Materials Literature
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Doping of the band insulator FeS$_2$ with Co on the Fe site introduces a small density of itinerant carriers and magnetic moments. The lattice constant, AC and DC magnetic susceptibility, magnetization, and specific heat have been measured over the $0\le x\le 0.085$ range of Co concentration. The variation of the AC s…
We have investigated the effects of substituting In for Mn on the antiferromagnetic phase transition in YMnO3 using magnetic, dielectric, and specific heat measurements. We prepared a set of isostructural phase pure hexagonal YMn$_{1-x}$In$_{x}$O$_{3}$ samples having x=0 to x=0.9, which exhibit a systematic decrease o…
We have investigated Au atomic contacts in H$_{2}$ and D$_{2}$ environment by conductance measurement and $dI/dV$ spectroscopy. A single H$_{2}$ or D$_{2}$ molecule was found to bridge Au electrodes. In the case of the Au/H$_{2}$/Au junction, symmetric peaks were observed in $dI/dV$ spectra, while they were not observ…
Angular dependent core-hole screening effects have been found in the cobalt K-edge x-ray absorption spectrum of LiCoO2, using high-resolution data and parameter-free GGA+U calculations. The Co 1s core-hole on the absorber causes strong local attraction. The core-hole screening on the nearest neighbours cobalt induces…
We report electrical, magnetic, magnetodielectric, and magnetoabsorption properties of a polycrystalline GaFeO3. The resistivity measurement shows that the sample is highly insulating below 200 K and the resistivity above 200 K obey the Arrhenius law with an activation energy of Ea=0.67 eV. An anomaly occurs in the te…
Heusler alloy Co2FeAl was employed as ferromagnetic layers in Co2FeAl (3nm)∕Ru (xnm)∕Co2FeAl (5nm) synthetic antiferromagnet structures. The experimental results show that the structure with a Ru thickness of 0.45nm is strongly antiferromagnetic coupled, which is maintained after annealing at 150°C for 1h. The structu…
We investigate the phase diagrams of RMn(2)O(5) via a first-principles effective-Hamiltonian method. We are able to reproduce the most important features of the complicated magnetic and ferroelectric phase transitions. The calculated polarization as a function of temperature agrees very well with experiments. The diel…
Onionlike mesoporous carbon and carbon–silica nanocomposites with multilayer vesicle structures can be synthesized by an organic–inorganic co-assembly method under hydrothermal conditions in an aqueous emulsion solution (see figure). The nanocomposite vesicles have ordered lamellar mesostructures with about 3–9 layers…
(Gd 1− x Eu x ) 2 Zr 2 O 7 (0≤ x ≤1.0) ceramics are prepared via a solid‐state reaction process at 1973 K for 10 h in air. (Gd 1− x Eu x ) 2 Zr 2 O 7 (0.2≤ x ≤1.0) ceramics exhibit an ordered pyrochlore‐type structure; however, Gd 2 Zr 2 O 7 has a disordered defect fluorite‐type structure. Raman spectroscopy analysis…
We performed ab initio density-functional theory calculations to investigate the process of hydrogenation of a bilayer of graphene. 50% hydrogen coverage is possible in case that the hydrogen atoms are allowed to adsorb on both sides of the bilayer. In this case interlayer chemical bonding occurs which stabilizes the…
Abstract Porous polymer films that can be employed for broadband and omnidirectional antireflection coatings are successfully shown. These films form a gradient‐refractive‐index structure and are achieved by spin‐coating the solution of a polystyrene‐block‐poly(methyl methacrylate) (PS‐b‐PMMA)/PMMA blend onto an octad…
Low-energy electron microscopy reveals a mode of graphene growth on Ru(0001) in which Ru atoms are etched from a step edge and injected under a growing graphene sheet. Based on density-functional calculations, we propose a model wherein injected Ru atoms form metastable islands under the graphene. Scanning tunneling m…
Time-resolved and temperature-dependent photoluminescence measurements on one-dimensional sexithiophene lattices reveal intrinsic branching of photoexcitations to two distinct species: self-trapped excitons and dark charge-transfer excitons (CTX; > 5% yield), with radii spanning 2-3 sites. The significant CTX yield re…
We report measurements of structural phase transition of four parent compounds $R\text{FeAsO}$ ($R=\text{La}$, Sm, Gd, and Tb) by means of low-temperature x-ray diffraction (XRD). Magnetic transition temperatures associated with Fe ions $({T}_{N1})$ are also determined from the temperature dependence of resistivity. A…
The Hall effect and resistivity of the carrier doped magnetic semiconductor Fe$_{1-x}$Co$_x$S$_2$ were measured for $0\le x \le 0.16$, temperatures between 0.05 and 300 K, and fields of up to 9 T. Our Hall data indicate electron charge carriers with a density of only 10 to 30% of the Co density of our crystals. Despit…
We have observed a quadratic x-ray magneto-optical effect in near-normal incidence reflection at the M-edges of iron. The effect appears as the magnetically induced rotation of ca. 0.1$ degrees of the polarization plane of linearly polarized x-ray radiation upon reflection. A comparison of the measured rotation spectr…
Despite the growing interest of quantum dots (QDs) in biological applications, there are many concerns regarding the potential accumulation and toxic effects of Cd-containing QDs in animals and humans. Zinc oxide QDs are promising alternatives for diagnosis and imaging but their aqueous instability has markedly limite…
Spray processable blue electrochromic polymers with strictly alternating “donor-acceptor” copolymers are reported that exhibit saturated blue neutral states, highly transmissive oxidized states, excellent optical contrasts, fast switching times, and long-term redox switching stability. In addition, an alkylester-funct…
We report the X-ray attenuation property of dendrimer-entrapped gold nanoparticles (Au DENPs) that could be used as a computed tomography (CT) contrast agent. Amine-terminated generation 5 (G5.NH 2 ) poly(amidoamine) dendrimers were used as templates to complex AuCl 4 − ions for subsequent reductive formation of Au DE…
Abstract Biological photonic systems composed of anhydrous guanine crystals evolved separately in several taxonomic groups. Here, two such systems found in fish and spiders, both of which make use of anhydrous guanine crystal plates to produce structural colors, are examined. Measurements of the photonic‐crystal struc…