Materials Literature
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The temperature dependence of the magnetic specific heat has been studied experimentally and theoretically in the semimagnetic semiconductor Pb_{1-x}Eu_{x}Te for x=0.027 and x=0.073, over the temperature range from 0.5 K to 10 K, in magnetic fields up to 2 T. There was a maximum in the magnetic specific heat between 1…
A new group-IV ferromagnetic semiconductor, Ge1-xFex, was successfully grown by low-temperature molecular beam epitaxy (LT-MBE) without precipitation of ferromagnetic Ge-Fe intermetallic compounds. The ferromagnetism of Ge1-xFex films was investigated by magnetic circular dichroism (MCD). In particular, the influence…
We have investigated the contact resistance of rubrene single-crystal field-effect transistors (FETs) with Nickel electrodes by performing scaling experiments on devices with channel length ranging from 200 nm up to 300 $μ$m. We find that the contact resistance can be as low as 100 $Ω$cm with narrowly spread fluctuati…
A new family of two- and three-dimensional photonic crystals with the symmetry of the kagome and pyrochlore lattices that exhibit interesting photonic band structures are reported. From large complete photonic band gaps in three dimensions to enormous partial gaps in two dimensions for certain polarizations occurring…
The magnetic properties of RNi4Ga (R = La, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm and Lu) compounds have been investigated. These compounds form in a hexagonal CaCu5 type structure with a space group P6/mmm. Compounds with the magnetic rare earths, R = Nd, Sm, Gd, Tb, Dy, Ho, Er and Tm, undergo a ferromagnetic transition…
The comparison of the single-particle (SP) dynamics between the whisker and ring NbSe$_3$ crystals provides new insight into the phase transition properties in quasi-one-dimensional charge density wave (CDW) systems.
We reexamine the mechanism of ferromagnetism in doped ${\mathrm{TiO}}_{2}$ anatase, using epitaxial $\mathrm{Cr}\ensuremath{\mathbin:}{\mathrm{TiO}}_{2}$ with excellent structural quality as a model system. In contrast to highly oriented but defective $\mathrm{Cr}\ensuremath{\mathbin:}{\mathrm{TiO}}_{2}$ ($\ensuremath…
Using electron diffraction on freestanding single-walled carbon nanotubes, we have determined the structural indices (n,m) of tubes in the diameter range from 1.4 to 3 nm. On the same freestanding tubes, we have recorded Raman spectra of the tangential modes and the radial breathing mode. For the smaller diameters (1.…
Cleaving crystals in a vacuum chamber is a simple method for obtaining atomically flat and clean surfaces for materials that have a preferential cleaving plane. Most in-situ cleavers use parallel cutting edges that are applied from two sides on the sample. We found in ambient experiments that diagonal cutting pliers,…
Measuring the Doppler broadening of the positron annihilation radiation or the angular correlation between the two annihilation gamma quanta reflects the momentum distribution of electrons seen by positrons in the material.Vacancy-type defects in solids localize positrons and the measured spectra are sensitive to the…
We have discovered superconductivity in the two-layer semiconducting monochalcogenide heterostrutures PbTe/PbS, PbTe/PbSe and PbTe/YbS. By comparing data from two-layer samples with data from single monochalcogenide films we conclude that the superconductivity is connected with the interface between the two semiconduc…
We report on the results of x-ray absorption, x-ray magnetic circular dichroism (XMCD), and photoemission experiments on ${\mathrm{Zn}}_{1\ensuremath{-}x}{\mathrm{Co}}_{x}\mathrm{O}$ $(x=0.05)$ thin film, which shows ferromagnetism at room temperature. The XMCD spectra show multiplet structures, characteristic of the…
We study the exchange interactions in half-metallic Heusler alloys using first-principles calculations in conjunction with the frozen-magnon approximation. The Curie temperature is estimated within both mean-field (MF) and random-phase-approximation (RPA) approaches. For the half-Heusler alloys NiMnSb and CoMnSb, the…
Surface-enhanced Raman spectroscopy (SERS) is currently experiencing a renaissance in its development driven by the remarkable discovery of single molecule SERS (SMSERS) and the explosion of interest in nanophotonics and plasmonics. Because excitation of the localized surface plasmon resonance (LSPR) of a nanostructur…
It is shown that a pair of identical emitters (e.g. wire dipole antennas) in the focal points of a disc, made of left-handed metamaterial (a "perfect" lens), form a non-radiating electromagnetic configuration. The emitters are fed with voltages of equal magnitude and pi-out-of-phase. Detailed finite-difference time-do…
Abstract Ultrafine Pd nanoparticles with an extremely narrow distribution were prepared by sonochemical reduction of [Pd(NH3)4]2+ in the presence of 1-propanol. The average diameter of the particles was approximately 5 nm. These nanoparticles were extremely stable in the colloidal state, even in the absence of stabili…
New mono- and bis[4-(3-hydroxy-2-methyl-4-quinolinoyloxy)-2,2,6,6-tetramethylpiperidin-1-oxyl](meso-tetraphenylporphyrinato)yttrium(III) complexes have been synthesized, and the properties of the excited states generated by photoexcitation of porphyrin were studied by time-resolved (TR) and pulsed two-dimensional elec…
Abstract A reaction of copper acetate with a phosphate salt of pentadentate ligand yielded octadecanuclear complex, [Cu18(Hbeamp)6(PO4)8]·C3H7OH·24H2O (H3beamp = 2,6-bis[N-(2-hydroxyethyl)aminomethyl]-4-methylphenol), in which Cu(II) ions were bridged by alkoxo, phenoxo, and phosphate groups. Magnetic susceptibility m…
This paper describes the relatively simple modification of a light microscope to operate with ultraviolet-based optics. Using a 280 nm UV illumination source, protein microcrystals are readily visualized in gels made from hydrated bilayers of phospholipids. Non-colored proteins stand out as clearly as colored proteins…
This paper reports an improved headspace gas chromatography (HS-GC) technique for the determination of carboxyl group content in wood fibers. The method is based on phase reaction conversion HS-GC technique developed previously [Chai et al., Ind. Eng. Chem. Res. 2003, 42, 5440−5444], but with major modifications in re…