Materials Literature
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A complete mapping in the Brillouin zone of the structural instability associated with the ferroelectric phase transitions of ${\mathrm{KNbO}}_{3}$ has been obtained by first-principles calculations using a linear response approach. The wave-vector dependence of the instability reveals pronounced two-dimensional chara…
The oxidation of sputtering deposited copper thin films has been investigated. Phase identification and surface morphology characterization were performed by x-ray diffraction, Raman spectroscopy, and atomic force microscopy (AFM). The copper film is first oxidized to Cu2O below 300 °C and then to CuO at higher temper…
Experimental and theoretical graphite valence-band photoelectron angular distributions are presented and compared. We observe a zone-selection effect, wherein interference between photoelectron amplitudes from the two atoms in each graphene unit cell cause both \ensuremath{\sigma} and \ensuremath{\pi} states to appear…
The response of an infinite, periodic, insulating solid to an infinitesimally small electric field is investigated in the framework of density functional theory. We find that the applied perturbing potential is not a unique functional of the periodic density change; it depends also on the change in the macroscopic pol…
The electronic structure of ${\mathrm{La}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$${\mathrm{Sr}}_{\mathit{x}}$${\mathrm{MnO}}_{3}$ has been studied by photoemission and O 1s x-ray-absorption spectroscopy. Spectra of the Mn 2p core levels and the valence bands for ${\mathrm{LaMnO}}_{3}$ and ${\mathrm{SrMnO}}_{3}$ have be…
Using the self-consistent orthogonalized linear-combination-of-atomic-orbitals method in the local-density approximation, the electronic structure and the optical properties of three phases of titanium dioxide have been studied. For rutile, the calculated band structure, equilibrium lattice constant, and bulk modulus…
Insulator-metal phenomena depending on band filling (doping degree), temperature, and external magnetic field have been investigated for prototypical double-exchange ferromagnets, namely, crystals of ${\mathrm{La}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$${\mathrm{Sr}}_{\mathit{x}}$${\mathrm{MnO}}_{3}$ (0\ensuremath{\le}…
Technical developments in the past few decades have led to scanners with greater accuracy and higher frequencies of operation at larger scan angles with wider apertures. The causes of this evolution of galvanometric and resonant scanners, whose attributes make sophisticated applications possible, are given in order to…
Fabrication issues of microlens arrays, made by first forming photoresist microlenses, by patterning and reflowing photoresist islands under temperature, and then transferring this into the substrate by a dry etch process, were studied. Photoresist microlenses were reliably fabricated within a range of aspect ratios.…
Linearized augmented plane wave (LAPW) calculations are performed for periodic (001) and (111) slabs of BaTiO$_3$ to understand the effects of surfaces on ferroelectric BaTiO$_3$. The (111) slab is found to be much less stable than the (001) slab. The average surface energies are respectively 3700 erg/cm$^2$ and 1600…
Motivated by recent experiments by Yuse and Sano (Nature, 362, 329 (1993)), we propose a discrete model of linear springs for studying fracture in thin and elastically isotropic brittle films. The method enables us to draw a map of the stresses in the material. Cracks generated by the model, imposing a moving thermal…
I present an informal discussion of various cases where two-dimensional surface metal-insulator structural and charge-density-wave instabilities driven by partly filled surface states have been advocated. These include reconstructions of clean semiconductor surfaces and of W(100) and Mo(100), as well as anomalies on t…
Carbon nanotube material can now be produced in macroscopic quantities. However, the raw material has a disordered structure, which restricts investigations of both the properties and applications of the nanotubes. A method has been developed to produce thin films of aligned carbon nanotubes. The tubes can be aligned…
The full set of high-energy spectroscopy measurements including X-ray photoelectron valence band spectra and soft X-ray emission valence band spectra of both components of FeSi (Fe K_beta_5, Fe L_alpha, Si K_beta_1,3 and Si L_2,3) are performed and compared with the results of ab-initio band structure calculations usi…
It has been shown previously that the magnetic field outside a spherically symmetric conducting body due to internal current sources does not depend on the profile of conductivity along the radius. It is demonstrated here that an arbitrary distribution of radial anisotropy superimposed on the symmetric conductivity, e…
Surface freezing is discovered in normal alcohol melts and studied using surface X-ray scattering techniques. A single crystalline bilayer is formed on the surface, at temperatures up to 1 °C above the bulk freezing temperature. The single bilayer persists down to bulk freezing. It is hexagonally packed, and the molec…
Diffraction characteristics of high-spatial-frequency (HSF) gratings are evaluated for application to polarization-selective computer-generated holograms by the use of two different approaches: second-order effective-medium theory (EMT) and rigorous coupled-wave analysis (RCWA). The reflectivities and the phase differ…
The properties of guided-mode resonance reflection filters constructed with multiple thin-film layers are addressed. Greatly improved filter characteristics are shown to follow by the incorporation of multiple homogeneous layers with the spatially modulated layer. Calculated results for single-layer, double-layer, and…
The harmonic diffractive lens is a diffractive imaging lens for which the optical path-length transition between adjacent facets is an integer multiple m of the design wavelength λ(o). The total lens thickness in air is mλ(o)/(n - 1), which is m times thicker than the so-called modulo 2π diffractive lens. Lenses const…
Diffractive lenses have been traditionally designed with the first diffracted order. The spectral characteristics of diffractive lenses operating in higher diffracted orders differ significantly from the first-order case. Multiorder diffractive lenses offer a new degree of freedom in the design of broadband and multis…