Materials Literature
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We have probed the local thermoelectric power of semiconductor nanostructures with the use of ultrahigh-vacuum scanning thermoelectric microscopy. When applied to a p-n junction, this method reveals that the thermoelectric power changes its sign abruptly within 2 nanometers across the junction. Because thermoelectric…
A paramagnetic muonium (Mu) state with an extremely small hyperfine parameter was observed for the first time in single-crystalline GaN below 25 K. It has a highly anisotropic hyperfine structure with axial symmetry along the [0001] direction, suggesting that it is located either at a nitrogen-antibonding or a bond-ce…
We demonstrate that the spin-polarized electron current can interact with a microwave electric field in a resonant manner. The spin-orbit interaction gives rise to an effective magnetic field proportional to the electric current. In the presence of both dc and ac electric field components, electron spin resonance occu…
Since Br adsorption on Au(100) displays an incommensurate ordered phase, a lattice-gas treatment of the adlayer configurations is not reliable. We therefore use density functional theory slab calculations to determine the parameters necessary for the construction of an off-lattice model. We compute and analyze the tot…
The temperature dependence of the Hall coefficient of a series of ferromagnetic Ga(1-x)Mn(x)As samples is measured in the temperature range 80K < T < 500K. We model the Hall coefficient assuming a magnetic susceptibility given by the Curie-Weiss law, a spontaneous Hall coefficient proportional to rho_xx^2(T), and incl…
The capability of the density functional broken symmetry approach for the calculation of various EPR parameters of exchange coupled metal clusters is demonstrated by studying the experimentally well-investigated [Mn(III)Mn(IV)(mu-O)(2)(mu-OAc)DTNE](2+) complex. Geometry optimizations of the complex in its broken symme…
We present a first principle computation of vertical stripes in $La_{15/8}Sr_{1/8}CuO_4$ within the LDA+U method. We find that Cu centered stripes are unstable toward O centered stripes. The metallic core of the stripe is quite wide and shows reduced magnetic moments with suppressed antiferromagnetic (AF) interactions…
We report a pulsed EPR study of the phase relaxation of electron spins bound to phosphorus donors in isotopically purified 29^Si and natural abundance Si single crystals measured at 8 K.
A class of materials known as ``ferroelectric metals'' was discussed theoretically by Anderson and Blount in 1965 [Phys. Rev. Lett. 14, 217 (1965)], but to date no examples of this class have been reported. Here we present measurements of the elastic moduli of Cd2Re2O7 through the 200 K cubic-to-tetragonal phase trans…
The ability to follow Moore's Law has been the basis of the tremendous success of the semiconductor industry in the past decades. To date, the greatest challenge for device scaling is the required replacement of silicon dioxide-based gate oxides by high-k oxides in transistors. Around 2010 high-k oxides are required t…
In the present paper we investigate the restriction conditions for three kinds of cavity resonators ({\it i.e.}, the rectangular, cylindrical, spherical resonators). It is shown that the layer of materials with negative optical refractive indices can act as a phase compensator/conjugator, and thus by combining such a…
We present measurements of electrical resistivity, thermal conductivity, and thermopower of polycrystalline Sr-doped LaCoO3 with composition La0.95Sr0.05CoO3. Our data show that the investigated compound exhibits a very respectable room-temperature thermoelectric figure of merit value of 0.18. Our results not only sho…
The effects of curvature on the structure, electronic and optical properties of isolated single-walled carbon nanotubes are studied within a symmetry-adapted non-orthogonal tight-binding model using 2s and 2p electrons of carbon. The symmetry-adapted scheme allows reducing the matrix eigenvalue problem for the electro…
Magnetron-sputter-deposited austenitic 330 stainless steel (330 SS) films, several microns thick, were found to have a hardness ∼6.5 GPa, about an order of magnitude higher than bulk 330 SS. High-resolution transmission electron microscopy revealed that sputtered 330 SS coatings are heavily twinned on {111} with nanom…
We demonstrate that the nanoscale assemblies of water-solubilized, oppositely charged CdSe/ZnS core/shell quantum dots and of quantum dots and nanogold particles make it possible to develop FRET-based sensors with a donor quenching efficiency close to 100%. The cw and time-resolved photoluminescence analysis of nanoas…
Electrospinning is a technique employed for preparing polymer fibers having diameters in the range of 10 μm–10 nm using high electrostatic field. In this letter, we report the formation of aligned polymer fibers, several centimeters in length, with separation between the fibers in the range of 5–100 μm. Achieving alig…
Thermoelectrics are devices that convert heat to electricity directly, or vice versa. To be technologically useful, thermoelectric materials with high efficiency must be found, along with better tools to understand them. In his Perspective, Majumdar discusses the reports by Hsu et al . and Lyeo et al . that tackle the…
The conversion of heat to electricity by thermoelectric devices may play a key role in the future for energy production and utilization. However, in order to meet that role, more efficient thermoelectric materials are needed that are suitable for high-temperature applications. We show that the material system AgPb(m)S…
Abstract A new homologous series of thermotropic liquid crystalline poly(hydrazone–ether)s based on the 1,3,4‐thiadiazole moiety in the main chain was synthesized by solution polycondensation of various diformyl‐α,ω‐diphenoxyalkanes with 2,5‐bis(mercaptoacetic hydrazide)‐1,3,4‐thiadiazole. The inherent viscosity of th…
Abstract A series of thio‐containing poly(ether ether ketone) (PEESK) polymers was synthesized by the introduction of thio groups from 4,4′ thiodiphenol (TDP) into the poly(ether ether ketone) (PEEK) structure via reaction between the phenol and aromatic fluoride groups. The effect of the thio groups on the properties…