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.
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Showing 1 to 20 of 28 for “"many-body effects"”.
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Many-Body Effects on the X-Ray Spectra of Metals
The effects of band structure, of a solid surface, of temperature, and of disorder on the many-electron X-ray spectra of metals are evaluated in a change-of-mean-field approximation using a one-dimensional nearest-neighbor tight-binding model of a metal.
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Many-body effects in metals, modulation doped quantum wells and doped semiconductors
… problem of X-ray edge singularities and peaks of many-body origin observed in the optical spectra is presented. We first establish the analogy between a system of one hole interacting with many electrons and the polaron, where one electron interacts with many phonons. We approach both cases as an …
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Angle-Resolved Photoemission Studies on the Many-Body Effects of High-Temperature Superconductor: Bi-2212
Spin fluctuations are defined as dynamic variations of spin density in both space and time. They are widely considered to play a essential role in the pairing mechanism of high temperature superconductors. Unconventional superconductors such as cuprates are believed to exhibit …
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Angle-Resolved Photoelectron Spectroscopy Studies of the Many-Body Effects in the Electronic Structure of High-Tc Cuprates
… of unconventional superconductivity, after many years of research the scientific community possesses a considerable store of theoretical knowledge about the problem. Over time, the focus is gradually shifted from finding a theoretical description of an experimentally observed phenomenon to …
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Many-body effects in the thermodynamic properites of Fermi liquids and the electron-phonon system and in the excitation spectrum of liquid 4HE
In this thesis I study two separate topics in many-body physics. In the first part I consider many-body effects in the thermodynamic properties of Fermi liquids and of the electron-phonon system. Using normal liquid 3He as an example, I show that the T3lnT corrections due to spin fluctuations …
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Many-Body Effects in the Thermodynamic Properties of Fermi Liquids and the Electron-Phonon System and in the Excitation Spectrum of Liquid Helium-4
In this thesis I study two separate topics in many-body physics. In the first part I consider many-body effects in the thermodynamic properties of Fermi liquids and of the electron-phonon system. Using normal liquid ('3)He as an example, I show that the T('3)lnT corrections due to spin fluctuations …
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Core-valence-valence auger spectra of the simple metals
… of these line shapes are performed with a static many-body model which treats the (static) screening of a core hole by conduction electrons with a phenomenological potential. Our model is applicable only to the simple metals, because free-electron theory is used to describe the conduction …
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Optical properties of two-dimensional transition metal dichalcogenides
… and high-performance nanophotonics. Many body effects are of great significance in 2-dimensional TMDs, especially when thinned down to a monolayer. As a result, the exciton-related phenomena are prominent in TMD monolayers, which distinguish the monolayers significantly from their …
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Charge Transport Physics of Organic Semiconductors at High Carrier Densities
… transport is highly correlated because of the many-body charge-charge and charge-ion interactions. This thesis focuses on the physics of organic semiconductors at such high carrier densities. Our understanding is mainly guided by charge transport studies, for instance the evolution of …
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Theory of terahertz intervalence band polaritons and antipolaritons.
… susceptibility evaluated with Non Equilibrium Many Body Green's Functions (NEGF), which is then adjusted to a Lorentzian fit. Finally, the resulting expression is included in the wave equation describing the propagating electric field in the medium. This model is applied to …
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Tunable spin polarization and conductance anomalies in mesoscopic one-dimensional systems
… transport in quasi-1D systems, accounting for many-body effects and neglecting spin–orbit couplings. Then, with this model, we predict that 1D systems can sustain a hierarchy of spin-polarized configurations which emerge above a carrier concentration threshold and are responsible for the 0.7 …
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CNT-reinforced polymer nanocomposite by molecular dynamics simulations
… are not pairwise additive and characterize the many body effects. We also quantify how these short-range perturbations of the polymer structure affect their local mechanical response and that of the composite as a whole. We find the local stiff of the polymer near the CNTs is 30 times higher …
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Theoretical characterisation of spheroidal PbSe/PbS Core/Shell colloidal quantum dot heterostructures
… properties of NQDs are well understood, the effects of NQD shape are less so. This thesis investigates the effect of ellipticity on the optoelectronic properties associated with spheroidal NQDs. To this end, a four-band, anisotropic, and radially variant k · p system Hamiltonian is expanded …
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Electroreflectance of germanium
… M critical point theory. In addition, effects due to band-filling were observed when the energy bands were bent into accumulation. These results indicate that the transitions responsible for this structure occur over an extended region of the Brillouin zone, including the L-point. …
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Investigation of renormalization effects in high temperature cuprate superconductors
… of the two-dimensional BZ, the renormalization effects are represented by an unusual band dispersion that develops a so-called ‘‘kink’’. In the vicinity of the (pi, 0) point of the BZ, where the order parameter reaches its maximum, the renormalization is noticeably stronger and makes itself …
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Two-Photon Quantum Interference Polarization Spectroscopy: Measurements of Transition Matrix Elements in Atomic Rubidium
… with emphasis on different, in nature, effects. This situation is typical for atomic physics in general.</p> <p>The purpose of present study is obtaining the experimental data on the radiative properties of atomic rubidium with precision considerably higher than that of the traditional …
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Ultrafast Charge and Energy transfer Dynamics in Organic-Transition Metal Dichalcogenides Heterostructures
… and its complex spectral evolution arising from many body effects at both the electronic and optical gap as a function of fluence were extracted and studied. These key properties are crucial to the potential application of TMD in optoelectronic devices. Afterwards the ultrafast energy, charge …
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