Materials Literature
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The accepted approximation used to describe quantum interference patterns at steps is shown to be incorrect. As a result, electron lifetimes determined using it are in error by a factor 2.
We show, by SQUID magnetometry, that in (Ga,Mn)As films the in-plane uniaxial magnetic easy axis is consistently associated with particular crystallographic directions and that it can be rotated from the [-110] direction to the [110] direction by low temperature annealing. We show that this behavior is hole-density-de…
A facile solution-phase process has been demonstrated for the selective preparation of single-crystalline bismuth nanowires and nanospheres by reducing sodium bismuthate with ethylene glycol in the presence of poly(vinyl pyrrolidone) (PVP) or acetone. Bismuth nanobelts and Bi/Bi(2)O(3) nanocables could be also obtaine…
We have measured temperature-dependent magnetic Compton profiles (MCPs) from a single crystal of La$_{1.2}$Sr$_{1.8}$Mn$_2$O$_7$. The MCPs, which involved the scattering of circularly polarized x-rays, are in general related to the momentum density of all the unpaired spins in the system. Nevertheless, we show that wh…
We have observed at low temperatures (<8K) hysteretic I(V) characteristics for sub-mkm (~200nm) metallic break-junctions based on the heavy-fermion compound UPd2Al3. Degrading the quality of the contacts by in situ increasing the local residual resistivity or temperature rise reduces the hysteresis. We demonstrate tha…
The analogy of the nonlinear dislocation theory in crystals and the electromagnetism theory is studied. The nature of some quantities is discussed.
The size effect of the raw B powder on the MgB2 phase formation has been studied by the technique of in-situ high temperature resistivity (HT-rT) measurement. The onset temperature, Tonset, and the completion temperature, TPF, of the phase formation are determined directly during the ongoing thermal process. These two…
A local and medium range atomic structure model for the face centred icosahedral (fci) Mg25Y11Zn64 alloy has been established in a sphere of r = 27 A. The model was refined by least squares techniques using the atomic pair distribution (PDF) function obtained from synchrotron powder diffraction. Three hierarchies of t…
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We report on the intershell electron transport in multiwalled carbon nanotubes (MWNTs). To do this, local and nonlocal four-point measurements are used to study the current path through the different shells of a MWNT. For short electrode separations $\ensuremath{\lesssim}1\text{ }\ensuremath{\mu}\mathrm{m}$ the curren…
Carbon nanotubes (CNTs), whether single- or multi-walled (SWNT or MWNT, respectively), have, in an unparalleled fashion, grabbed the attention of both researchers and business leaders within the polymer community. The vast potential afforded by the unprecedented combination of mechanical, electrical, and thermal prope…
The Ni ion in $\mathrm{La}\mathrm{Ni}{\mathrm{O}}_{2}$ has the same formal ionic configuration $3{d}^{9}$ as does Cu in isostructural $\mathrm{Ca}\mathrm{Cu}{\mathrm{O}}_{2}$, but it is reported to be nonmagnetic and probably metallic whereas $\mathrm{Ca}\mathrm{Cu}{\mathrm{O}}_{2}$ is a magnetic insulator. From ab in…
The controlled synthesis of Cu(OH) 2 nanowires and nanoribbons in a solution phase has been realized with high yield at low cost by simply dropping KOH and ammonia solutions into an aqueous solution of CuSO 4 at ambient temperature. It is demonstrated that the morphology of nanostructured Cu(OH) 2 is significantly inf…
Recent research on the incorporation of carbon nanotubes (CNTs) into ceramic and metal matrices to form composite structures is briefly reviewed, with an emphasis on processing methods, mechanical performance, and prospects for successful applications.
Clay/polymer nanocomposites offer tremendous improvement in a wide range of physical and engineering properties for polymers with low filler loading. This technology can now be applied commercially and has received great attention in recent years. The major development in this field has been carried out over the last…
Poly(dimethylsiloxane) [-Si(CH3)(2)O-] is by far the most studied of the polysiloxanes and is known to exhibit some intriguing physical properties, in particular very high permeability to gases. Simulations are underway in an attempt to understand some of these peculiarities. In addition, other symmetrically substitut…
Photochromic reactions of diarylethene derivatives were detected at a single-molecule level by using a fluorescence technique. Fluorescent photoswitching molecules in which photochromic diarylethene and fluorescent bis(phenylethynyl)anthracene units are linked through an adamantyl spacer were synthesized, and switchin…
Planar metamaterials that exhibit a zero index of refraction have been realized experimentally by several research groups. Their existence stimulated the present investigation, which details the properties of a passive, dispersive metamaterial that is matched to free space and has an index of refraction equal to zero.…
We describe monocrystalline graphitic films, which are a few atoms thick but are nonetheless stable under ambient conditions, metallic, and of remarkably high quality. The films are found to be a two-dimensional semimetal with a tiny overlap between valence and conductance bands, and they exhibit a strong ambipolar el…
It has been conjectured that atomic oxygen and ozone can have a great influence on the plasma oxidation of ultrathin aluminum for magnetic tunnel junctions. In order to measure the density of O and ozone, two-photon absorption laser induced fluorescence measurements are performed in the dc glow plasma that is used for…