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 18 of 18 for “"Collective mode"”.
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Controlling and probing nonlinear collective mode dynamics in quantum materials
… In particular, the excitation of low-energy collective modes in solids—such as lattice vibrations (phonons) and spin precessions (magnons)—to large amplitudes opens fundamentally new pathways for controlling and probing material properties that are otherwise inaccessible under thermal …
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Carrier momentum relaxation in highly doped polar semiconductors and semiconductor heterostructures
… industry. Most strikingly, transistors in modern electronic devices are polar semiconductor heterostructures. It is important to thoroughly understand carrier transport in such structures. In doped polar semiconductors, collective excitations of the carriers (plasmons) and the atoms (polar …
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Ultrafast terahertz spectroscopy and control of collective modes in semiconductors
… of semiconductor physics and in particular of collective mode excitations in semiconductors. We detect and analyze THz radiation emitted by these collective modes to reveal the underlying physics of many-body interactions. We review a design, implementation and characterization of our ultrafast …
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Aspects of Moiré Quantum Matter
… matter has newly unified disparate themes in modern condensed matter physics, chief among them band theory, correlations, and topology. This thesis investigates how the interplay between these foundational elements leads to novel electronic phenomena uniquely enabled by moiré superlattices. We …
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Charge fluctuations of the strange metal in space and time
… to Bi-2212 and a propagating Fermi liquid collective mode at low-energies and momentum. Upon cooling, low-energy spectral weight is suppressed in the strange metal continuum and the Fermi liquid collective mode velocity is strongly renormalized. These findings confirm the strange metal and …
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Fluctuation conductivity from charge density waves in pseudo-one-dimensional systems
… examines theoretically the Fröhlich conductivity model, which describes a charge-density-wave phenomenon which can lead to enhanced electrical conductivity in pseudo-one-dimensional systems. The experimental facts concerning pseudo-one-dimensional systems which may illustrate aspects of the …
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Evolution of the distribution of high energy nuclei and induced collective modes in plasmas
… single-particle effects and interactions with collective modes in the plasma will be considered. Part of this research will focus on the distribution of high energy nuclei undergoing motion in unperturbed orbits. This work utilizes appropriate symmetry properties and conservation laws, …
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Collective excitations in layered materials with momentum-resolved electron energy loss spectroscopy
… Lastly, the observation of a novel electronic collective mode in TiSe2 is presented as strong evidence for an excitonic insulator phase in this compound.
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Crystalline Protein Dynamics : A Simulation Analysis of Staphylococcal Nuclease
… functional protein dynamics and will improve models for refinement against diffraction data. In this thesis, molecular dynamics (MD) simulations of crystalline Staphylococcal nuclease are reported and analysed in terms of fluctuations, correlations, X-ray diffuse scattering, disorder and …
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Low-Energy Effective Field Theories for the Antiferromagnetic Quantum Critical Metal with Z2, O(2) and O(3) spin symmetries
… kinetic energy quenching as the speed of the collective mode (c) and the Fermi velocity perpendicular to the magnetic ordering vector (v) become vanishingly small at low energies. However, the low-energy physics of the Z2, O(2) and O(3) theories qualitatively differ from each other due to …
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Interference of Intensity Noise in a Multimode Nd:YAG Laser
… of the intensity noise in a multi-longitudinal mode Nd:YAG laser. This type of laser is a nonlinear system which exhibits complicated dynamics within the intensity noise. For example, antiphase dynamics is where there is cancellation of one or more collective modes of oscillation, which are …
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Collective modes in strongly correlated electron systems measured with momentum-resolved electron energy-loss spectroscopy
… about the bosonic emergent particles, or the collective modes, of a material. Momentum-resolved electron energy-loss spectroscopy (M-EELS) can measure χ(q,ω) of strongly correlated materials at the low energy scales of interest. The ability to measure the momentum-dependence of the collective …
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Topological phenomena in ultracold atomic gases
… semiclassical dynamics of a wavepacket and the collective modes of an ultracold gas. We also study theoretically the dynamics of skyrmion-antiskyrmion pairs in a Bose Einstein condensate. Firstly, we propose a general method by which experiments can map the Berry curvature across the Brillouin …
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From Spheres to Sheets: Colloidal Hydrodynamics, Thermodynamics, and Statistical Inference
… to aid in the simulation of large-scale physical models. Drawing on the Riemannian optimization and sequential quadratic programming literature, a practical algorithm that we call Locally Feasibly Projected Sequential Quadratic Programming (LFPSQP) is constructed to conduct feasible optimization …
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Laser-coupled scanning tunneling microscopy and spectroscopy of quantum materials and qubit defects
… transient bias voltages requiring significant modeling for interpretation of energy-resolved measurements. In this thesis, I describe the design and construction of a new laser-coupled scanning tunneling microscope which can simultaneously achieve sub-ps time resolution, sub-Å spatial …
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Hollow condensates, topological ladders and quasiperiodic chains
… physics of one-dimensional quasiperiodic models, and end by focusing on the physics of localized edge modes and topological phases in quasi-one-dimensional ladder models. For all three topics we maintain a focus on experimentally accessible, physically realistic systems and explicitly …
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Magnetodynamics of pseudo spin valves investigated using co-planar waveguide and spin torque ferromagnetic resonance techniques
… nonlinear localized and propagating spin wave modes for use in magnonics. In this thesis, we study some aspects of these structures from the fundamental physics point of view using the spin torque ferromagnetic resonance technique (ST-FMR) and conventional broadband FMR technique. The structure …
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AB-INITIO DYNAMICS IN STRONGLY INTERACTING MANY-BODY SYSTEMS
… many-body systems remains a key problem in modern physics due to the quantum correlations they develop, which result in highly nontrivial macroscopic phenomena which still defy our efforts of a thorough theoretical understanding, like quantum phase transitions, collective excitations, …