves (at solar, micrometer and millimeter spectral wavelengths) over the broadest possible spectral range is a major target in the development of sustainable energy solutions. Solar cells and rectennas suffer unavoidable energy losses due to heat generation as well as due to the transparency window (λ > 1100 nm for Si), which is not utilized in photo-electrical conversion. A hybrid photovoltaic/thermoelectric conversion system is presented as an extension of a typical Si solar cell and demonstrates additional capability in harvesting energy over the entirety of the solar spectrum. Nano-textured silicon - black-Si - was used to reduce reflectivity of the cell surface and a Ge-Sn layer was added below to facilitate absorption over the IR wing of the solar spectrum. An up to 7% improvement to the voltage generated by photo-voltaic conversion was obtained via the thermal-to-electrical contribution

Nano-rescaling of gold films on polystyrene: Thermal management for SERS

© The Royal Society of Chemistry 2017. Nano-textured Au surfaces were prepared on pre-stretched 2D polystyrene (PS) sheets sputtered with different thicknesses of Au. The Au-coated PS was subjected to thermal annealing above the glass transition temperature at ∼150 °C, thus undergoing surface area rescaling via a volume phase transition. The yellow color of the Au changed from the typical mirror-like appearance to a diffusive dark yellow, progressing to dark brown at the smallest feature size, hence, electromagnetic energy was coupled into the substrate. While the surface area footprint is the same after shrinking the PS, the roughness can be modified from the nano- to the micro-scale for different initial thicknesses of sputtered Au. The nanometer-sized features of surface wrinkles on the Au films make them suitable for surface-enhanced Raman scattering (SERS) sensors that can reach ∼104 counts per s per mW. The thermal diffusivity of the contracted surfaces was determined by a non-contact temperature wave method and was larger than that of PS (α ≃ 1.1 × 10-7 m2 s-1) with a linear scaling on the Au thickness: each 10 nm addition of Au increased the diffusivity by 4%. This allows improved heat dissipation from the laser irradiated spot during SERS measurements

Plasmonic hydrogen sensor at infrared wavelengths

We have investigated the variations in the transmission spectra of nanodiscs as well as metal hole array plasmonic structures as a result of the hydrogen adsorption-desorption processes. The structures have been shown to be a viable platform for all-optical hydrogen sensing in the infrared. In cases of both nanodisc and metal hole arrays, upon exposure to hydrogen, a redshift of the plasmon resonance band was observed. Response time as well as the magnitude of the spectral shift was similar for both plasmonic structure types

Tipping solutions: Emerging 3D nano-fabrication/-imaging technologies

© 2017, Gediminas Seniutinas, Saulius Juodkazis et al. The evolution of optical microscopy from an imaging technique into a tool for materials modification and fabrication is now being repeated with other characterization techniques, including scanning electron microscopy (SEM), focused ion beam (FIB) milling/imaging, and atomic force microscopy (AFM). Fabrication and in situ imaging of materials undergoing a three-dimensional (3D) nano-structuring within a 1-100 nm resolution window is required for future manufacturing of devices. This level of precision is critically in enabling the cross-over between different device platforms (e.g. from electronics to micro-/nano-fluidics and/or photonics) within future devices that will be interfacing with biological and molecular systems in a 3D fashion. Prospective trends in electron, ion, and nano-tip based fabrication techniques are presented