Materials Literature
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Abstract Since the arrival of the transistor in 1947, research in hot electrons, like any field in semiconductor research, has grown at a stunning rate. From a physicist's point of view the understanding of hot electrons and their interactions with the lattice has always been a challenging problem of condensed matter…
We emphasize the importance of choosing an appropriate correlation function to reduce numerical errors in calculating the linear-response function as a Fourier transformation of a time-dependent correlation function. As an example we take dielectric functions of silicon crystal calculated with a time-dependent method…
The mean-field theory for lossy nonlinear composites, described by complex and field-dependent dielectric functions, is presented. By using the spectral representation of linear composites with identical microstructure, we develop self-consistent equations for the effective response. We examine two types of microstruc…
We review recent results on the linear and non-linear optical response of realistic quantum-wire structures. Our theoretical approach is based on a set of generalized semiconductor Bloch equations, and allows a full three-dimensional multisubband description of Coulomb correlation for any shape of the confinement prof…
A model for high temperature superconductors based on the idea of Cooper pairs comprised of electrons from different bands is studied. We propose that the two bands relevant for the cuprates are comprised of Cu dx2-y2, dz2, planar O psigma, and apical O pz orbitals. Along the diagonal, kx=ky in the Brillouin zone, the…
A review of coherent phenomena in photoexcited semiconductors is presented. In particular, two classes of phenomena are considered: On the one hand the role played by optically-induced phase coherence in the ultrafast spectroscopy of semiconductors; On the other hand the Coulomb-induced effects on the coherent optical…
In this note we re-examine the classic Janssen theory for stresses in bins, including a randomness in the friction coefficient. The Janssen analysis relies on assumptions not met in practice; for this reason, we numerically solve the PDEs expressing balance of momentum in a bin, again including randomness in friction.
We present the results of a new Hubbard model for optimally doped LaSrCuO. This model uses parameters derived from BLYP calculations on the cluster CuO6. It explicitly includes the Cu dx2-y2 and dz2 orbitals, the O psigma orbitals, and the apical O pz orbitals. When correlation is properly included in the Hubbard mode…
The theoretical analysis of the ultrafast energy relaxation and transport phenomena in semiconductor superlattices is reviewed. In particular, we discuss the two equivalent quantum-mechanical pictures of Bloch oscillations and Wannier-Stark localization. A review of simulated experiments and their comparison with avai…
Epitaxial strain energies of epitaxial films and bulk superlattices are studied via first-principles total energy calculations using the local-density approximation. Anharmonic effects due to large lattice mismatch, beyond the reach of the harmonic elasticity theory, are found to be very important in Cu/Au (lattice mi…
We study the excitation of harmonic waves in thin elastic samples by a single dislocation in arbitrary motion. We consider both screw and edge dislocations that move perpendicularly to the surfaces of the layer. In Fourier space the displacement velocity and dynamic stress fields generated by the motion of the disloca…
The broadband light scattering spectra of propylene glycol were studied by using a Sandercook-type 3 + 3-pass tandem Fabry - Pérot interferometer and a triple-grating spectrometer. The depolarized spectrum in the liquid phase at 363 K clearly shows an peak and a boson peak, and the former peak becomes lower remarkably…
Electrically conducting LaNiO3 (LNO) thin layers were deposited on (100)SrTiO3 (STO) and (100)LaAlO3 (LAO) substrates and crystallized at temperatures between 700 and 800 °C. The chemical method of deposition was solution sol-gel processing. X-ray 2θ and rocking curve measurements, φ scans, and atomic force microscopy…
We demonstrate a technique for experimentally determining stresses in crystalline thin films without any knowledge of the elastic properties of the thin film material. The results are obtained from interplanar spacing versus sin2 Ψ plots for different stress states. The interplanar spacings are measured by non-symmetr…
Atomic force microscopy (AFM) has been used to modify a polyimide surface to give controlled liquid crystal (LC) alignment, and to examine the modification produced. Strong LC azimuthal anchoring was observed typically for normal forces >300 nN and line densities >5 μm−1, and optically diffracting LC ele…
Deep metallic surface relief diffraction gratings are shown to couple radiation to surface plasmon polaritons when transverse magnetic radiation is incident in a plane orthogonal to the grating wave vector. This sharp resonance for a deep sinusoidal surface profile is explored using modeling programs and its presence…
Single crystals of lead magnesium niobate, ${\mathrm{PbMg}}_{1/3}{\mathrm{Nb}}_{2/3}{\mathrm{O}}_{3}$, were studied with x-ray scattering measurements at temperatures between 10 and 350 K. The diffuse scattering around odd-integer Bragg reflections ( $H+K+L\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}\mathrm{odd…
Erbium-doped multicomponent phosphate glass waveguides were deposited by rf sputtering techniques. The Er concentration was 5.3×1020 cm−3. By pumping the waveguide at 980 nm with a power of ∼21 mW, a net optical gain of 4.1 dB at 1.535 μm was achieved. This high gain per unit length at low pump power could be achieved…
We show that the magnetoelastic coupling between the magnetization and the amplitude of a short wavelength phonon enables the existence of a first order premartensitic transition from a bcc to a micromodulated phase in ${\mathrm{Ni}}_{2}\mathrm{MnGa}$. Such a magnetoelastic coupling has been experimentally evidenced b…
We calculate the linear magneto-optical Kerr rotation for CeSb in the near-infrared spectral range. Using an exact formula for large Kerr rotation angles and a simplified electronic structure of CeSb we find at \hbar ω= 0.46 eV a Kerr rotation of 90 degree which then for decreasing ωjumps to -90 degree as recently obs…