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 24 for “"Electron-electron interaction"”.
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Strongly Correlated 2D Electronic Systems: Interplay between Band Topology and Electron-electron Interaction
… moiré materials. We found that band topology and electron-electron interaction can be easily tuned by electric field in these systems, which opens the door for various fascinating quantum many-body phenomena such as the quantum Hall effect at zero external magnetic field[3]. Our theoretical …
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Anisotropy effects in the critical field of superconducting tin-indium alloys
… energy gap is sensitive to the direction of the electron momentum relative to the crystal lattice - the so-called anisotropy effect. The reduction in electron mean free path which occurs upon addition of indium to pure tin reduces the effect of anisotropy in the electron-electron interaction. The …
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Polarizing agents for high-frequency Dynamic Nuclear Polarization : development and applications
… from polarization transfers from unpaired electrons, usually carried by a polarizing agent such as TEMPO (2,2,6,6-tetramethylpiperydin-l-oxyl), to the target nuclei. In this thesis, polarizing agents were developed for efficient polarization mechanisms at 5 Tesla. DNP using biradicals …
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Tddft Derivative Couplings And Other Topics In Quantum Chemistry
… which involve both the ground and excited electronic states of a molecule, can promote processes otherwise inaccessible by normal reactions. In general, photochemical reactions may be classified as adiabatic or nonadiabatic depending on whether the reaction takes place on the same adiabatic …
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Model for an exciton mechanism of superconductivity in planar geometry
… a model is developed in which the metal electrons with energies near the Fermi surface penetrate a short distance into the semiconductor. There they scatter by producing and absorbing virtual electron-hole pairs. The effect of such semiconductor polarization processes (i.e., the exciton …
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New methods of observation and characterization of fractional quantum Hall states
… (BLG). BLG is a novel material in which the electron-electron interaction can be tuned with the help of external parameters. This allows one to make one or another FQH state favourable. We develop a framework for theoretical investigation of the stability of FQH states in BLG. We apply our …
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Novel transport regimes in graphene
… due to a rich and complex interplay between electron-disorder, electron-electron, and electron-phonon interactions. Graphene, a newly discovered carbon one-atom-thick material, has unique transport characteristics, some of which are already well understood, whereas some are being under …
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Time resolved dynamics of charge density waves in solids : an uncorrelated and a correlated case
… charge modulation in a metal, induced by electron-phonon or electron-electron interaction, which breaks the translational symmetry of the underlying electron gas. The charge density wave order is ubiquitous among condensed matter systems, and its equilibrium properties have been well …
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One-dimensional bosonization approach to higher dimensions
… one-dimensional and quasi one-dimensional electron systems. The properties of one-dimensional electron systems can be studied within the bosonization technique, which presents fermions as collective bosonic density excitations. The power of this approach is the ability to treat …
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Dynamics of plasmon-induced hot carriers in metallic nanoparticles
… harvesting. Although many great features of hot electrons have been studied through previous works, the generation process and dynamics of them are still less understood. A more comprehensive theoretical model is needed to build the basic framework to predict and explain the behavior of hot …
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Holomorphic Hartree-Fock Theory: Moving Beyond the Coulson-Fischer Point
… pathways. Recently, nonorthogonal configuration interaction (NOCI) using a basis of multiple Hartree-Fock (HF) states has been proposed to predict electronic energies in this type of system. However, NOCI has previously been hindered by the disappearance of HF states as the molecular structure …
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Electronic and optical properties of thin-film superconductors and superconductor - semiconductor interfaces
… may also be used in future superconducting electronic device applications. Our studies of the interfaces between high-quality thin film Nb and NbN superconductors, and (100) n+-InAs (10^19cm^-3 ) are done by transport and optical measurements. For the first time, the proximity effect in …
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Tunneling spectroscopy of carbon nanostructures: a romance in many dimensions
… in carbon nanotubes, which shed light on electron – electron interaction in carbon nanotubes and low dimensional systems in general. We also apply those methods to two dimensional graphene sheets. We first review the fabrication techniques used to make the devices studied here. Some of the …
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Measurement of electron-electron interactions in one dimension with tunnelling spectroscopy
… of excitations born out of particle-particle interactions, which resemble the constituent single particles, albeit with renormalised mass. In one dimension, however, the formation of such a correlated state is unfavourable and the quasiparticles are completely absent. Instead, 1D fermions are …
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Ultrafast terahertz spectroscopy and control of collective modes in semiconductors
… to reveal the underlying physics of many-body interactions. We review a design, implementation and characterization of our ultrafast terahertz (THz) time-domain spectroscopy setup, with additional features of mid-infrared tunability and coherent as well as incoherent detection capabilities. …
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On the Dynamics of Single-Electron Tunneling in Semiconductor Quantum Dots under Microwave Radiation
… in this thesis to reveal the dynamics of single-electron tunneling and to realize quantum bits (qubits) in semiconductor quantum dots. At low temperatures, confined single quantum dots and double quantum dots are realized in the twodimensional electron gas (2DEG) of AlGaAs/GaAs heterostructures. …
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Photoionization of atoms with ultrashort XUV laser pulses at extreme intensities
… intense and ultrashort XUV-laser pulses of free-electron lasers. In particular, the influence of coherent dynamics of the electrons as well as the electron-electron interaction are in focus of this survey and the resulting signatures as Rabi oscillations and characteristic spectra of …
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Theoretical Modeling Of Electron Transport In Molecular Devices
Modern electronics technology has reached a very sophisticated stage. Requirements for smaller and reliable devices are becoming more and more demanding. It is predicted that Moore's law in making a faster CPU is going to break down in the foreseeable future. People start to look into new materials …
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Low-dimensional electron transport and surface acoustic waves in GaAs and ZnO heterostructures
… also in quantum physics research, such as nanoelectronics, spintronics, quantum optics, and even quantum information processing. Here, I focus on low-dimensional electron transport and SAWs in GaAs and ZnO semiconductor heterostructures. The ability to pattern quantum nanostructures using gates …
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Metallic Ground State of Functionalized Carbon Nanotubes
… effects. In classical three-dimensional metals, electron-electron interaction mainly leads to a renormalization of the charge carrier properties (e.g. effective mass), as described in Landau's Fermi liquid theory. One-dimensional metals are influenced to a greater extent by interactions. In fact, …
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