Condensed Matter Physics Commons^™

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 …

Aspects Of Parity Breaking In Classical And Quantum Fluids, Dylan J. Reynolds

Dissertations, Theses, and Capstone Projects

Parity-breaking is ubiquitous across many scales of physics, from the rotation of galaxies at the largest of scales, to the cyclotron orbits of electrons at the microscopic scale. In describing the collective dynamics of many particle systems, parity breaking effects typically originate from some form of chirality, such as angular momentum, at the level of the constituent particles. External forces can also induce chiral motion, with the primary examples being the Lorentz and Coriolis forces.

The effects of parity breaking are perhaps most strikingly seen in active matter, systems of complex particles that tend to convert energy into some directed …

Quantics Tensor Trains: The Study Of A Continuous Lattice Model And Beyond, Aleix Bou Comas

Dissertations, Theses, and Capstone Projects

This four-chapter dissertation studies the efficient discretization of continuous variable functions with tensor train representation. The first chapter describes all the methodology used to discretize functions and store them efficiently. In this section, the algorithm tensor renormalization group is explained for self-containment purposes. The second chapter centers around the XY model. Quantics tensor trains are used to describe the transfer matrix of the model and compute one and two-dimensional quantities. The one dimensional magnitudes are compared to analytical results with an agreement close to machine precision. As for two dimensions, the analytical results cannot be computed. However, the critical temperature …

Development And Application Of Magnus Expansion Based Propagators For Problems In Spectroscopy And Quantum Dynamics, Taner M. Ture

Dissertations, Theses, and Capstone Projects

Stable and accurate numerical propagators of time-evolution equations in quantum mechanics are required to capture correct dynamical behavior, especially in the long time limit. Magnus expansion (ME) provides a general way to expand the real time propagator of a time dependent Hamiltonian within the exponential such that the unitarity is satisfied at any order. Integrators are developed by truncating the ME and using explicit integration of Lagrange interpolation formulas for the time dependent Hamiltonian within each time interval. The derived approximations are studied in a numerical test and compared to other available expressions. The sixth order expression is applied to …

Effects Of Ti Addition On The Characteristics Of Al-10zn-6mg-2si/Zro2 Composites Produced By Squeeze Casting, Qesha Diva Prameshvara, Pipin Indah Lestari, Bondan Tiara Sofyan

Journal of Materials Exploration and Findings

Metal matrix composite (MMC) with 7xxx aluminum matrix is potential for ballistic applications due to the combination of strength, toughness, and light weight. Previous study successfully produced aluminum-based composites with SiC particles which were able to stop type III bullet, however cracks remained on back of the plate. Therefore, in this research, SiC was replaced by zirconia (ZrO₂) due to its high fracture toughness. Ti-B grain refiner was added to further improve toughness through grain boundary strengthening mechanism. This research developed 5 vol.% ZrO₂ strengthened Al-10Zn-6Mg-2Si composite with addition of Al-5Ti-1B grain refiner produced through squeeze casting …

Defects And Deformation In Passive And Active Structural Glasses, Julia Ann Giannini

Dissertations - ALL

Glasses and disordered granular media represent a class of materials that are quite familiar to us, from the glass in windows and phone screens, to piles of fruits, grains, and sand. Further, living and active systems such as cellular tissues, collections of robots, and even human crowds behave as disordered solids when they are gathered at high enough densities. Despite their ubiquity, there are still many behaviors of these amorphous systems that lack a full understanding. Contrasting crystalline solids, the thermodynamic, vibrational, energetic, and mechanical properties of glasses are not well-characterized by solid state theory. In the case of active …

Encapsulated 2d Materials And The Potential For 1d Electrical Contacts, Sarah Wittenburg

Physics Undergraduate Honors Theses

The utilization of two-dimensional materials and heterostructures, particularly graphene and hexagonal boron nitride, have garnered significant attention in the realm of nanoelectronics due to their unique properties and versatile functionalities. This study focuses on the synthesis and fabrication processes of monolayer graphene encapsulated between layers of hBN, aiming to explore the potential of these heterostructures for various electronic applications. The encapsulation of graphene within hBN layers not only enhances device performance but also shields graphene from environmental contaminants, ensuring long-term stability. Experimental techniques, including mechanical exfoliation and stamp-assisted transfer, are employed to construct three-layer stacks comprising hBN-graphene-hBN. The fabrication process …

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 …

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 …

Magnetic Properties Of Zgnrs With Nitrogen And Fluorine Adsorbates, A Computational Study, Justin Petit

Electronic Theses and Dissertations

Imposing dimensional restrictions on graphene sheets and adding impurities can give rise to carbon nanostructures with magnetic properties. In this work, zigzag graphene nanoribbons, zGNRs, with nitrogen and fluorine adatoms are investigated for magnetic properties of interest for spin devices. Geometry optimizations were done determining which position along a zGNR electrode that N and F would favorably attach to. Edge positions were determined as the most stable attachment site. M-cell zGNR electrodes (M = 1-3) edge-functionalized by N and F adatoms were investigated with respect to their band structures and spin densities in antiferromagnetic and ferromagnetic, AFM and FM, configurations. …

First-Principles Studies Of Spin Transport And Spin-Orbit Torques, Giovanni Gabriel Báez Flores

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

This dissertation presents first-principles studies focusing on the effects of interfacial spin relaxation in metallic interfaces, interfacial intermixing on spin-orbit torques, and the effects of alloying on the transport properties of Fe|MgO|Fe magnetic tunnel junctions. Spin transport and spin-orbit torques are at the heart of phenomena in magnetic memory devices, such as tunnel magnetoresistance and magnetization switching. This work explores spin transport, spin-orbit coupling, spin-orbit torques, and tunneling magnetoresistance in a variety of materials and interfaces.

First discussed is the role of spin-orbit coupling at metallic interfaces by establishing a generalized magnetoelectronic circuit theory for normal metal (NM) interfaces, (NM|NM), …

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. …

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 …

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 …

Investigations Of Physical Properties Of Novel Magnetic And Non- Magnetic Two-Dimensional (2d) Alloys., Mohammed Ameen Irziqat

Electronic Theses and Dissertations

This research work reports investigations of structural and physical properties of novel magnetic and non-magnetic 2D alloys. Three techniques were utilized in this investigation: Angle-resolved polarized Raman spectroscopy (ARPRS), Electrical &Thermoelectric power measurements, Magneto-optic Kerr effect (MOKE) spectroscopy. ARPRS and MOKE experiments were constructed during the course of this work. ARPRS was used to study the anisotropy of 2-dimensional black-arsenic phosphors (b-AsxP1-x) as a function of arsenic concentration (x). It was observed experimentally that all Raman modes of the studied samples with x=0, 0.4, 0.8 exhibit polarization dependence. More interestingly, the polarization dependence of Raman modes due to the vibrations …

Gate-Controlled Supercurrent Effect In Dry-Etched Dayem Bridges Of Non-Centrosymmetric Niobium Rhenium, Jennifer Koch, Carla Cirillo, Sebastiano Battisti, Leon Ruf, Zahra Makhdoumi Kakhaki, Alessandro Paghi, Armen Gulian, Serafim Teknowijoyo, Giorgio De Simoni, Francesco Giazotto, Carmine Attanasio, Elke Scheer, Angelo Di Bernardo

Mathematics, Physics, and Computer Science Faculty Articles and Research

The application of a gate voltage to control the superconducting current flowing through a nanoscale superconducting constriction, named as gate-controlled supercurrent (GCS), has raised great interest for fundamental and technological reasons. To gain a deeper understanding of this effect and develop superconducting technologies based on it, the material and physical parameters crucial for the GCS effect must be identified. Top-down fabrication protocols should also be optimized to increase device scalability, although studies suggest that top-down fabricated devices are more resilient to show a GCS. Here, we investigate gated superconducting nanobridges made with a top-down fabrication process from thin films of …

Shorting At Long Duration: Impact Of Extended Discharge Capacity On Battery Solid Electrolytes, Ryan C. Hill, Amanda S. Peretti, Leo J. Small, Erik D. Spoerke, Yang-Tse Cheng

Chemical and Materials Engineering Faculty Publications

Long-duration energy storage (LDES) is critical to a stable, resilient, and decarbonized electric grid. While batteries are emerging as important LDES devices, extended, high-power discharges necessary for cost-competitive LDES present new materials challenges. Focusing on a new generation of low-temperature molten sodium batteries, we explore here unique phenomena related to long-duration discharge through a well-known solid electrolyte, NaSICON. Specifically, molten sodium symmetric cells at 110 ° C were cycled at 0.1 A cm−2 for 1–23 h discharges. Longer discharges led to unstable overpotentials, reduced resistances, and decreased electrolyte strength, caused by massive sodium penetration not observed in shorter duration discharges. …

Synthesis, Structural And Thermal Studies Of Dl-Alanine Potassium Di- Chromate Single Crystals, Sundararaj Lincy Mary Ponmani, Soundararajan Gnanakkan Pushpalatha Gracelin, Somasundaram Selvakumar, Subbaiah Chelladurai Vella Durai

Makara Journal of Science

Amino acids and their complexes are organic or semiorganic materials that have attracted considerable attention because they can be easily used in optical storage devices. DL-alanine is one of the rare amino acids that crystallizes in anoncentrosymmetric group. This article demonstrates how DL-alanine potassium dichromate (DAPC) single crystals have shown sufficient growth. DAPC crystals were analyzed by single crystal X-ray diffraction and powder X-ray diffraction. Using thermogravimetric analysis/differential thermal analysis (TGA/DTA) and differential scanning calorimetry, this work also examined the melting point, thermal stability, decomposition point, and other thermal parameters of the DAPC crystals. Results show that the decomposition point …

Interfacial Magnetism And Anisotropy In Dirac And Weyl Semimetals, Noah Schulz

USF Tampa Graduate Theses and Dissertations

Semimetals have gained intense interest recently due to their exotic magnetic and electronic properties. One of the most widely studied semimetals is graphene, a Dirac semimetal. The utilization of graphene in devices and sensors requires interfacing it with other materials, which may induce potentially strong interfacial effects. Furthermore, graphene alone does not possess magnetic order. Studying the interfacial effects between graphene and magnetic materials is therefore of great importance in the application of graphene to meet modern technological needs. Furthermore, by understanding the fundamental interfacial physics between graphene and magnetic materials, new properties can be unlocked, broadening the possible applications …

Machine Learning Prediction Of Photoluminescence In Mos2: Challenges In Data Acquisition And A Solution Via Improved Crystal Synthesis, Ethan Swonger, John Mann, Jared Horstmann, Daniel Yang

Seaver College Research And Scholarly Achievement Symposium

Transition metal dichalcogenides (TMDCs) like molybdenum disulfide (MoS2) possess unique electronic and optical properties, making them promising materials for nanotechnology. Photoluminescence (PL) is a key indicator of MoS2 crystal quality. This study aimed to develop a machine-learning model capable of predicting the peak PL wavelength of single MoS2 crystals based on micrograph analysis. Our limited ability to consistently synthesize high-quality MoS2 crystals hampered our ability to create a large set of training data. The project focus shifted towards improving MoS2 crystal synthesis to generate improved training data. We implemented a novel approach utilizing low-pressure chemical vapor deposition (LPCVD) combined with …