Condensed Matter Physics Commons^™

Exciton Dynamics, Interaction, And Transport In Monolayers Of Transition Metal Dichalcogenides, Saroj Chand

Dissertations, Theses, and Capstone Projects

Monolayers Transition metal dichalcogenides (TMDs) have attracted much attention in recent years due to their promising optical and electronic properties for applications in optoelectronic devices. The rich multivalley band structure and sizable spin-orbit coupling in monolayer TMDs result in several optically bright and dark excitonic states with different spin and valley configurations. In the proposed works, we have developed experimental techniques and theoretical models to study the dynamics, interactions, and transport of both dark and bright excitons.

In W-based monolayers of TMDs, the momentum dark exciton cannot typically recombine optically, but they represent the lowest excitonic state of the system …

Young Professionals: Fireside Chat With Jacques Lewiner And J. Keith Nelson At The Ieee Conference On Electrical Insulation And Dielectric Phenomena, Mattewos Tefferi, Allen Andersen, Sneha Hedge, Moein Borghei

Journal Articles

At the IEEE Conference on Electrical Insulation and Dielectric Phenomena (CEIDP), the Dielectrics and Electrical Insulation Society’s Young Professionals (DEIS-YP) Committee has initiated a YP luncheon event. This event aims to feature keynote speakers who share insights into their career trajectories with young professionals. In the current CEIDP edition, we had the privilege of hosting two distinguished speakers: Jacques Lewiner, the 2023 Whitehead Memorial Lecturer, and J. Keith Nelson, the 2022 recipient of the Dakin Award who also presented his award lecture at the CEIDP 2023. The fire- side chat was moderated by Allen Andersen, who began with initial questions …

Exploring The Physical, Structural, Optical, And Gamma Radiation Shielding Properties Of Borate Glasses Incorporating Sb2o3/Moo3, Elsayed Salama, Hesham A. Yousef, Ahmed E. Hannora, Y. Assran

Basic Science Engineering

The 10 Na2O-(30-x) MoO3- 60H3BO3-xSb2O3 glass system was prepared using the melt-quenching technique, where 30 ≥ x ≥ 10 mol%. X-ray diffraction and Fourier transform infrared spectroscopy were used to investigate the amorphous nature of the glass structure and the impacts of MoO3 and Sb2O3. As the antimony trioxide (Sb2O3) concentration increases at the expense of molybdenum trioxide (MoO3), the density and molar volume increase, and the optical bandgap energy and refractive index also increase. The radiation shielding characteristics were measured using a NaI(Tl) scintillation detector and calculated using the Phy-X/PSD platform. The increase in Sb2O3 concentration increases the values …

Epr Study Of Irradiated Starch: Induced Radicals And Dose Assessment, Elsayed Salama, Ahmed M. Maghraby, Samy A. Anwer, M. El-Sayed

Basic Science Engineering

Irradiation of starch is of much importance to get rid of microbes and for disinfection. EPR study of the ionizing radiation-induced radicals can lead to the assessment of radiation doses delivered during irradiation. The EPR spectra properties, microwave power saturation behavior, short- and long-term temporal dependencies, and other significant factors are studied. Response of EPR spectra of irradiated starch over the range (0.5–10 kGy) was investigated. The time dependence study of the radiation-induced signal radicals of starch showed that variation of the EPR signal can be noticed within ±7.7% relative to the average value over 38 days following irradiation. Results …

Doubly Rotating Coordinates: Wave Functions In Magnetic Resonance Problems, Sunghyun Kim

Graduate Thesis and Dissertation 2023-2024

The nuclear spin response to a rotating field H has been theoretically investigated from the 1930s to the 1950s. Building upon Majorana's probability theory, the behavior of spin 1/2 is well-illustrated in the joint review by Rabi, Ramsey, andSchwinger, and their spin wave function ψ is succinctly restated by Gottfried: ψ(t) = e^-iI_zωt/ℏe^{-i[I_z(ω₀-ω)+I_xω₁]t/ℏ}ψ(0).

However, the complexity involved in evaluating the wave function ψ in terms of probability amplitudes C_m attributed to the noncommutative nature of spin operators [I_x, I …

Outpatient Fall Prevention In Ambulatory Adults 65 Years Old And Over, Dorothy L. Osborne-White

Doctor of Nursing Practice (DNP) Scholarly Projects - Archive

Background: In the United States (U.S.), falls are the leading cause of injury among adults 65 and over, resulting in 36 million falls yearly (Moreland et al., 2020). According to the Centers for Disease Control and Prevention (CDC, 2023), one in four older adults experiences a fall each year. Falls are the world's second most prominent cause of accidental deaths (World Health Organization [WHO], 2021). Falls are the leading cause of both fatal and non-fatal injuries among older adults (Moreland et al., 2020).

Methods: A quality improvement project that included a fall bundle was implemented in a primary clinic. A …

Effect Of Annealing On Photoluminescence From Defects In Gan, Oleksandr Andrieiev

Theses and Dissertations

Annealing is a critical process in modern GaN technology, essential for achieving p-type conductivity by activating the Mg_Ga acceptor, as first demonstrated by Shuji Nakamura in the early 1990s. Despite the omnipresence of hydrogen as an impurity in GaN crystals, the precise mechanisms governing hydrogen diffusion and acceptor passivation remain only partially understood. The presented research investigates the effects of annealing-induced activation and hydrogen passivation on C and Be acceptors in GaN grown by MOCVD, HVPE, and MBE methods. We explored these effects by using several annealing techniques, gas compositions, and thermal regimes. A transient behavior between the C …

Investigation Of Charge Density Waves And Layer Stacking In Niobium Ditelluride, Gavin J. Smith

Honors Theses and Capstones

NbTe₂ is a layered transition metal dichalcogenide which exhibits charge density waves (CDWs) and superconductivity in the bulk. Previous scanning tunneling microscopy and spectroscopy experiments suggested that Fermi-surface nesting and reciprocal lattice reconstruction are important in the formation of CDWs in NbTe₂. These experiments focused on spectroscopy of pristine regions. We will present low temperature scanning tunneling spectroscopy experiments examining the 3x1 CDW in NbTe₂ at 10K. We found a crystalline step and multiple neighboring 60º and 120º CDW domain boundaries. We examined the electronic structure across these domain boundaries and in neighboring domains using scanning …

Synthesis And Characterization Of Quantum Materials, Yunsheng Qiu

Doctoral Dissertations

"In this study, attempts were made to grow quantum materials that have recently undergone a profound change of perspective. These materials are involved in intricate macroscopic properties rooted in the subtle nature of quantum physics. To explore our understanding of quantum materials, this study includes three projects: Magnetic Topological Insulators, Topological Superconductors, and high-temperature superconductors.

A Cr-doped Sb₂Te₃ is added to the category for the magnetic topological insulators project. Their transport properties are studied, and the origin of ferromagnetism is studied. Anomalous Hall effect is observed in the Hall measurements, and serval factors (cooling rate, dopant deficiency) …

Driven Magnetic Vortex Dynamics, Chase Hickman

Honors College Theses

Magnetic materials possess properties that allow for efficient data storage and transmission. Two important magnetic phenomena are domains and spin waves, both of which are active areas of research. Domains are regions of locally aligned magnetic moments within a material and spin waves are propagating disturbances in the alignment of those moments. A specific type of domain occurs when moments align to form a topological structure known as a magnetic vortex. Vortices are composed of a swirling in-plane magnetization centered around a localized region of out-of-plane magnetization known as a vortex core. A vortex has an in-plane chirality and out-of-plane …

A Closer Look At The Fabrication Of Some Doped Metal Ions In Borophosphate Glass System And Their Structural, Elastic, Optical, And Gamma-Ray Shielding Characteristics, Elsayed Salama, W. M. Abd-Allah, S. Marzouk, M. S. Gaafar

Basic Science Engineering

Borophosphate host glasses doped with zinc oxide (ZnO), titanium dioxide (TiO2), tellurium dioxide (TeO2), or cerium oxide (CeO2) were synthesized using rapid quenching techniques. Fourier transform infrared (FTIR) spectra, along with deconvoluted FTIR spectra, were recorded in the 400–4000 cm􀀀 1 range. Using the models of Tauc and Urbach, the optical energy band gaps of these glasses were found to be 3.212, 3.289, 3.262, 3.087, and 2.475 eV respectively. Due to the incorporation of different metal ions into the prepared glasses, the density increased and the molar volume decreased, making the glass structure highly compact. Since the elastic moduli are …

Complexity, Entanglement And Codes In Quantum Field Theory, Nikolaos Angelinos

Theses and Dissertations--Physics and Astronomy

In recent decades many deep connections between quantum information theory and quantum field theory have been unearthed. In this dissertation we study topics in high-energy physics through the lens of quantum information: 1) We develop connections between error-correcting codes and Narain conformal field theories. 2) We study the entanglement entropy of one-dimensional fermionic chains with long-range interactions. 3) We study the temperature dependence of Lanczos coefficients and Krylov complexity.

Topics In Quantum Information, Complexity And Chaos, Debarghya Chakraborty

Theses and Dissertations--Physics and Astronomy

This dissertation explores quantum information, the use of codes to describe quantum field theories, and introduces new concepts to characterize the dynamics of quantum many-body systems. The contributions of this dissertation are the following: 1) We constructed Narain Conformal Field Theories (CFTs) using additive codes, where the modular bootstrap constraints translate into algebraic conditions on the codes, extending previous approaches. This helps express key CFT data, including the torus partition function, in terms of codewords. We constructed optimal Narain CFTs for small central charges, and described CFT ensembles for asymptotically large central charge with large spectral gap. 2) We studied …

Dynamic Exchange-Correlation Functional For Bandgap Optimization: Reparametrization And Machine Learning, Viviana Faride Dovale Farelo

Graduate Theses, Dissertations, and Problem Reports (ETD)

This dissertation explores predicting the physical properties of solids using first-principles methods, with a focus on Density Functional Theory (DFT). DFT uses the electronic density within a material to predict its properties, simplifying the treatment of electron-electron interactions and allowing the study of realistic systems with a balanced treatment between accuracy and computational efficiency. Additionally, machine learning (ML) is employed to create correlations between some physical properties of solids and other properties or parameters that are more difficult to calculate.

The main problem addressed in this study is adjusting the parameters in the Strongly Constrained and Appropriately Normed (SCAN) semilocal …

Structural And Magnetic Properties Of Molecular Beam Epitaxy (Mnsb2te4)X(Sb2te3)1−X Topological Materials With Exceedingly High Curie Temperature, Candice R. Forrester, Christophe Testelin, Kaushini Wickramasinghe, Ido Levy, Dominique Demaille, David Hrabovsky, Xiaxin Ding, Lisa Krusin-Elbaum, Gustavo Lopez, Maria C. Tamargo

Publications and Research

Tuning the properties of magnetic topological materials is of interest to realize exotic physical phenomena, new quantum phases and quasiparticles, and topological spintronic devices. However, current topological materials exhibit Curie temperature (T_C) values far below those needed for practical applications. In recent years, significant progress has been made to control and optimize T_C, particularly through defect-engineering of these structures. Most recently, we reported T_C values up to 80 K for (MnSb₂Te₄)_x(Sb₂Te₃)_1−x when 0.7 ≤ x ≤ 0.85 by controlling the composition x and the …

Interpreting Neural Operators: How Nonlinear Waves Propagate In Non-Reciprocal Solids, Jonathan Colen, Alexis Poncet, Denis Bartolo, Vincenzo Vitelli

Data Science Faculty Publications

We present a data-driven pipeline for model building that combines interpretable machine learning, hydrodynamic theories, and microscopic models. The goal is to uncover the underlying processes governing nonlinear dynamics experiments. We exemplify our method with data from microfluidic experiments where crystals of streaming droplets support the propagation of nonlinear waves absent in passive crystals. By combining physics-inspired neural networks, known as neural operators, with symbolic regression tools, we generate the solution, as well as the mathematical form, of a nonlinear dynamical system that accurately models the experimental data. Finally, we interpret this continuum model from fundamental physics principles. Informed by …

Processing, Stability, And High-Temperature Properties Of Doped Lacro3-Based Refractory Ceramics And Composites For Harsh Environments Sensing Applications, Javier A. Mena

Graduate Theses, Dissertations, and Problem Reports (ETD)

In order to test and monitor the operational stability and conditions of various energy, transportation, and manufacturing systems and their components, accurate sensors capable of operating at temperatures over 1000 °C in various environments for long durations are required. In addition, many of these harsh environmental systems do not permit sensors to be directly inserted into the environment, so the sensors need to be embedded into the surrounding support or thermal protective materials. Some technological and industrial applications that require the use of harsh environment conditions sensing include nuclear and chemical reactors, jet engines, heavyduty gas turbines, rotating bearings in …

Mechanisms Of Dendritic Shorting In Lithium Metal Batteries With Li7la3zr2o12 Solid Electrolytes, Lukas Karapin-Springorum

Pomona Senior Theses

Energy storage will play a crucial role in efforts to mitigate the effects of climate change caused by greenhouse gas emissions from human activity. Lithium metal batteries using solid electrolytes like Li₇La₃Zr₂O₁₂ have higher energy density than lithium-ion batteries, which may enable a more rapid and complete electrification of transportation. However, lithium metal batteries suffer from undesirable short-circuiting when metallic lithium deposits connect the two electrodes. It has been debated whether these lithium dendrites generally grow directionally from the anode or are generated by the reduction of lithium ions inside the solid electrolyte, …

“Zero” Porosity High Loading Nmc622 Positive Electrodes For Li-Ion Batteries, Haidar Y. Alolaywi, Kubra Uzun, Yang-Tse Cheng

Chemical and Materials Engineering Faculty Publications

LiNi0.6 Mn0.2Co0.2 O 2 (NMC622) is a widely used positive electrode material for lithium-ion batteries, including electric vehicles. In this work, we investigated the effects of porosity, ranging from “zero” to the typical 35%, on the electrochemical behavior of high- loading NMC622 electrodes. Although it is well known that the energy density of the electrode increases with increasing areal capacity and decreasing porosity, NMC-positive electrodes with exceedingly low porosity (e.g., near zero) and high loading (e.g., 4 mAh cm−2 ) have not been investigated. Here, we report an intriguing observation that the “zero porosity” NMC electrode can have higher capacity …

Design And Performance Of Superconducting Switches For Nanowire Detectors In Magnetic Fields, Timothy James Draher

Graduate Research Theses & Dissertations

Superconducting nanowire devices fit a broad spectrum of applications, including particle detection and quantum computing, and their expanding use across various fields highlights their role in the hybridization of superconducting and conventional semiconductor electronics. Despite their potential, the low signal output of these devices raises challenges in scalability and integration, particularly in applications for nuclear and high-energy physics, where resilience in magnetic fields is becoming a critical optimization factor. The superconducting nanowire cryotron (nTron) addresses these issues by providing operational gain and logic switching in superconducting nanowire circuits, demonstrating adaptability to multiple materials. This dissertation focuses on modifying the conventional …