Materials Literature
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We have measured the pressure-volume (P-V) relations for cubic iron-nickel alloys for three different compositions: Fe 0.64Ni (0.36), Fe 0.55Ni (0.45), and Fe 0.20Ni (0.80). It is observed that for a certain pressure range the bulk modulus does not change or can even decrease to some minimum value, after which it begi…
The structure and magnetic properties of Y2Al3Fe14−xMnx (x=0–12) compounds have been investigated by means of x-ray diffraction and magnetization measurements. The Y2Al3Fe14−xMnx compounds have a hexagonal Th2Ni17-type structure. Their unit-cell volumes increase slowly with increasing x first, then increases rapidly w…
Spin-charge-orbital ordered structures in doped layered manganites are investigated using an orbital-degenerate double-exchange model tightly coupled to Jahn-Teller distortions. In the ferromagnetic phase, unexpected diagonal stripes at $x\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}1/m$ ( $m\phantom{\rule{0ex}{…
The two-electron $(2e)$ doped ${\mathrm{Ca}}_{1\ensuremath{-}x}{\mathrm{Ce}}_{x}{\mathrm{MnO}}_{3}$ $(0<~x<~0.2)$ system was prepared by sol-gel method and investigated by x-ray absorption spectroscopy (XAS), X-ray diffraction, and temperature and field dependent magnetic and transport measurements. The results…
The spectrum of the luminescence emitted at the collapse of single laser-induced bubbles in water is measured for different maximum bubble radii. Bubbles as large as 2 mm show a molecular OH(*) band at 310 nm in the spectrum, which otherwise can be fitted approximately with a blackbody curve at a temperature of 7800 K…
We report on an experimental study of buffer mechanism in plasma-assisted molecular-beam epitaxy of ZnO on Al2O3(0001) with a MgO buffer. It lowers the surface energy and provides nucleation cores. As a result, lateral epitaxial growth of ZnO becomes favorable from the initial growth stage. The MgO buffer also affects…
The Fourier law for lattice heat conduction fails when the source of heat is small compared to the phonon mean free path. We provide experimental evidence for this effect using heating and electrical-resistance thermometry along a doped region in a suspended silicon membrane. The data are consistent with a closed-form…
Raman spectroscopy is used to infer elastic properties of single-wall carbon nanotubes (SWNTs) in composites. This letter presents strain-induced frequency shift of tangential Raman active modes of SWNTs embedded in epoxy resin subjected to bending. Epoxy curing and sample extension in the tensile strength test are fo…
The neutron scattering structure factor S(N)(Q) for a 40 mg drop of molten alumina (Al2O3) held at 2500 K, using a laser-heated aerodynamic levitation furnace, is measured for the first time. A 1700 atom model of liquid alumina is generated from these data using the technique of empirical potential structural refineme…
The first five members of the Srn+1TinO3n+1 Ruddlesden–Popper homologous series, i.e., Sr2TiO4, Sr3Ti2O7, Sr4Ti3O10, Sr5Ti4O13, and Sr6Ti5O16, have been grown by reactive molecular beam epitaxy. A combination of atomic absorption spectroscopy and reflection high-energy electron diffraction intensity oscillations were…
We report the experimental results of the valence band offset at a ZnO/GaN (0001) heterointerface. The ZnO/GaN (0001) heterointerface is prepared by growing a ZnO layer on (0001) GaN/Al2O3, in which the ZnO layer is epitaxially deposited by plasma-assisted molecular-beam epitaxy, while the GaN template is prepared by…
A recent study determined the Young's modulus of carbon nanotubes by measuring resonance frequency and using the modulus-frequency relation resulting from the linear vibration theory. It leads to the report that the Young's modulus decreases sharply, from about 1 to 0.1 TPa with the diameter D increasing from 8 to 40…
We define Wannier functions for interacting systems, and show that the results on the localization of the Wannier functions for non-interacting systems carry over to the Wannier functions for interacting systems. In addition we demonstrate that the characterization of metals and insulators by the decay properties of t…
We present a first-principles analysis of the strain renormalization of the cation diffusivity on the GaAs(001) surface. For the example of In/GaAs(001)-c(4x4) it is shown that the binding of In is increased when the substrate lattice is expanded. The diffusion barrier ΔE(e) has a non-monotonic strain dependence with…
By using the dark-field real-space imaging technique of transmission electron microscopy (TEM), we have observed slow 200 A-scale fluctuations of charge-ordered (CO) phase in mixed-valent manganites under a strong electron beam irradiation. In addition to these unusual fluctuations of the CO phase, we observed the swi…
The Si(557)-Au surface, containing monatomic Au wires parallel to the steps, has been proposed as an experimental realization of an ideal one-dimensional metal. In fact, recent photoemission experiments on this system (Nature 402, 504 (1999)) found two peaks that were interpreted in terms of the spin-charge separation…
We have shown that polarized neutron reflectometry can determine in a model-free way not only the mean magnetization of a ferromagnetic thin film at any point of a hysteresis cycle, but also the mean square dispersion of the magnetization vectors of its lateral domains. This technique is applied to elucidate the mecha…
The Powder-In-Tube process has been employed to fabricate tape-like conductors with a strong metallic sheath and based on the newly discovered MgB2 superconducting phase. Long superconducting tapes have been prepared by packing reacted MgB2 powders inside pure Ag, Cu and Ni tubes which are then cold worked by drawing…
Ferromagnetic GaMnAs containing up to 10% Mn has been grown by migration-enhanced epitaxy at a substrate temperature of 150 °C. The lattice constant of hypothetical zinc-blende structure MnAs is determined to be 5.90 Å, which deviates somewhat from previously reported values. This deviation is ascribed to growth-condi…
This paper has been withdrawn by the authors, because of serious experimental problems.