Nanowire Acting as a Superconducting Quantum Interference Device

We present the results from an experimental study of the magneto-transport of superconducting wires of amorphous Indium-Oxide, having widths in the range 40 - 120 nm. We find that, below the superconducting transition temperature, the wires exhibit clear, reproducible, oscillations in their resistance as a function of magnetic field. The oscillations are reminiscent of those which underlie the operation of a superconducting quantum interference device.Comment: 4 pages, 4 figures, 1 tabl

Structural Development in Ge-Rich Ge-S Glasses

The Raman spectra of Ge-S glasses in the Ge-rich region from Ge 33 to 46 % have been investigated in order to know the structural development of the network glasses. From the detailed curve fits, we have found that there is an unassigned peak at 410 cm-1 and it becomes larger with increasing Ge composition. To clarify the structural origin of the peak, we virtually constructed the atomic arrangement of the glassy state starting from the crystalline state through the liquid state and changed the composition gradually depleting the medium in sulfur. From the consideration of the structural modeling and the atomic orbital theory, we suggest that single Ge-S chain is a probable structural origin of the peak

Ferroelectricity in Ultrathin Strained BaTiO\u3csub\u3e3\u3c/sub\u3e Films: Probing the Size Effect by Ultraviolet Raman Spectroscopy

We demonstrate a dramatic effect of film thickness on the ferroelectric phase transition temperature, Tc, in strained BaTiO3 films grown on SrTiO3 substrates. Using variable temperature ultraviolet Raman spectroscopy enables measuring Tc in films as thin as 1.6 nm, and film thickness variation from 1.6 to 10 nm leads to Tc tuning from 70 to about 925K. Raman data are consistent with synchrotron x-ray scattering results, which indicate the presence of of 180◦ domains below Tc, and thermodynamic phase-field model calculations of Tc as a function of thickness

Nanoscale Processing by Adaptive Laser Pulses

We theoretically demonstrate that atomically-precise ``nanoscale processing" can be reproducibly performed by adaptive laser pulses. We present the new approach on the controlled welding of crossed carbon nanotubes, giving various metastable junctions of interest. Adaptive laser pulses could be also used in preparation of other hybrid nanostructures.Comment: 4 pages, 4 Postscript figure

Interfacial coherency and ferroelectricity of BaTiO(3)/SrTiO(3) superlattice films

We studied the phase transitions, domain morphologies, and polarizations in BaTiO(3)/SrTiO(3) superlattices grown on SrTiO(3) substrates. Using the phase field approach, we discovered the remarkable influence of film/substrate interfacial coherency on the ferroelectricity of the SrTiO(3) layers within a superlattice: it is an orthorhombic ferroelectric for an incoherent interface while it exhibits only induced polarization by the adjacent BaTiO(3) layers for a coherent interface. We presented the domain morphologies within individual BaTiO(3) and SrTiO(3) layers which have different ferroelectric symmetries. The results are compared to ultraviolet Raman spectroscopy and variable temperature x-ray diffraction measurements.open312

Phase behavior and material properties of hollow nanoparticles

Effective pair potentials for hollow nanoparticles like the ones made from carbon (fullerenes) or metal dichalcogenides (inorganic fullerenes) consist of a hard core repulsion and a deep, but short-ranged, van der Waals attraction. We investigate them for single- and multi-walled nanoparticles and show that in both cases, in the limit of large radii the interaction range scales inversely with the radius, $R$, while the well depth scales linearly with $R$. We predict the values of the radius $R$ and the wall thickness $h$ at which the gas-liquid coexistence disappears from the phase diagram. We also discuss unusual material properties of the solid, which include a large heat of sublimation and a small surface energy.Comment: Revtex, 13 pages with 8 Postscript files included, submitted to Phys. Rev.

Prediction of ferroelectricity in BaTiO3/SrTiO3 superlattices with domains

The phase transitions of superlattices into single- and multidomain states were studied using a mesoscale phase-field model incorporating structural inhomogeneity, micromechanics, and electrostatics. While the predictions of transition temperatures of BaTiO3/SrTiO3 superlattices into multidomains show remarkably good, quantitative agreement with ultraviolet Raman spectroscopic and variable-temperature x-ray diffraction measurements, the single-domain assumption breaks down for superlattices in which the nonferroelectric layer thickness exceeds the characteristic domain size in the ferroelectric layers.open463

Tubular structures of GaS

In this Brief Report we demonstrate, using density-functional tight-binding theory, that gallium sulfide (GaS) tubular nanostructures are stable and energetically viable. The GaS-based nanotubes have a semiconducting direct gap which grows towards the value of two-dimensional hexagonal GaS sheet and is in contrast to carbon nanotubes largely independent of chirality. We further report on the mechanical properties of the GaS-based nanotubes

Epitaxial CrN Thin Films with High Thermoelectric Figure of Merit

A large enhancement of the thermoelectric figure of merit is reported in single-crystalline films of CrN. The mechanism of the reduction of the lattice thermal conductivity in cubic CrN is similar to the resonant bonding in IV–VI compounds. Therefore, useful ideas from classic thermo­electrics can be applied to tune functionalities in transition metal nitrides and oxides.Solid-State Solar-Thermal Energy Conversion Center (DE-SC0001299)Solid-State Solar-Thermal Energy Conversion Center (DE-FG02-09ER46577