Electronic band structure

About: Electronic band structure is a research topic. Over the lifetime, 25997 publications have been published within this topic receiving 669557 citations. The topic is also known as: band structure.

Evolution of Electronic Structure in Atomically Thin Sheets of WS2 and WSe2

Abstract: Geometrical confinement effect in exfoliated sheets of layered materials leads to significant evolution of energy dispersion with decreasing layer thickness. Molybdenum disulphide (MoS2) was recently found to exhibit indirect to direct gap transition when the thickness is reduced to a single monolayer. This leads to remarkable enhancement in the photoluminescence efficiency, which opens up new opportunities for the optoelectronic applications of the material. Here we report differential reflectance and photoluminescence (PL) spectra of mono- to few-layer WS2 and WSe2 that indicate that the band structure of these materials undergoes similar indirect to direct transition when thinned to a single monolayer. Strong enhancement in PL quantum yield is observed for monoayer WS2 and WSe2 due to exciton recombination at the direct band edge. In contrast to natural MoS2 crystals extensively used in recent studies, few-layer WS2 and WSe2 show comparatively strong indirect gap emission along with distinct direct gap hot electron emission, suggesting high quality of synthetic crystals prepared by chemical vapor transport method. Fine absorption and emission features and their thickness dependence suggest strong effect of Se p-orbitals on the d electron band structure as well as interlayer coupling in WSe2.

Electron Correlation and Ferromagnetism of Transition Metals

Abstract: The electron correlation in a narrow energy band is discussed taking into account the multiple scattering between two electrons. The discussion is an adaptation of Brueckner's theory of nuclear matter. It is assumed that electrons interact with each other only when they are at the same atom. The effect of the electron correlation depends in an intricate way on the energy spectrum of a given band. An approximate expression of the effective magnitude of the interaction is derived. The condition for the occurrence of ferromagnetism is investigated for various types of bands. The ferromagnetism of Ni and the paramagnetism of Pd can be understood reasonably through the present approach. The degeneracy of the d bands is taken into account in the discussion of these metals. (auth)

Photonic band structure: The face-centered-cubic case employing nonspherical atoms.

Abstract: We introduce a practical, new, face-centered-cubic dielectric structure which simultaneously solves two of the outstanding problems in photonic band structure. In this new ``photonic crystal'' the atoms are nonspherical, lifting the degeneracy at the W point of the Brillouin zone, and permitting a full photonic band gap rather than a pseudogap. Furthermore, this fully three-dimensional fcc structure lends itself readily to microfabrication on the scale of optical wavelengths. It is created by simply drilling three sets of holes 35.26\ifmmode^\circ\else\textdegree\fi{} off vertical into the top surface of a solid slab or wafer, as can be done, for example, by chemical-beam-assisted ion etching.

Band Structure of Graphite

Abstract: Tight-binding calculations, using a two-dimensional model of the graphite lattice, lead to a point of contact of valence and conduction bands at the corner of the reduced Brillouin zone. A perturbation calculation which starts with wave functions of the two-dimensional lattice and is applied to the three-dimensional lattice is described. Some general features of the structure of the $\ensuremath{\pi}$ bands in the neighborhood of the zone edge are obtained and are expressed in terms of appropriate parameters.

Photoelectron spectroscopy : principles and applications

Abstract: 1. Introduction and Basic Principles.- 2. Core Levels and Final States.- 3. Charge-Excitation Final States: Satellites.- 4. Continuous Satellites and Plasmon Satellites: XPS Photoemission in Nearly Free Electron Systems.- 5. Valence Orbitals in Simple Molecules and Insulating Solids.- 6. Photoemission of Valence Electrons from Metallic Solids in the One-Electron Approximation.- 7. Band Structure and Angular-Resolved Photoelectron Spectra.- 8. Surface States, Surface Effects.- 9. Inverse Photoelectron Spectroscopy.- 10. Spin-Polarized Photoelectron Spectroscopy.- 11. Photoelectron Diffraction.- A.1 Table of Binding Energies.- A.2 Surface and Bulk Brillouin Zones of the Three Low-Index Faces of a Face-Centered Cubic (fcc) Crystal Face.- A.3 Compilation of Work Functions.- References.