Materials Literature
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Computer simulations of a polymer chain of length N strongly adsorbed at the solid-liquid interface in the presence of explicit solvent are used to delineate the factors affecting the N dependence of the polymer lateral diffusion coefficient, D(||). We find that surface roughness has a large influence, and D(||) scale…
The transient currents induced by an applied direct voltage (dc) electric field have been measured liquid-crystal cells in nematic phase. The experimental results show that the addition of insulating nanoparticles, such as diamond powders, leads to a reduction of the ion concentration in cells so as to drastically red…
Photon recycling in strain-balanced quantum well solar cells grown on distributed Bragg reflectors has been observed as a suppression of the dark current and a change in electroluminescence spectra. Comparing devices grown with and without distributed Bragg reflectors we have demonstrated up to a 33% reduction in the…
Formation of condensed films of nanoparticles having small ratio of metal-core-diameter to organic-shell-thickness is desired for several applications in nanotechnology. We report here results of a X-ray scattering study carried out to understand structure and morphology of monolayer of such nanoparticles having gold-…
Extended x-ray absorption fine structure (EXAFS) has been measured from liquid helium to ambient temperature at the $\mathrm{Cu}\phantom{\rule{0.2em}{0ex}}K$ edge of copper chloride (CuCl) to investigate the local origin of negative thermal expansion. A quantitative analysis of the first coordination shell, performed…
The authors report structural, magnetic, and electrical properties of parasitic phase-free, well-ordered epitaxial La2CoMnO6 films. Despite their single ferromagnetic transition around 240K, they demonstrate that they possess a bidomain structure with distinct magnetic characteristics. The B-site ordering in the films…
By employing polarization- and temperature-dependent near-edge x-ray-absorption fine structure (NEXAFS) studies, we show that vertically aligned carbon nanotubes when subjected to low-pressure radio-frequency (rf) glow discharge can easily be doped with nitrogen atoms at predominantly graphitelike substitutional sites…
The authors have observed highly circularly polarized electroluminescence from organic light-emitting diodes (OLEDs) using wide-band reflector consisting of three-layered left-handed polymeric cholesteric liquid crystal (PCLC) films. By simply attaching the wide-band reflective PCLC reflector to a conventional OLED, t…
Negative thermal expansion (NTE) is known in ${\mathrm{Cu}}_{2}\mathrm{O}$ below $300\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ and in ${\mathrm{Ag}}_{2}\mathrm{O}$ up to its decomposition temperature of about $500\phantom{\rule{0.3em}{0ex}}\mathrm{K}$. Inelastic neutron scattering measurements in ${\mathrm{Cu}}_{2}\mathr…
In gold nanoparticles (Au NPs) capped with dodecanethiol (DT), the authors report the observation of superparamagnetic blocking temperature TB≃50K in D≃5nm NPs but only diamagnetism in 12nm NPs. For T<TB=50K, the strong temperature dependence of coercivity Hc, saturation magnetization Ms, and exchange bias He (…
The authors demonstrate surface-enhanced Raman scattering (SERS) detection on an optofluidic chip. Interconnected solid- and liquid-core antiresonant reflecting optical waveguides (ARROWs) form a planar beam geometry that allows for high mode intensities along microfluidic channels containing molecules optimized for S…
Modeling the consequences of crystalline defects requires efficient interaction sampling. Empirical potentials can identify relevant pathways if the energetics and configurations of competing defects are captured. Here, we develop such a potential for an alloy of arbitrary point defect concentration, body-centered cub…
In order to better utilize the superior transverse piezoelectric properties of [011] poled (1−x)Pb(Mg1∕3Nb2∕3)O3–xPbTiO3 single crystals with the composition near the morphotropic phase boundary, a complete set of elastic, dielectric, and piezoelectric constants of [011] poled 0.71Pb(Mg1∕3Nb2∕3)O3–0.29PbTiO3 single cr…
The authors study the magnetocaloric effect and refrigerant capacity of Ho30Y26Al24Co20, Dy50Gd7Al23Co20, and Er50Al24Co20Y6 bulk metallic glasses. Their magnetic entropy changes associated with spin glass to paramagnetic transition are larger than those of Gd, Gd5Si2Ge1.9Fe0.1, and many other intermetallic compounds…
The authors report on the ferromagnetic ordering in 1.86at.% Cu-doped ZnO nanocrystals synthesized by a solvothermal route. The distribution of Cu in ZnO lattice was inhomogeneous. In the Cu-poor cores, a spin-split acceptor impurity band model was proposed to explain the ferromagnetism. While in the Cu-rich surface l…
We investigated electronic structure of hexagonal multiferroic YMnO3 using the polarization dependent x-ray absorption spectroscopy (XAS) at O K and Mn L(2,3) edges. The spectra exhibit strong polarization dependence at both edges, reflecting anisotropic Mn 3d orbital occupation. Moreover, the O K edge spectra show th…
Further progress in the development of the remarkable electrochemical, electron field emission, high-temperature diode, and optical properties of $n$-type ultrananocrystalline diamond films requires a better understanding of electron transport in this material. Of particular interest is the origin of the transition to…
Vortex-antivortex pairs are localized excitations and have been found to be spontaneously created in magnetic elements. In the case that the vortex and the antivortex have opposite polarities the pair has a nonzero topological charge, and it behaves as a rotating vortex dipole. We find theoretically, and confirm numer…
We find that layered materials composed of various oxides of cations with s 2 electronic configuration, XY 2 O 4 , X = In or Sc, Y = Ga, Zn, Al, Cd and/or Mg, exhibit isotropic electron effective mass which can be obtained via averaging over those of the corresponding single-cation oxide constituents. This effect is d…
We report the observation of the spin valve effect in (Ga,Mn)As/p-GaAs/(Ga,Mn)As trilayer devices. Magnetoresistance measurements carried out in the current in plane geometry reveal positive magnetoresistance peaks when the two ferromagnetic layers are magnetized orthogonal to each other. Measurements carried out for…