Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
Results
Showing 1 to 20 of 36 for “"Brillouin zone"”.
-
Geometry and Topology of Quantum States in Quasicrystalline Systems
… by an effective band structure, albeit with the Brillouin zone replaced by a space referred to as a `pseudo' Brillouin zone. Within a corresponding semiclassical picture, we find the presence of Bloch oscillations, usually synonymous with periodicity, alongside additional anomalous terms due to …
-
Frequency-scale effect in elastic periodic muti-layered media
… media. This solution allows the definition of Brillouin zones whose width is equal to pi/d and shows that the periodic medium exhibits a range of stop-bands frequencies where the wave does not propagate. These stop-bands are located at the boundary of the Brillouin zone for the all of the types …
-
Photoemission studies of noble metal semiconductor systems
… and mapped along high-symmetry directions in the Brillouin zone for most of the clean substrates. The previous surfacestate assignments are rigorously confirmed. Quantitative structural details for these surfaces are deduced with the aid of core-level line shape analysis. The results agree with …
-
First principles Monte Carlo simulation of charge transport in semiconductors
… set of transitions throughout the entire Brillouin zone and over a wide range of energies, taking into account the details of each phonon mode. These matrix elements are then incorporated into a unique Monte Carlo charge transport simulator with which transport statistics are calculated. …
-
Extreme ultraviolet response of ionic crystals
… at approximately 50,000 points in the first Brillouin zone by a combined interpolation scheme utilizing the pseudopotentia1 method and the tight binding method of Slater and Koster. Available ESCA data was used to position the conduction band minimum with respect to the onset of absorption. …
-
Topological phenomena in ultracold atomic gases
… can map the Berry curvature across the Brillouin zone, and thereby determine the topological properties of the energy bands of optical lattices. The Berry curvature modifies the semiclassical dynamics and hence the trajectory of a wavepacket undergoing Bloch oscillations. Our general …
-
Intrinsically Localized Lattice Vibrations in Crystalline Lattices
… high-symmetry point L=▁q (π/a,π/a,π/a) of the Brillouin zone, the relative momentum vector ▁k remains invariant at ▁k (π/2,π/2,π/2) for a certain threshold value of ▁q, and coalesces at the upper-edge of the two-phonon density of states spectrum with high degeneracy in the two-phonon critical …
-
Fabrication and characterisation of bismuth nanowires
… of the direct band gap at the L-point of the Brillouin zone caused by quantum-size effects, or to a blueshift of the plasma frequency produced by surface defects acting as dopants. In addition, electrical resistance of single bismuth nanowires, embdedded in the template, has been measured as a …
-
Lattice dynamics of Chevrel phase compounds
… mm3 were grown. The energies and symmetries of Brillouin zone-center phonons of these crystals were measured by Raman spectroscopy. These energies are in good agreement with data reported in the literature obtained by measurements of superconducting tunnel junctions. The Raman data, extending …
-
Investigation of renormalization effects in high temperature cuprate superconductors
… spectra both in nodal and antinodal parts of the Brillouin zone. The smearing of the dip in the in the spectral line shape measured at (pi; 0) point can be well explained by coupling of electrons to the magnetic resonance mode. The effect of Zn and Ni substitution on the antinodal ARPES spectra …
-
Ultracold quantum gases in one-dimensional optical lattice potentials : nonlinear matter wave dynamics
… can be suppressed. By preparing a BEC at the Brillouin zone edge, we observed bright atomic gap solitons – non-spreading wave packets. They form, if the atom number and the lattice potential depth is tuned such that the effect of the repulsive atomic interaction and the anomalous dispersion …
-
Harmonic and Supercontinuum Generation in Zinc-Blende Materials
… into account contributions from the entire 3D Brillouin zone, and the connection between symmetry of the medium and the generation of high harmonics is illustrated.
-
Topics in the theory of semiconductors
… of Si, Ge, and GaAs at symmetry points in the Brillouin zone using a variational method within the local-density-functional formalism. The results are in good agreement with experimental values. The negative pressure derivatives of the gaps at the X point of the conduction band relative to the …
-
Electroreflectance of germanium
… structure occur over an extended region of the Brillouin zone, including the L-point. Structure was also observed near 3 eV and 4 eV but the large amount of lifetime broadening prevented any detailed quantitative analysis. The 4 eV structure, however, was characteristic of a single 3-D …
-
Study of phonon transmission through solid-solid interfaces and superlattices by phonon imaging
… phonon transmission due to gaps at the folded Brillouin zone boundary are observed for both longitudinal and fast transverse phonons. A newly predicted stopband within the zone due to coupling between the transverse and longitudinal acoustic modes is detected. The experimental results are …
-
Molecular dynamics investigation of the long wavelength dielectric response of classical dipolar liquids using Bloch function methods
… controlled, by a wavevector within the first Brillouin Zone, q, that is characteristic of the boundary conditions. In such cases, the accessible wavevectors are then all shifted by q, and so the minimum accessible wavevector is now q. A demonstration of how the Ewald summation is modified for …
-
Molecular dynamics calculation of mean square displacement in alkali metals and rare gas solids and comparison with lattice dynamics
… as in the molecular dynamics calculations. The Brillouin zone sums arising in the harmonic and the quartic terms were computed for very large numbers of points in q-space, and were extrapolated to obtain results ful converged with respect to the number of points in the Brillouin zone.An …
-
Raman scattering studies of spinels CoV2O4 and MnV2O4
… to strong magnon-phonon coupling at the Brillouin zone boundary. Our pressure-dependent studies of the one-magnon excitations reveal increased magnon damping with increasing pressure, which supports an increasing itinerant electronic character as the itinerant electron limit is approached …
-
Electroreflectance of gallium arsenide
… 'have a total effective area of .18 (l/a!) per Brillouin zone. In addition to these results lineshapes for flatband-to-accumulation modulations of the space charge electric field which may be due to band-filling at r, the low point of the conduction banels, have been observed. Finally, …
-
Angle resolved photoemission studies of silver bromide
… (111) single crystal from r to L in the first Brillouin zone which experimentally located the valence band maximum at L. Comparing the experimentally obtained band structure with speculative ones shows that the experimental ones are flatter than their speculative counterparts.
Page 1 of 2