Condensed Matter Physics Commons^™

Shear Viscosity Of Quasi One-Dimensional Bec Tubes And Entanglement Negativity Conditions, Camilla Polvara

Dissertations, Theses, and Capstone Projects

Shear Viscosity of Quasi One-dimensional BEC Tubes

We consider layered Bose-Einstein condensates interacting via contact intra-condensate interacions and dipolar inter-condensate potentials, both of which dominate intercondensate tunneling (which we neglect for simplicity). For this system, we compute the normal modes, we study its localization properties by numerically computing the inverse participation ratio, and we compute the inter-tube shear viscosity.

Entanglement Negativity Conditions

This project explores bounds on entanglement negativity using operator inequalities, building on the results of [1]. We are looking for a way to quantify entanglement, as an alternative to calculating the full negativity, which would otherwise require the …

Design, Fabrication, And Spectroscopy Of Photocatalytic Materials In Visible Spectrum, Yamuna Paudel

Dissertations, Theses, and Capstone Projects

Heterogeneous photocatalysis has attracted research interest in sustainable energy technologies. However, achieving high photocatalytic efficiency from visible light-absorbing semiconductors is challenging due to their weak absorption, transport losses, and low activity. While multilayer approaches have been developed to enhance the surface reactivity and stability independent of electronic factors, a comprehensive framework for optimizing light-matter interactions has not yet been established. Here, we introduce a photonic strategy using semiconductor metasurfaces, which is highly effective in enhancing the photocatalytic activity of GaAs, a high-performance semiconductor with a near-infrared bandgap. Our engineered pillar arrays with heights of ~150 nm exhibit Mie resonances near …

Interplay Of Magnetic Impurities And Superconductivity In Topological Materials, Didier Ndengeyintwali

Dissertations, Theses, and Capstone Projects

The interplay of superconductivity and magnetism has been a long-standing topic of interest since the discovery of superconductivity. In recent years it has been shown that topological superconductivity, which has promising applications such as in topological quantum computing, could result from such interplay. Motivated by the later results I study the effect of magnetic impurities in superconducting doped topological insulators, such as Iron based topological superconductors. I show that topological character of parent materials could lead to modifications in the structure of magnetic impurity induced in-gap states. Moreover, the superconductivity induced interaction between magnetic impurities in doped topological insulator would …

Mg3sb2-Based Materials For Mid-Temperature Thermoelectric Application, Veera Prabhu K

Theses and Dissertations

Recently, there has been growing research in the scientific community regarding the conversion of heat flux into electricity, which has proven effective in mitigating energy crises. Solid-state thermoelectric (TE) devices use the Seebeck effect to efficiently convert waste heat into electricity. Traditional materials contain toxic, rare, and expensive elements like Lead, Tellurium, and Germanium that restrict large-scale production, commercialization, and practical utilization.

Recently, Mg3Sb2-based materials have been attractive due to their remarkable characteristics, including abundance, affordability, and environmental friendliness. Furthermore,n-type Mg3Sb2-based materials exhibit high TE performance because of their high band degeneracy in the conduction band minimum (CBM), and low …

Surface Patterning On Zirconia Dental Implants Via Laser-Induced Shockwave Imprinting, Inomjon Majidov

Masters Theses & Specialist Projects

Zirconia is rapidly becoming a preferred alternative to titanium in dental applications, primarily due to its aesthetic resemblance to natural teeth. This material’s tooth-like color avoids the aesthetic issues associated with the grey metal tint of titanium implants. Additionally, zirconia is hypoallergenic, making it an ideal choice for patients with metal sensitivities or allergies. Despite these advantages, zirconia generally exhibits lower biocompatibility and osseointegration compared to titanium implants. This study investigates laser-assisted, controlled imprinting technique on zirconia surfaces to enhance these properties. Our research used zirconia pellets, produced from powdered monoclinic zirconia pressed in a pellet press machine. Two methods …

Synthesis And Characterization Of A Zirconium (Zr) Thin Film On Si(100) Via Pulsed Laser Deposition, Zikrulloh Khuzhakulov

Masters Theses & Specialist Projects

This study investigates the synthesis and characterization of zirconium (Zr) thin films deposited on Si(100) substrates using pulsed laser deposition (PLD). The effects of two laser wavelengths (1064 nm and 532 nm), various substrate temperatures (25 °C, 300 °C, and 500 °C), and different laser fluences (0.25, 0.5, 1.0 J/cm²) on the properties of the Zr films were examined. Results indicated that smoother films were achieved with the 1064 nm wavelength, while surface roughness increased with higher fluences. Optimal crystalline films were obtained at a substrate temperature of 300 °C for both wavelengths. X-ray diffraction (XRD), scanning electron microscopy (SEM), …

Investigations Of Sulfurized Polymers For Their Use In Lithium-Sulfur Cells, Alan M. Rowland

All Theses

With the invention of the Lithium-Ion cell in the latter half of the 20th century, there has been a continued endeavor for innovation in compact energy-storage. Combined with the ever-growing need to move away from fossil fuels, electrochemical energy storage has seen a myriad of research projects in the pursuit of finding the ‘beyond-lithium’ cell. One of these projects that I personally assisted with was lithium-sulfur cells, which allow for a significantly greater energy storage capacity when compared to lithium-ion cells. In investigating a popular cathode in lithium-sulfur cells, sulfurized polyacrylonitrile (SPAN), it was hinted that there may be more …

Modeling Study Of Si3N4 Waveguides On A Sapphire Platform For Photonic Integration Applications, Diandian Zhang, Shui-Qing Yu, Gregory J. Salamo, Richard A. Soref, Wei Du

Electrical Engineering and Computer Science Faculty Publications and Presentations

Sapphire has various applications in photonics due to its broadband transparency, high-contrast index, and chemical and physical stability. Photonics integration on the sapphire platform has been proposed, along with potentially high-performance lasers made of group III–V materials. In parallel with developing active devices for photonics integration applications, in this work, silicon nitride optical waveguides on a sapphire substrate were analyzed using the commercial software Comsol Multiphysics in a spectral window of 800~2400 nm, covering the operating wavelengths of III–V lasers, which could be monolithically or hybridly integrated on the same substrate. A high confinement factor of ~90% near the single-mode …

Electrochemical Characteristics Of Bio-Derived And Silicon-Based Materials For Lithium Ion And Lithium Sulfur Batteries, Nawraj Sapkota

All Dissertations

The increasing demand for advanced batteries, driven by automotive and energy storage needs, emphasizes the need for improved energy density, longevity, and cost-effectiveness. While lithium-ion batteries (LIBs) offer high energy density, their traditional anode and cathode materials are reaching their limits. Innovations in battery chemistry, particularly using sulfur cathodes and silicon-based anodes, are crucial. Sulfur and silicon are attractive due to their abundance, environmental friendliness, and higher theoretical capacities. This research aims to enhance the electrochemical performance of lithium-sulfur batteries using three-dimensional architectures and solid-state electrolytes, and to improve silicon-based materials by modifying their surface architectures.

Chapter 1 reviews the …

Quantum Circuit Optimization Leveraging Multi-Qubit Exchange Interactions In Spin Qubits, Miguel Gonzalo Rodriguez

Open Access Theses & Dissertations

This thesis looks into how multi-qubit exchange interactions can be used to improve quantumcircuits in semiconductor quantum devices. Pairwise interactions between qubits are a common tenet of traditional quantum computing paradigms, although they can impose complexity and depth constraints on circuits. In order to improve the efficiency and scalability of quantum circuits, this research explores the theoretical underpinnings and practical uses of multi-qubit interactions. A thorough theoretical framework is formulated, outlining the mathematical equivalence of a unitary matrix representing interactions between multiple qubits. We obtain the timeevolution operator by analyzing the Hamiltonian of three spin-1/2 particles. A number of quantum …

Studying The Chemistry-Property Relationship In Magnetic And Optical Materials: Spin S = 3/2 Systems Of Neodymium, Manganese, And Cobalt Oxyanions, Xudong Huai

All Dissertations

This dissertation describes the design and tunability of new magnetic and optical materials, emphasizing the intricate relationship between their crystal structures and their optical, electronic, and magnetic properties.

Two new frustrated magnets, ANd(SO₄)₂ (A = Rb, Cs), were designed and synthesized to examine the influence of the the counter cation A site in Nd lanthanide materials featuring a distorted triangular magnetic lattice with S = 3/2. This work demonstrates how the tunability of magnetic and photoluminescent properties can be achieved through the A sites, with findings validated through density functional theory calculations.

AMnTeO₆ (A = Ca, …

Tuning Electronic Transport And Magnetic Properties Of Layered Magnetic Materials, Md Rafique Un Nabi

Graduate Theses and Dissertations

Two-dimensional magnetic materials (2DMMs) have gained significant interest due to their potential for novel physical phenomena and device applications. Mn_2-xZn_xSb, with its tunable magnetic properties and stable tetragonal layered structure, offers a rich platform for exploring these phenomena. The introduction of Zn into the Mn₂Sb lattice efficiently tunes magnetic and electronic properties, making it a compelling candidate for high-performance spintronic devices.

With this motivation, we synthesized Mn_2-xZn_xSb (0 ≤ x ≤ 1) single crystals using a flux method. Mn2Sb exhibits ferrimagnetic order below 550 K with antiparallel spins aligned along …

Settingsorder Article Reprints Open Accessarticle A Model To Account For The Effects Of Load Ratio And Hydrogen Pressure On The Fatigue Crack Growth Behavior Of Pressure Vessel Steels, Ashok Saxena, Kip O. Findley

Mechanical Engineering Faculty Publications and Presentations

A phenomenological model for estimating the effects of load ratio R and hydrogen pressure P_H2 on the hydrogen-assisted fatigue crack growth rate (HA-FCGR) behavior in the transient and steady-state regimes of pressure vessel steels is described. The "transient regime" is identified with crack growth within a severely embrittled zone of intense plasticity at the crack tip. The "steady-state" behavior is associated with the crack growing into a region of comparatively lower hydrogen concentration located further away from the crack tip. The model treats the effects of R and P_H2 as being functionally separable. In the transient …

Quantum Classical Algorithm For Solving The Hubbard Model Via Dynamical Mean-Field Theory, Anshumitra Baul

LSU Doctoral Dissertations

Modeling many-body quantum systems is widely regarded as one of the most promising applications for near-term noisy quantum computers. However, in the near term, system size limitation will remain a severe barrier for applications in materials science or strongly correlated systems. A promising avenue of research is to combine many-body physics with machine learning for the classification of distinct phases. I present a workflow that synergizes quantum computing, many-body theory, and quantum machine learning (QML) for studying strongly correlated systems. In particular, it can capture a putative quantum phase transition of the stereotypical strongly correlated system, the Hubbard model. Following …

Twist-Assisted All-Antiferromagnetic Tunnel Junction In The Atomic Limit, Yullang Chen, Kartik Samanta, Naafls A. Shahed, Haojle Zhang, Chi Fang, Arthur Ernst, Evgeny Y. Tsymbal, Stuart S.P. Parkin

Nebraska Center for Materials and Nanoscience: Faculty Publications

Antiferromagnetic spintronics^1,2 shows great potential for high-density and ultrafast information devices. Magnetic tunnel junctions (MTJs), a key spintronic memory component that are typically formed from ferromagnetic materials, have seen rapid developments very recently using antiferromagnetic materials3,4. Here we demonstrate a twisting strategy for constructing all-antiferromagnetic tunnel junctions down to the atomic limit. By twisting two bilayers of CrSBr, a 2D antiferromagnet (AFM), a more than 700% nonvolatile tunnelling magnetoresistance (TMR) ratio is shown at zero field (ZF) with the entire twisted stack acting as the tunnel barrier. This is determined by twisting two CrSBr monolayers for which the TMR …

Laser 3d Printing Of Diamond-Based Composite Materials For Thermal Management Applications, Nada Kraiem

Dissertations and Doctoral Documents, University of Nebraska-Lincoln, 2023–

With the trend towards miniaturization of electrical equipment and the constant increase in power density in semiconductor devices, efficient heat management has become a major concern for researchers. Indeed, this technological evolution imposes increasingly strict constraints in terms of thermal dissipation, necessitating innovative solutions to ensure better durability and reliability of components. In this context, the use of composite materials offering high thermal conductivity (TC) and low coefficient of thermal expansion (CTE) compared to pure metals has become essential to address overheating issues in electronic components.

The utilization of advanced materials such as diamond (D), with exceptional TC and hardness …

Dual Light Emission Of Cssni3-Based Powders Synthesized Via A Mechanochemical Process, Xuan Huang, Xiaobing Tang, Xiyu Wen, Yuebin Charles Lu, Fuqian Yang

Chemical and Materials Engineering Faculty Publications

Lead toxicity has hindered the wide applications of lead halide perovskites in optoelec- tronics and bioimaging. A significant amount of effort has been made to synthesize lead-free halide perovskites as alternatives to lead halide perovskites. In this work, we demonstrate the feasibility of synthesizing CsSnI3-based powders mechanochemically with dual light emissions under ambi- ent conditions from CsI and SnI2 powders. The formed CsSnI3-based powders are divided into CsSnI3-dominated powders and CsSnI3-contained powders. Under the excitation of ultraviolet light of 365 nm in wavelength, the CsSnI3-dominated powders emit green light with a wavelength centered at 540 nm, and the CsSnI3-contained powders …

Effects Of Differing Radiation Methods On Charge Transport In Polymers, Zachary Gibson, Jr Dennison, Virginie Griseri

Presentations

The mitigation of deleterious arcing and sparking onboard spacecraft depends upon a thorough understanding of the electrical properties of the materials involved. This includes not only understanding steady-state parameters such as dark conductivity, but responses to the space environment as well. For example, radiation-induced conductivity drastically changes the conductivity of a material due to the presence of radiation. However, this change in conductivity diminishes away once the radiation is no longer present. There may also be permanent changes, or aging, in the material properties. The physical processes of aging can be complicated and are often difficult to model. Therefore, empirical …

Unveiling Ferroelectric And Multifunctional Insights In Hybrid Formate Perovskites, Abduljelili Popoola

USF Tampa Graduate Theses and Dissertations

Formate perovskites, denoted as AB(HCOO)3, represent a diverse group of hybrid organic-inorganic compounds, renowned for their numerous phase transitions and a wide array of properties. These properties encompass (anti)ferroelectricity, ferroelasticity, (anti)ferromagnetism, and multiferroism. Despite extensive research on these materials, a comprehensive examination of their properties across a substantial number of formate perovskites remains scarce. This scarcity stems from structural complexity of these materials, potential systematic errors arising from different measurement techniques or incomplete data. For instance, data for critical parameters like piezoelectricity, dielectricity, and elasticity tensors have been lacking.

In this study, we address these challenges by employing first-principles density …

Spin And Charge Transport In Metallic Ferrimagnets And Disordered Magnetic Oxides, Leopoldo A. Hernandez

Electronic Theses and Dissertations

Recent efforts have been exploring the use of thin film synthetic ferrimagnets and disordered magnetic oxides for applications in spintronic devices. Due to the antiferromagnetic exchange interaction, ferrimagnetic materials offer the ultrafast dynamics of the antiferromagnetic exchange, with a net magnetization that can be influenced externally. With two, or more, competing ferromagnet sublattices, interesting properties arise that depend on the final magnetic landscape after growth of the material and it’s inherent magnetic anisotropy energies. Properties such as magnetic compensation temperatures, and perpendicular magnetic anisotropy are attractive for applications in spintronic memory and logic devices, some already being implemented in MRAM …

Radiation Induced Conductivity Of Peek: Effects Of Temperature And Total Ionizing Dose, Joshua Boman, Brian Wood, Jordan Lee, Jr Dennison, Kim M. Aaron, Wousik Kim

Conference Proceedings

Radiation induced conductivity (RIC) plays a critical role in space charge dissipation with insulating materials used in spacecraft. Ionizing radiation present in harsh space plasma environments deposits energy into materials via inelastic scatter, exciting electrons into the conduction band without depositing charge for penetration radiation. RIC is expected to be affected by temperature and total ionizing dose (TID); temperature primarily affects the rate of promotion of electrons in localized trap states within the band gap to the conduction band, while TID can create additional traps states thereby increasing trap density and reducing mean trap separation.

RIC was measured in a …

Temperature Dependent Radiation Induced Conductivity Of Polymeric Spacecraft Materials, Jodie Corbridge Gillespie, Jr Dennison

Conference Proceedings

Temperature dependent radiation induced conductivity (RIC) data applicable to conditions experienced by spacecraft are presented for low density polyethylene (LDPE) and poylimide (PI, Kapton^HN, along with summaries for five other common polymeric spacecraft mateials: polyimide (PI; Kapton HN^TM, and Kapton E^TM), polytetraflouroethylene (PTFE; Teflon^TM), expanded PTFE (ePTFE), ethylene-tetrafluoroethylene and (ETFE; Tefzel^TM). Data were measured over approximately 105 K to 330 K and incident dose rates, D, of 10^-4 Gy/s to 10^-1Gy/s. Theoretical expressions proposed by Rose/Fowler/Vissenberg predict equilibrium RIC behavior according to a general expression σ …

Time-Dependent Behavior Of Radiation Induced Conductivity In Polymers, Tyler Heggenes, Jenny R. Whiteley, Jodie Corbridge Gillespie, Joshua Boman, Jr Dennison

Conference Proceedings

Ionizing radiation can induce conductivity in polymers via inelastic scattering which imparts energy to electrons in the valence band and trapped states, exciting them into the conduction band without depositing charge into the material. This radiation-induced conductivity (RIC) can impact space charge dissipation within highly insulating materials used in spacecraft in harsh space plasma environments. Previous USU research analyzed only the equilibrium portions of an extensive RIC database for polymeric materials, including Kapton HN^TM. This confirmed that equilibrium RIC follows a standard theoretical model that is temperature and dose-dependent. The current study provides a new analysis of RIC's …

Comparison Of Absolute Electron Emission Yields Of Extreme Insulators: Round Robin Tests Of Polyimide And Low Density Polyethylene, Jr Dennison, Matthew Robertson, Christopher Vega, Mohamed Belhaj, Juste Sarah Dadouch, Isabel Montero, María E. Dávila, Kazuhiro Toyoda

Posters

No abstract provided.

Temperature Dependent Radiation Induced Conductivity Of Polymeric Spacecraft Materials, Jodie Corbridge Gillespie, Jr Dennison

Posters

No abstract provided.

Analysis Of The Effects Of Surface Modifications And Other Extrinsic Factors On Electron Yield With A “Patch” Model, Matthew Robertson, Christopher Vega, Trace Taylor, Jr Dennison

Presentations

Electron yield (EY) is a material attribute of central importance to understanding and modeling spacecraft charging. EY is defined as the ratio of emitted electrons to incident electrons, when irradiated with an electron beam. It depends on incident energy and is unique for each material as determined by its chemical composition, crystal structure, and electronic configurations. Dynamic surface modifications and other extrinsic factors—including surface morphology, composition, contamination, oxidation, and charging— can significantly affect EY and consequently spacecraft charging. This research proposes a “patch” model to provide a simple theoretical framework to model more complex materials comprised of any number of …

Time-Dependent Behavior Of Radiation Induced Conductivity Of Polymers, Tyler Heggenes, Jenny R. Whiteley, Jodie Corbridge Gillespie, Joshua Boman, Jr Dennison

Presentations

The conductivity of insulating materials can be enhanced above the baseline dark conductivity by incident radiation via inelastic scattering that imparts energy to electrons in trapped states and excites them into the conduction band, without depositing charge. Such radiation-induced conductivity (RIC), caused by ionizing radiation present in harsh space plasma environments, can play a critical role in space charge dissipation within highly insulating materials used in spacecraft. An equilibrium value for RIC, 𝜎_RIC, is attained after prolonged exposure to an incident dose rate; this follows a standard theoretical power law model proposed by Rose/Fowler/Vissenberg, 𝜎_RIC(T …

Analysis Of The Effects Of Surface Modifications And Other Extrinsic Factors On Electron Yield With A “Patch” Model, Matthew Robertson, Christopher Vega, Trace Taylor, Jr Dennison

Conference Proceedings

Electron yield (EY) is a material property of central importance to understanding and modeling spacecraft charging. It depends on incident energy and is unique for each material. Dynamic surface modifications and other extrinsic factors—including composition, surface morphology, contamination, oxidation, and charging— can significantly affect EY and consequently spacecraft charging. This research proposes a “patch” model to provide a simple theoretical framework to model more complex materials comprised of any number of different types of constituent materials in terms of the EY contribution of each constituent material or extrinsic factor. The “patch” model merges the unique EY curve contribution of each …

Effects Of Differing Radiation Methods On Charge Transport In Polymers, Zachary J. Gibson, Jr Dennison, Virginie Griseri

Conference Proceedings

Spacecraft charging issues are understood and mitigated through an understanding of material properties. Material properties are dynamic in the harsh environment of space. Approximations must be made to simulate the space environment in the laboratory. This paper reports on the investigation of the approximation that energy deposition causes the same aging effects in the materials regardless of the radiation source. Samples of polytetrafluoroethylene (PTFE) and polyether-etherketone (PEEK) were irradiated with x-rays, γ-rays, or electrons at total ionizing dose (TID) of either 2 x 10⁴, 2 x 10⁵, or 2 x 10⁶ rad. Charge was then …

Photodegradation Of Microplastics Through Nanomaterials: Insights Into Photocatalysts Modification And Detailed Mechanisms, Yiting Xiao, Yang Tian, Wenbo Xu, Jun Zhu

Biological and Agricultural Engineering Faculty Publications and Presentations

Microplastics (MPs) pose a profound environmental challenge, impacting ecosystems and human health through mechanisms such as bioaccumulation and ecosystem contamination. While traditional water treatment methods can partially remove microplastics, their limitations highlight the need for innovative green approaches like photodegradation to ensure more effective and sustainable removal. This review explores the potential of nanomaterial-enhanced photocatalysts in addressing this issue. Utilizing their unique properties like large surface area and tunable bandgap, nanomaterials significantly improve degradation efficiency. Different strategies for photocatalyst modification to improve photocatalytic performance are thoroughly summarized, with a particular emphasis on element doping and heterojunction construction. Furthermore, this review …