A detailed understanding of structure and stability of nanowires is critical for applications. Atomic resolution imaging of ultrathin single crystalline Au nanowires using aberration-corrected microscopy reveals an intriguing relaxation whereby the atoms in the close-packed atomic planes normal to the growth direction are displaced in the axial direction leading to wrinkling of the (111) atomic plane normal to the wire axis. First-principles calculations of the structure of such nanowires confirm this wrinkling phenomenon, whereby the close-packed planes relax to form saddle-like surfaces. Molecular dynamics studies of wires with varying diameters and different bounding surfaces point to the key role of surface stress on the relaxation process. Using continuum mechanics arguments, we show that the wrinkling arises due to anisotropy in the surface stresses and in the elastic response, along with the divergence of surface-induced bulk stress near the edges of a faceted structure. The observations provide new understanding on the equilibrium structure of nanoscale systems and could have important implications for applications in sensing and actuation.

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Electric field-induced "etching" of Cr film is a tip-based patterning technique that is used to create micro-and nano-sized trenches in the film under ambient conditions. The experimental data obtained in this study reveals that the etching of Cr occurs via the formation of water-soluble CrO 3 , which spontaneously forms at the cathode tip when a large electric field is applied using a pointed tip in the presence of humid air. By varying experimental conditions, such as vacuum level, gaseous environment, temperature, and humidity, the kinetics of the electric field induced chemical reaction at the cathode was studied. Subsequently, the obtained insights were incorporated into a model to explain the mechanism of the phenomenon. Water vapor in the air surrounding the tip acts as a limiting reactant in the electrochemical oxidation of Cr to CrO 3. Insights obtained from this study open new avenues for technological improvements in the patterning technique using this chemical method.

In this work, a physically based analytical quantum linear threshold voltage model for short channel quad gate metal oxide semiconductor field effect transistors is developed. The proposed model, which is suitable for circuit simulation, is based on the analytical solution of three-dimensional Poisson and two-dimensional Schrödinger equation. Proposed model is fully validated against the professional numerical device simulator for a wide range of device geometries and also used to analyse the effect of geometry variation on the threshold voltage.

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In this paper, we present a simple and flexible non-interferometric method to generate various polarization singularity lattice fields. The proposed method is based on a double modulation technique that uses a single reflective spatial light modulator to generate different lattice structures consisting of  V-point and C-point polarization singularities. The present technique is compact with respect to previous experimental realization techniques. Different structures having star and lemon fields are generated without altering the experimental setup. In addition, the same setup can be used to obtain different types of inhomogeneous fields embedded with isolated polarization singularities even of higher orders. The Stokes polarimetry method has been used to obtain the polarization distributions of generated fields, which are in good agreement with simulated results.

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