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Study Of Morphology, Structure, And Magnetic Properties Of High Entropy Alloy Systems, Matthew G. Guerrero

Open Access Theses & Dissertations

Abstract:This thesis presents an investigation into the magnetic properties of high entropy alloy (HEA) samples, focusing primarily on compositions within the FeNiCoMn system and their gallium/chemically doped derivatives. High entropy alloys represent a promising class of materials with unique properties resulting from their complex composition and structural arrangements. The behavior of these alloys, particularly in their magnetic properties, remains an area of significant interest due to their potential applications in magnetic storage, sensing, and other technological domains. The study encompasses an examination of seven distinct HEA samples: FeNiCo, FeNiCoMn0.2, FeNiCoMn0.4, FeNiCoMn0.6, FeNiCoMn0.2Ga0.1, FeNiCoGa0.2, FeNiCoMn0.2Ga0.3. Furthermore, three samples of FeNiCoMn0.2 and …

Manipulation Of The Magnetic Properties Of Van Der Waals Materials Through External Stimuli, Luis Martinez

Open Access Theses & Dissertations

A new revolutionary application dependent on the electron spin to carry information with greater efficiency in data storage, transfer, and processing, will rely heavily on 2D magnets and the ability to effectively control their electron spins and engineer their properties. Previously, magnetic thin films were heavily studied to achieve this goal, however, these materials came with pitfalls and lacked naturally occurring 2D magnetism. The recent discovery of intrinsic magnetism in few-layered van der Waals (vdW) magnets has inspired researchers to extensively study them because of the feasibility to exfoliate them down to a monolayer. Due to this dimensionality factor, vdW …

Compound Marine Cold Spells And Hypoxic Events In A Nearshore Upwelling System, Ryan K. Walter, Michael Dalsin, Piero L.F. Mazzini, Cassia Pianca

Physics

Prolonged periods of extreme warm and cold seawater temperature anomalies, known as marine heatwaves (MHWs) and marine cold spells (MCSs), respectively, can have significant impacts on coastal marine ecosystems. Prior research has examined the co-occurrence of multiple extremes [low dissolved oxygen (DO) and/or low pH] during MHWs, with the impact of these compound events potentially exceeding that of a single stressor due to synergistic effects. However, we are not aware of any studies that have examined compound extreme events during MCSs, despite the ecosystem implications. Along Eastern Boundary Current Upwelling Systems (EBUS), strong-wind driven upwelling has led to …

Simulation And Design Of Ion Traps Using The Method Of Fundamental Solutions, Trevor Taylor

UNLV Theses, Dissertations, Professional Papers, and Capstones

In this thesis I apply the numeric method, the Method of Fundamental Solutions (MFS), to solve for the fields create by ion traps in various configurations, such as quadrupole ion traps, linear ion traps, toroidal ion traps, and toroidal surface ion traps. The traps are then designed to maximize desired qualities such as minimization of their anharmonicity, and their ability to shuttle ions. A particular focus will be on the toroidal surface ion trap, as well as its ability to shuttle ions. This trap is planned for future experiments involving measurement of the electron Electric Dipole Moment.

Two-Photon Quantum Gates With Single Atoms, Arkan Mahmood Hassan

Graduate Theses and Dissertations

In the first part of this dissertation we study in detail the interaction of single-photon and two-photon wavepackets with a three-level V-type atom in a cavity without any control over the interaction time. We solve analytically for the spectrum of the outgoing wavepackets as a function of the incident wavepacket that is valid in all the cavity limits. We consider the potential performance of this system as a CPHASE gate by considering several special input pulses. We optimize for the gate fidelity and find values of the cavity, atomic and pulse parameters that yield a conditional phase shift of π, …

Time Resolved X-Ray Spectroscopy Of Highly Charged Ar, Nd, And Pr, Timothy Burke

All Dissertations

Highly Charged Ions (HCIs) may be considered ideal mini-laboratory in which one can study the physics of matter and light in an environment of high internal electric field that can not be recreated with standard lab equipment. The remaining electron(s) exist in the extremely large electric field of the nucleus and therefore measurements of electronic transitions in these systems provide stringent tests of our understanding of physics in extreme conditions. Quantum electrodynamics (QED) despite being a powerful theory exhibits large discrepancies for systems under extreme conditions. The work here investigates the atomic properties within non-Maxwellian plasmas. The HCI plasmas studied …

Crystalline Colloidal Arrays: Exploring Light-Matter Interactions, Haley W. Jones

All Dissertations

Understanding and manipulating quantum light-matter interactions, especially in the context of nanostructured environments, is highly critical for technological progress and inventive solutions in the fields of telecommunications, energy-efficient lighting, and cutting-edge quantum computing technologies. The fundamental interactions of photons with a surrounding environment directly impact the performance and efficiency of devices such as lasers, light-emitting diodes (LEDs), and quantum computing elements, which leverage the unique properties of confined structured environments. Since the late 1980s, the connection between a structured environment and the decay kinetics of an embedded fluorophore has been a highly debated and unresolved topic in the literature. More …

Design, Fabrication, And Characterization Of Advanced High-Power Single-Mode 9xxnm Semiconductor Lasers, Xiaolei Zhao

All Dissertations

This thesis presents the comprehensive design, fabrication, and demonstration of advanced high-power, high-efficiency single-mode semiconductor lasers operating at a wavelength of 9xxnm. We begin with the design of the laser epitaxial structure, serving as the cornerstone for achieving high-power high-efficiency lasers. Our methodology integrates a semi-analytical calculation model, which accounts for Longitudinal Spatial Hole Burning (LSHB) and Two-Photon Absorption (TPA) effects, facilitating a thorough exploration of how design parameters influence output power and conversion efficiency. This approach offers an effective and time-efficient epitaxial structure optimization strategy compared to conventional full 3D simulation models.

Subsequently, we demonstrate high-power, high-efficiency ridge waveguide …

Oscillations Of Capillary Surfaces With Volume And Edge Effects, Dingqian Ding

All Dissertations

Capillary surfaces are defined by an interface endowed with surface tension that is partially supported by a solid substrate and are susceptible to oscillations reflecting a balance between fluid inertia and the restorative force of surface tension. The wave dynamics strongly depend upon volume change within the domain and edge effects through the boundary conditions applied at the contact-line formed at the liquid-gas-solid interface, while the spatial wave structure conforms to the geometry of the capillary surface. This dissertation develops mathematical models to address these effects for several canonical capillary surfaces, which are organized into two parts that are focused …

Experimental Analyses Of Emission Lines In The Uv/Vis/Nir Range For Astrophysically-Important Elements: From The Iron Group To R-Process Elements, Brynna Neff

All Dissertations

Analysis of astrophysical phenomena requires an understanding of the electronic

structure and transition probabilities of the elements present in that environment,

yet there are still many charge states of heavy elements whose electronic

structures and spectroscopic properties are not yet well understood. To address this,

we investigated the spectroscopic properties of three different elements through an

analysis of spectra collected from three different experimental apparatuses.

In order to better understand the spectroscopic properties of Ni I and II, we

analyzed spectra collected from the Compact Toroidal Hybrid (CTH) apparatus at

Auburn University. In this experiment, a nickel sample was inserted …

Investigate The Importance Of Local Magnetic Moment And Magnetic Interaction In Superconducting Fese Monolayer Using Density Functional Calculations, Sudip Pokharel

Graduate Theses and Dissertations

In this dissertation, we present two projects to study superconducting FeSe monolayer using first-principles density functional calculations. Monolayer FeSe/SrTiO₃ system has very different properties as compared to its bulk counterpart in terms of critical superconducting temperature, Fermi surface topology and antiferromagnetic (AFM) stability. For FeSe monolayer, local magnetic moment (LMM) and AFM fluctuation are closely linked to superconductivity. However, LMM is not studied enough for FeSe monolayer. For FeSe/SrTiO₃ system, the substrate SrTiO₃ constrains the in-plane lattice constant for FeSe and also plays a crucial role in the onset and enhancement of superconductivity by providing charge transfer. …

Blade Design And Validation Of Hydrokinetic Turbine To Harvest Water Current Energy, Setare Sadeqi

LSU New Orleans Theses and Dissertations

The innovative aspect of this research lies in the careful integration of cutting-edge technologies throughout the entire process of designing, fabricating, and testing the carbon fiber propeller for the 3-bladed horizontal axis ocean current turbine (OCT). SolidWorks software played a pivotal role in the initial design phase, enabling a meticulous and precise modeling of the propeller's geometry. The utilization of SolidWorks allowed for a detailed exploration of various design parameters, ensuring that the propeller's structure and form were optimized for performance in ocean current conditions. Moving beyond the realm of virtual design, the choice of carbon fiber as the fabrication …

Perovskite Materials For Optoelectronics Applications: Solar Cells And Photodetectors, Abdul Kareem Kalathil Soopy

Dissertations

Perovskite materials have emerged as promising candidates for optoelectronic applications, particularly in solar cells and photodetectors, due to their remarkable properties such as high carrier mobility, tunable bandgap, and low-cost fabrication. This thesis explores two novel approaches, namely monovalent doping and bulk as well as surface passivation, to enhance the performance and stability of perovskite-based devices.

The primary goal of this research is to enhance the properties of perovskite materials to improve their optoelectronic performance, aiming to broaden their use in solar cells and photodetector devices. Specifically, this study seeks to evaluate the effectiveness of Cu doping and Zinc porphyrin …

Biomass Estimation Of Mature Mangrove Trees In The Uae Using Spaceborne Remote Sensing Techniques, Yasmine Ashraf Heikal

Theses

Mangrove forest ecosystems play an essential role in diminishing the effects of climate change caused by the increase in carbon dioxide in the atmosphere. Estimating mangrove forest aboveground biomass (AGB) and hence aboveground carbon (AGC) can assist in decision-making for conservation, sustainable use, and protection of these forests. The goal of this research project was to map the AGB of mangrove forests along the coasts of the United Arab Emirates (UAE) with the aid of Landsat-8-9 satellite imagery data acquired in September 2023. 12 AGB estimation models were developed based on the combination of in situ measurements and Landsat-8-9 derived …

Redesign Of X-Ray Irradiator To Expand Research Of Low-Dose X-Ray Radiation, Lauren Ulbrich

All Theses

The effects of high-dose radiation are well-documented, and are understood to be harmful to the human body. On the other hand, the effects of low-dose radiation are much less understood. There is debate over whether or not there are negative, positive, or no effects at all from low-dose radiation. One of the reasons why these effects are not well known is because there aren't as many studies done on this type of radiation. It is a lot harder to classify the effects of radiation at low doses due to many external factors. However, the Clemson Medical Physics lab has been …

Mechanical And Thermal Measurement Techniques For Crystalline-Core/Crystalline-Clad Optical Fibers, Evan Watkins

All Theses

Optical fiber laser systems offer advantages such as high optical gain, efficient cooling, and the production of high-quality optical beams. Fiber lasers are characterized by their unique core-cladding structure, providing optical benefits and mechanical properties that impact their performance. Interests in materials such as yttrium aluminum garnets (YAG) and lutetium oxide (Lu2O3 also lutetia) as laser mediums are due to their high average power capabilities, but thermal management remains a challenge. This thesis discusses the choice of ytterbium (Yb3+) as a dopant in YAG and lutetia, exploring its electronic structure and relevance to thermal properties. The thesis focuses on the …

Photobiomodulation Of Bovine Oocytes During Maturation Increases Atp Content And Enhances Subsequent Embryonic Development, Kendall Richey

All Theses

Bovine in-vitro production(IVP) of embryos is a growing field for producing offspring with desirable genetics in the cattle industries. While IVP is effective, oocyte cytoplasmic maturation is compromised, and bovine oocytes matured in-vitro have reduced metabolic activity than those matured in-vivo. Mitochondria are the central unit of oocyte metabolism, producing ATP through OXPHOS. Photobiomodulation is a light treatment reported to improve metabolic activity. In five experiments, we measured the effects of photobiomodulation treatment with red LED at 16-(L-16) and 20 h(L-20) of bovine oocyte in-vitro maturation on subsequent embryonic development, mitochondrial activity and nuclear progression. Bovine COCs were aspirated …

Computational Study For Tissue-Specific Dosimetric Quantities Of Secondary Radiation For Mars Exploration, Sungmin Pak

UNLV Theses, Dissertations, Professional Papers, and Capstones

The two main sources of primary space radiation, Galactic Cosmic Rays (GCRs) and Solar Particle Events (SPEs), encompass a spectrum of ions, ranging from protons (Z=1) to nickel ions (Z=28), with energies spanning from less than 1 keV to exceeding a few TeV. While SPEs represent sporadic events primarily comprised of a high flux of low- to intermediate-energy protons, GCRs are characterized by continuous low flux of diverse ions with higher energies, peaking in intensity near the solar minimum. During a Mars mission, astronauts will encounter primary particles of high energy from GCR and SPE spectra, capable of penetrating spacecraft …

Studying Superconducting Thin Films For Quantum Computing Applications, Bernardo Jaime Langa Junior

All Theses

Superconducting qubits have emerged as a promising platform for realizing error-corrected quantum computing. Reaching the minimum threshold for error correction requires scaling the number of qubits well beyond the current numbers while improving their coherence and minimizing their crosstalk. Such daunting demands require groundbreaking innovations in the design of superconducting quantum circuits as well as in engineering the materials integrated into the devices. This thesis explores materials solutions for two different scalability problems: 1) crosstalk and 2) loss due to surface oxidation. The crosstalk is addressed by making voltage-tunable superconductor-semiconductor Josephson junctions (JJs). For the loss due to surface oxidation, …

Investigation Of Domain Formation During Phase Separation In A Mixture Of Flexible And Rigid Biopolymers, Steven Huntley

All Theses

Complex fluids and heterogenous mixtures composed of multiple types of polymers are found throughout industrial and biological fluid systems. For example, extrusion based additive manufacturing systems pass dense mixtures of polymers through the extrusion heads to deposit composite polymeric materials. In cells, active and complex mixtures of biopolymers self-organize into assemblies that perform critical physiological functions.

Polymers in dense solutions undergo phase separation as a result of differences in physiochemical properties. A few examples of these properties include charge, structure, rigidity, and hydrophobicity. We observe the formation of polymer domains composed of rigid and a flexible biopolymer species that phase …

Exploring The Coronal Magnetic Field With Galactic Cosmic Rays: The Sun Shadow Observed By Hawc, R. Alfaro, C. Alvarez, J. C. Arteaga-Velázquez, K. P. Arunbabu, D. Avila Rojas, R. Babu, Et Al.

Michigan Tech Publications

Galactic cosmic rays (GCRs) are charged particles that reach the heliosphere almost isotropically in a wide energy range. In the inner heliosphere, the GCR flux is modulated by solar activity so that only energetic GCRs reach the lower layers of the solar atmosphere. In this work, we propose that high-energy GCRs can be used to explore the solar magnetic fields at low coronal altitudes. We used GCR data collected by the High-Altitude Water Cherenkov observatory to construct maps of GCR flux coming from the Sun’s sky direction and studied the observed GCR deficit, known as Sun shadow (SS), over a …

Better Light Than Never: A New Radiative Mechanism For Observing Binary Black Holes, Paul Rioles

Graduate Masters Theses

Black holes are notoriously elusive, they are impossible to observe directly, and cur- rent methods of extracting information from behind their cosmic camouflage are both limited in number and experimentally difficult. The scope of this investigation is to ex- plore a proposed novel radiative mechanism for active similar mass binary black holes, affording new observational methods to investigate frequency inspirals of BH mergers. The explored mechanism is a result of each BH’s accretion of the surrounding plasma, creating voids that orbit throughout the plasma. The significant results described in this thesis include expressions for the frequency, power radiated per unit …

Disconnectivity Graphs Of Spin Glasses On The Kagome Lattice, Richard Richardson

Honors Theses

The topology of the potential energy landscape for a spin-glass arranged on the Kagome lattice is studied by the use of enhanced disconnectivity graphs. Enhanced disconnectivity graphs display location and type of minima structures and the barrier heights between them. Three different models which differ in the range of allowed values for the bond strength are analyzed. The allowed values for bond strength for the three different models are {±1}, {±1, ±2}, and {±1, ±2, ±3}. 100 systems were randomly generated for each model, and enhanced disconnectivity graphs were drawn for each system by using the Hamiltonian of the Ising …

Crystallographic Defects In Weyl Semimetal Laalge, Inseo Kim, Byungkyun Kang, Hyunsoo Kim, Minseok Choi

Physics Faculty Research & Creative Works

Crystallographic Defects in a Topological Semimetal Can Result in Charge Doping and Scattering Centers Which May Mask the Exotic Spectroscopic and Transport Properties, respectively. Here, We Investigate the Possible Crystallographic Defects Including Vacancy and Antisite in Weyl Semimetal LaAlGe using Hybrid-Density-Functional Theory Calculations. We Show that a Considerable Concentration of Al- and Ge-Related Defects Naturally Form during Growth Due to their Low Formation Enthalpy. Specifically, Al Can Be Easily Replaced by Ge in the I41md Phase of LaAlGe, Forming the Ge-On-Al Antisite, GeAl. the Counterpart, Al-On-Ge (AlGe), is Also Probable. the Most Abundant Defect GeAl is Donorlike, Effectively Electron Doping, …

Deterministic Global 3d Fractal Cloud Model For Synthetic Scene Generation, Aaron M. Schinder, Shannon R. Young, Bryan J. Steward, Michael L. Dexter, Andrew Kondrath, Stephen Hinton, Ricardo Davila

Faculty Publications

This paper describes the creation of a fast, deterministic, 3D fractal cloud renderer for the AFIT Sensor and Scene Emulation Tool (ASSET). The renderer generates 3D clouds by ray marching through a volume and sampling the level-set of a fractal function. The fractal function is distorted by a displacement map, which is generated using horizontal wind data from a Global Forecast System (GFS) weather file. The vertical windspeed and relative humidity are used to mask the creation of clouds to match realistic large-scale weather patterns over the Earth. Small-scale detail is provided by the fractal functions which are tuned to …

Divergence-Free Tensor Densities In Two Dimensions, Tyler Hansen

All Graduate Theses and Dissertations, Fall 2023 to Present

In physics, a common method for exploring the way a physical system changes over time is to look at the system’s energy. Roughly speaking, the energy in these systems are either motion-based (kinetic energy, a bullet in flight) or position-based (potential energy, a rock sitting at the top of a hill). The difference between the system’s total kinetic and potential energies is quantified by an expression called the Lagrangian. Using a special procedure, this Lagrangian is massaged to produce a group of equations called the Euler-Lagrange equations; if the initial configuration of the system is provided, the solution to these …

Spin Disorder Control Of Topological Spin Texture, Hongrui Zhang, Yu-Tsun Shao, Xiang Chen, Binhua Zhang, Tianye Wang, Fanhao Meng, Kun Xu, Peter Meisenheimer, Xianzhe Chen, Xiaoxi Huang, Piush Behera, Sajid Husain, Tiancong Zhu, Hao Pan, Yanli Jia, Nick Settineri, Nathan Giles-Donovan, Zehao He, Andreas Scholl, Alpha N'Diaye, Padraic Shafer, Archana Raja, Changsong Xu, Lane W. Martin, Michael F. Crommie, Jie Yao, Ziqiang Qiu, Arun Majumdar, Laurent Bellaiche, David A. Muller, Robert J. Birgeneau, Ramamoorthy Ramesh

Physics Faculty Publications and Presentations

Stabilization of topological spin textures in layered magnets has the potential to drive the development of advanced low-dimensional spintronics devices. However, achieving reliable and flexible manipulation of the topological spin textures beyond skyrmion in a two-dimensional magnet system remains challenging. Here, we demonstrate the introduction of magnetic iron atoms between the van der Waals gap of a layered magnet, Fe₃GaTe₂, to modify local anisotropic magnetic interactions. Consequently, we present direct observations of the order-disorder skyrmion lattices transition. In addition, non-trivial topological solitons, such as skyrmioniums and skyrmion bags, are realized at room temperature. Our work highlights …

Algorithm-Based Linearly Graded Compositions Of Gesn On Gaas (001) Via Molecular Beam Epitaxy, Calbi Gunder, Mohammad Zamani-Alavijeh, Emmanuel Wangila, Fernando Maia De Oliveira, Aida Sheibani, Serhii Kryvyi, Paul C. Attwood, Yuriy I. Mazur, Shui-Qing Yu, Gregory J. Salamo

Physics Faculty Publications and Presentations

The growth of high-composition GeSn films in the future will likely be guided by algorithms. In this study, we show how a logarithmic-based algorithm can be used to obtain high-quality GeSn compositions up to 16% on GaAs (001) substrates via molecular beam epitaxy. Herein, we use composition targeting and logarithmic Sn cell temperature control to achieve linearly graded pseudomorph Ge_1−xSn_x compositions up to 10% before partial relaxation of the structure and a continued gradient up to 16% GeSn. In this report, we use X-ray diffraction, simulation, secondary ion mass spectrometry, and atomic force microscopy to analyze and …

Search For Gravitational-Wave Transients Associated With Magnetar Bursts In Advanced Ligo And Advanced Virgo Data From The Third Observing Run, R. Abbott, Michael G. Benjamin, Teviet Creighton, Mario C. Diaz, Francisco Llamas, Soma Mukherjee, Gaukhar Nurbek, Volker Quetschke, Wenhui Wang

Physics & Astronomy Faculty Publications

Gravitational waves are expected to be produced from neutron star oscillations associated with magnetar giant flares and short bursts. We present the results of a search for short-duration (milliseconds to seconds) and long-duration (∼100 s) transient gravitational waves from 13 magnetar short bursts observed during Advanced LIGO, Advanced Virgo, and KAGRA's third observation run. These 13 bursts come from two magnetars, SGR 1935+2154 and Swift J1818.0−1607. We also include three other electromagnetic burst events detected by Fermi-GBM which were identified as likely coming from one or more magnetars, but they have no association with a known magnetar. No magnetar giant …

Improving Static Cold Storage Life Of The Human Heart Before Transplant, Juan Sebastian Rodriguez Paez

Theses and Dissertations

Organ storage and transportation are critical steps for the success of organ transplantation. Static cold storage (SCS) of hearts for heart transplantation (HTx) remains the standard approach. However, SCS may involve damage to the tissue resulting from extended hypothermic preservation, potentially affecting organ viability. More over, the temperature distribution on and within the heart is unknown during heart transplantation. Therefore, there is an interest to study different stages of the heart transplantation process towards determining the 3D temperature distribution on and within the heart. There could be a possibility of having a hypothermic injury in different parts of the heart …