Materials Literature
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We investigated spin-dependent transport in magnetic tunnel junctions made of III-V ${\mathrm{Ga}}_{1\ensuremath{-}x}{\mathrm{Mn}}_{x}\mathrm{As}$ electrodes and II-VI ZnSe tunnel barriers. The high tunnel magnetoresistance (TMR) ratio up to 100% we observed indicates high spin polarization at the barrier/electrodes i…
The density-of-states function of individual colloidal PbSe nanocrystals varying in diameter between 3 and 7 nm is measured by resonant tunneling spectroscopy. It is in semiquantitative agreement with tight-binding calculations, but the energy separation between electron (hole) levels of S and P symmetry is systematic…
Polypropyleneimine octaamine dendrimers were studied as an alternative means of generating highly crosslinked collagen. Crosslinking was effected by using the water-soluble carbodiimide 1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide hydrochloride (EDC). The multifunctional dendrimers were introduced as novel crosslin…
Selective nucleation of aragonite can be achieved at ambient conditions in water by using block copolymer microgels at a very low concentration (0.1 ppm). One polymer template particle is sufficient to control the nucleation of a ring of aragonite single crystals, which propagate into a sheaf structure (see SEM image)…
Gloss is a quantity used in the optical industry to quantify and categorize materials according to how well they scatter light specularly. With the aid of phase perturbation theory, we derive an approximate expression for this quantity for a one-dimensional randomly rough surface. It is demonstrated that gloss depends…
Using a super-operator formulation of linearized time-dependent density-functional theory, the dynamical polarizability of a system of interacting electrons is given a matrix continued-fraction representation whose coefficients can be obtained from the non-symmetric block-Lanczos method. The resulting algorithm allows…
Understanding how microorganisms influence the physical and chemical properties of the subsurface is hindered by our inability to observe microbial dynamics in real time and with high spatial resolution. Here, we investigate the use of noninvasive geophysical methods to monitor biomineralization at the laboratory scal…
We have studied the electronic structure of the diluted magnetic semiconductor ${\mathrm{Ga}}_{1\ensuremath{-}x}{\mathrm{Mn}}_{x}\mathrm{N}$ ($x=0.0$, 0.02, and 0.042) grown on Sn-doped $n$-type GaN using photoemission and soft x-ray absorption spectroscopy. Mn $L$-edge x-ray absorption have indicated that the Mn ions…
Two insulating phases of $\mathrm{Sr}\mathrm{Fe}{\mathrm{O}}_{3\ensuremath{-}\ensuremath{\delta}}$ have been found by the introduction of oxygen deficiencies in metallic $\mathrm{Sr}\mathrm{Fe}{\mathrm{O}}_{3}$, one with $0.15\ensuremath{\leqslant}\ensuremath{\delta}\ensuremath{\leqslant}0.19$ (Sample A) and the other…
Following the recent discussion on the puzzling nature of the interactions in the nanotubular system Na2V3O7, we present a detailed ab-initio microscopic analysis of its electronic and magnetic properties. By means of a non-trivial downfolding study we propose an effective model in terms of tubes of nine-site rings wi…
A protein conformation transition from random coil and/or helical conformation to beta-sheet is known to be central to the process used by silk-spinning spiders and insects to convert concentrated protein solutions to tough insoluble threads. Several factors including pH, metallic ions, shear force, and/or elongationa…
Magnesium alanate $\mathrm{Mg}{(\mathrm{Al}{\mathrm{H}}_{4})}_{2}$ has recently raised interest as a potential material for hydrogen storage. We apply ab initio calculations to characterize structural, electronic and energetic properties of $\mathrm{Mg}{(\mathrm{Al}{\mathrm{H}}_{4})}_{2}$. Density functional theory ca…
Alkali halide (100) crystal surfaces are anomalous, being very poorly wetted by their own melt at the triple point. We present extensive simulations for NaCl, followed by calculations of the solid-vapor, solid-liquid, and liquid-vapor free energies showing that solid NaCl(100) is a nonmelting surface, and that its ful…
This study deals with the spin wave spectrum in magnetic macrostructure (composed of two ferromagnetic materials) showing a 3D periodicity: spherical ferromagnetic grains disposed in the nodes of a simple cubic crystal lattice are embedded in a matrix with different ferromagnetic properties. It is shown that the \text…
In this paper we present a theoretical analysis of the effect of anomalies of the Fermi surface (FS) curvature on oscillations in the electron density of states (DOS) in strong magnetic fields. It is shown that the oscillations could be significantly strengthened when the FS curvature turns zero in the vicinities of s…
The thermal depoling behavior of several different Aurivillius phase ferroelectric ceramics has been studied. This includes two-layer (CaBi2Nb2O9,Ca0.9Ba0.1Bi2Nb2O9,Bi3NbTiO9,Bi3Nb1.2Ti0.8O9), three-layer (Bi4Ti3O12), and four-layer [CaBi4Ti4O15,Ca0.94(Na,Ce)0.03Bi4Ti4O15] compounds. All of them have a high Curie poin…
Spectra of one-particle and collective excitations in narrow-band ferromagnets with unquenched orbital moments are calculated in various theoretical models. The interaction of spin and orbital excitations with conduction electrons results in the damping of the former which, however, turns out to be rather small; there…
In the summary the results of experimental research of the dispersed media dielectric properties /spl epsiv/ and tg/spl delta/, in wide microwave band 2.5-3.5, 5.6-8.3 and 8-12 GHz, as a specimens of water foam, which are located in sections of rectangular waveguides are presented. The characteristics of absorption an…
Stress migration (SM) reliability of wide copper (Cu) interconnects with gouging vias was studied using a via chain structure stressed at temperatures ranging from 150/spl deg/C to 200/spl deg/C. After a 1000-hour SM test, via chain structures at the edge of the wafer were observed to have extremely high resistance du…
The use of hydrogel beads for the crystallization of proteins is explored in this contribution. The dynamic behaviour of the internal precipitant, protein concentration and relative supersaturation in a gel bead upon submerging the bead in a precipitant solution is characterized theoretically using a transient diffusi…