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 25 for “"electron correlations"”.
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Semiconductor nanodevices as a probe of strong electron correlations
An electron is usually considered to have only one type of kinetic energy, but could it have more, for both its spin and charge, or by exciting other electrons? In one dimension (1D), the physics of interacting electrons is captured well at low energies by the linear Tomonaga- Luttinger Liquid …
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Wavefunction-based method for excited-state electron correlations in periodic systems - application to polymers
… is obtained with the correlation of all electrons in the system being included on a very high level of sophistication. The account of correlation effects leads to substantial shifts of the "center-of-mass" positions of the bands (valence bands are shifted upwards and conduction …
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A Correlated 1-D Monatomic Condensed Matter System: Experiment and Theory
… it may inherit due to quantum confinement and electron correlations. The experimentally realized system is a self-assembled array of monatomic cobalt wires that are grown under ultra-high vacuum conditions on a vicinal copper (111) substrate using a recipe developed specifically for this work. …
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Experimental consequences of mottness in high-temperature copper-oxide superconductors
… doped Mott insulators, the interaction between electrons is particularly strong. The strong electron correlations are responsible for the breakdown of Fermi-liquid behavior in the normal state. A variety of experimental probes reveal anomalous features in these materials. Such anomalies are …
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Rapid materials discovery of ternary transition metal chalcogenides
… metal chalcogenides exhibiting strong d-electron correlations. These materials result in a plethora of exotic physical phenomena such as superconductivity, metamagnetic metallic behavior, and quantum phase transitions via a complex interplay of spin, charge, lattice and orbitals degrees …
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Path integral Monte Carlo simulations and their relation to recent advances in nanophysics
… In the case of quantum dots, shell effects and electron correlations for up to 12 electrons are studied. Furthermore, the addition energies are qualitatively reproduced using PIMC. In nanoscopic quantum rings, a parameter dependent transition between a spin ordered and disordered Wigner crystal …
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Time Domain Spectroscopy of Graphene
… of photo-excited graphene. Graphene undergoes electronic band renormalization after photo exciting carriers. By measuring a differential transmission spectrum, small changes to the band structure can be quantified. I will explain how screened exchange and electron phonon self energies provide …
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Hofstadter Physics and Composite Fermionic Phase in Moiré Systems
This thesis explores the intricate electronic phenomena in Moiré systems, particularly focusing on twisted bilayer transition metal dichalcogenides (TMD). These systems, with their unique superlattice structures and strong electron correlations, provide fertile ground for investigating novel …
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Effects of a single magnetic impurity on superconductivity
Electronic structure of a conventional superconductor in the vicinity of a single, iso- lated magnetic impurity has been probed experimentally with scanning tunneling spectroscopy by Yazdani et al.. Motivated by their experiment, we study the ef- fects of a single magnetic impurity on …
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Studies in the electronic structure of matter
… take into account the difference in average electron-electron repulsion of initial and final states. The results are consistent with transition rates computed by other authors using a variety of many-electron techniques. It is suggested that wavefunctions determined in the manner described …
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First principles quantum Monte Carlo study of correlated electronic systems
The many-body correlation between electrons is the origin of many fascinating phenomena in condensed matter systems, such as high temperature superconductivity, superfluidity, fractional quantum Hall effect, and Mott insulator. Strongly correlated systems have been an important subject of condensed …
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Spin-Orbit Coupling in SrTiO3/Si Thin Films at High Carrier Concentration
… has recently demonstrated the co-existence of electron correlations and strong spin-orbit coupling on SrTiO3 films on Si(001). Our group has studied the sample having lower carrier concentration (≤ 10¹⁴, cmˉ²) which shows Weak- localization effect. As the carrier concentration increases ( (1 − …
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Search, Discovery, Synthesis and Characterization of Itinerant Magnets Composed of Non-magnetic Constituents
… local. Itinerant magnetism, caused by conduction electrons, has been of interest due to intriguing phenomena that frequently accompany it: heavy fermion behavior, coexistence of superconductivity and magnetism, metamagnetic transitions, spin- and cluster-glass behavior, multisublattice magnetism, …
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Non-classical methods for the simulation and design of quantum materials.
… semiconductor devices that drive modern electronics. Many of these materials can be studied and understood computationally through classical methods such as Density Functional Theory, which apply traditional first-principles simulations of material physics. However, the simulation of …
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Magnetotransport in superconductor to semiconductor junctions: multiple Andreev reflections and coupling to quantum hall states
Two-dimensional electron gases (2DEGs) and superconductors share many interesting properties. Both exhibit dissipationless current flow as well as strong electron correlations which can lead to a new ground state charge carrier. In this work, coupling between superconductors and 2DEGs was studied. …
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Ultrafast photoinduced dynamics of low-dimensional excitonic materials at room temperature
… for both passivating defects and tuning optoelectronic properties. We next turn our attention to the quasi-1D excitonic insulator candidate Ta₂NiSe₅. At 328 K, this material is proposed to undergo a spontaneous symmetry breaking, leading to the Bose-Einstein condensation of excitons in the …
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Insights into correlated electron systems from first-principles quantum Monte Carlo
… where it is important to properly account for electron correlations. I report several benchmarks establishing that variational Monte Carlo (VMC) and fixed-node diffusion Monte Carlo (FN-DMC) are efficient enough to compute properties of realistic systems while significantly improving on the …
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Synthetic Topological Quantum Matter in Nanostructured 2D Materials for Quantum Information Processing
… this thesis, we contribute to understanding the electronic properties of two-dimensional materials, with a strong emphasis on graphene-based nanostructures, such as twisted multilayer graphene and triangular graphene quantum dots. The thesis is organized into six chapters, including an …
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Growth of low disorder GaAs/AlGaAs heterostructures by molecular beam epitaxy for the study of correlated electron phases in two dimensions
… probing interaction effects in two-dimensional electron and hole gases. This dissertation presents work aimed at further understanding the key material-related issues currently limiting the quality of these 2D systems, particularly in relation to the fractional quantum Hall effect in the …
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