Physics Commons^™

Magnetic Properties And Ultrafast Spin Dynamics In Quantum Materials, Trung Kien Mac

All Graduate Theses and Dissertations, Fall 2023 to Present

Modern electronics mostly work by moving electric charge, which generates heat and hence wastes energy, especially as devices become smaller and faster. An alternative is to use the spin of electrons (a tiny magnetic property) and related “valley” states in certain atomically thin materials to store and process information more efficiently. This thesis explores how magnetism and spin behavior can be created and measured in a family of ultra-thin materials known as van der Waals quantum materials. Three kinds of materials are studied. First, atomically thin semiconductors are shaped into narrow nanoribbons. Because of their narrow size, their edges can …

Mining Time Series Shapelets And Association Rules For Solar Flare Prediction, Drew Watson

All Graduate Theses and Dissertations, Fall 2023 to Present

Solar flares are the largest explosions in the solar system; they are caused by changes in the Sun’s magnetic field. Strong solar flares can disrupt power systems, damage satellites, and interfere with radio communication, so improving flare prediction is important. This thesis develops a way to predict severe solar flares while also helping researchers understand why those predictions are made. The approach looks for short patterns in solar magnetic field data that are linked to future flare activity. It then studies how these patterns appear together and in what order they happen over time. By doing this, the research not …

Hidden Symmetries And Higher Dimensional Rotating Black Holes, Luis Fernando Temoche Hurtado

All Graduate Theses and Dissertations, Fall 2023 to Present

A standard approach to probing the dynamics of a physical system is to expose it to an external perturbation—such as an incident wave—and analyze its response after the interaction. Mathematically, this procedure is formulated in terms of differential equations governing the evolution of the perturbation.

In the context of black hole physics, an analogous strategy can be employed by studying the response of the event horizon to external perturbations. The differential equations describing these interactions are often invariant under nontrivial transformations, revealing hidden symmetries that help explain distinctive features of higher-dimensional black holes.

By exploiting these hidden symmetries in the …

Visualizing The Phase Space Of Two Interacting Spherical Magnets Via Lagrangian Descriptors, Matthew Pontius

All Graduate Theses and Dissertations, Fall 2023 to Present

This thesis studies the motion of one spherical magnet sliding on another fixed spherical magnet. Although the setup is simple, the resulting motion can range from regular and predictable to chaotic as the energy increases. To understand this behavior, mathematical tools are used to visualize how all possible motions are organized in phase space. These methods reveal patterns such as stable regions, repeating motions, and chaotic trajectories. The results show how order and chaos coexist in this system and provide insight into how small changes in the initial conditions can lead to very different outcomes.

We Can Track Waves In The Atmosphere From The Bear Lake Observatory And The International Space Station, Connor Waite

Research on Capitol Hill

Both space weather and tropospheric weather can create waves in Earth’s atmosphere called traveling ionospheric disturbances (TIDs) that can: 

• Disrupt GPS navigation by several meters 
• Cause radio blackouts affecting aviation and emergency services 
• Interfere with satellite communications 
• Impact the growing space industry 

A New Tool Predicts The Risk Of Surface Damage And Subsequent Spacecraft Charging, Trace Taylor, Ashley Bahora

Research on Capitol Hill

We measured secondary electron yield (SEY), a key factor in spacecraft charging, across multiple materials under different surface conditions. SEY is a measure of how many electrons a surface releases when hit by radiation.

Development Of A High-Doppler Shift Optical Simulator To Test Femtosecond-Level Optical Time-Frequency Transfer, Matthew S. Bigelow, Kyle W. Martin, Nolan Matthews, Benjamin K. Stuhl, Richard Gonzales, Alexandre De Pinho E Braga, John Elgin, Kimberly A. Frey

Space Dynamics Laboratory Publications

We have developed an optical simulator to test real-time optical two-way time–frequency transfer at the femtosecond level capable of simulating relative motion between two linked optical clock nodes up to Mach 1.8 with no moving parts. The technique is enabled by artificially Doppler shifting femtosecond pulses from auxiliary stabilized optical frequency combs. These pulses are exchanged between the nodes to simulate the Doppler shifts observed from a changing optical path length. We can continuously scan the simulated velocity from 14 to 620 m s⁻¹ while simultaneously measuring velocity-dependent clock shifts at much higher velocities than previously recorded. This system …

Tidal Interactions In Strong Field Gravity, Maria Jose Rodriguez

Funded Research Records

No abstract provided.

Exceptional Holography, Oscar Varela

Funded Research Records

No abstract provided.

Modulation Of The Semi-Annual Oscillation By Stratospheric Sudden Warmings As Seen In The High-Altitude Jawara Re-Analyses, Jiarong Zhang, Yvan Orsolini, Kaoru Sato

All Physics Faculty Publications

The semi-annual oscillation (SAO) dominates seasonal variability in the equatorial stratosphere and mesosphere. However, the seasonally dependent modulation of the SAO in the stratosphere (SSAO) and mesosphere (MSAO) by sudden stratospheric warmings (SSWs) in the Arctic has not been investigated in detail. In this study, we examine the seasonal evolution of the SAO during 16 major SSW events spanning 2004 to 2024 using the Japanese Atmospheric General Circulation Model for Upper Atmosphere Research Data Assimilation System Whole Neutral Atmosphere Re-analysis (JAWARA). Basic features of the SAO are well captured by JAWARA, as evidenced by the SSAO and MSAO appearing at …

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

Journal Articles

Spacecraft charging issues are often investigated with simulated space environments and evaluated on pass–fail criteria that may yield little or no information about materials’ properties. It is far more effective to understand and mitigate spacecraft charging issues through investigations of material properties. However, material properties are dynamic in the harsh environment of space. Approximations must be made to simulate the space environment in the laboratory. This article reports on the investigation of the approximation that energy deposition causes the same aging effects in materials irrespective of the type of radiation sources. Samples of polytetrafluoroethylene (PTFE) and polyether-etherketone (PEEK) were irradiated …

Effect Of Space Radiation On The Mechanical Properties Of High-Strength Polyethylene Nanocomposite Films, Seunghyun Moon, Achal Duhoon, Zhongtian Gu, Jr Dennison, Tengfei Luo

Journal Articles

This study experimentally investigates the effects of prolonged radiation exposure on mechanical properties of high-strength, highly crystalline polyethylene (PE)/thermally reduced graphene oxide (TrGO) nanocomposite films for space applications. Prior to irradiation, PE/TrGO films were found to have tensile strengths up to ~4 GPa, more than 40 times that of conventional space-deployed membrane films (e.g., those used in solar sails) and over 59× the specific tensile strength. The PE/TrGO films were subjected to three radiation conditions to simulate space environmental conditions: ⁹⁰Sr beta radiation (0.2 to 2.5 MeV), 80 keV electron beam irradiation, and 4.9 eV ultraviolet (254 nm) exposure. …

Electron Yields Of Lunar Regolith Simulant Layers, Christopher Vega, Matthew Robertson, Thomas Keaton, Heather Allen, Jr Dennison

Journal Articles

The charging of bulk lunar regolith has been recognized since the Apollo era as an immediate and critical issue facing our return to the moon. Accurate electron yield (EY) measurements of bulk highly insulating granular materials—which largely determine how such particles charge through interactions with space environments—are lacking due to many experimental complexities that have led to a critical knowledge gap. Such knowledge is essential for addressing fundamental science and myriad important lunar applications and simulations related to lunar dust and regolith electrostatic charging. The few prior EY studies of lunar dust were limited due to severe charging effects and …

Time-Dependent Radiation Induced Conductivity Of Polyimide: Effects Of Dose Rate And Temperature On Dynamic Ric, Tyler Heggenes, Jenny R. Whiteley, Jodie Gillespie, Jr Dennison

Journal Articles

Radiation induced conductivity (RIC) can impact charge dissipation within highly insulating materials used in spacecraft in harsh space plasma environments. Previous Utah State University (USU) research analyzed only the equilibrium portions of an extensive RIC database for polymeric materials, including Kapton HN (Trademark). This confirmed that equilibrium RIC follows a standard theoretical model that is temperature and dose rate dependent. The current study provides a new analysis of RIC’s time-dependent behavior of the Kapton HN data from this database. With the onset of radiation, the material response is characterized by an exponential increase in conductivity, while a hyperbolic inverse time-dependent …

Analytical Solutions For Transitional Flow Around Hydrometeors: Implications For Particle Dynamics And Atmospheric Modeling, Ahmad Talaei, Timothy J. Garrett

Physics Student Research

Accurate modeling of hydrometeor dynamics is critical for advancing weather and climate predictions. However, this remains a long-standing challenge in atmospheric science, particularly within the transitional Reynolds number regime, due to the lack of analytical solutions to the Navier–Stokes equations. This study presents two analytical solutions for two-dimensional, incompressible, and viscous flow around a sphere, addressing the gap between low and high Reynolds number regimes. The first framework, an extension of classical expansion methods using hypergeometric, provides a direct analytical relation that characterizes separation angle across the transitional regime. To address post- separation dynamics, a second formulation based on a …

Eng- Semicon: Understanding Nanoscale Heat Transport In Wide- And Ultrawide Bandgap Semiconductors Using Novel Deep Ultraviolet Tools, Joshua Lee Knobloch

Funded Research Records

No abstract provided.

Time-Evolved Constant Voltage Conductivity Measurements Of Common Spaceborne Polymeric Materials, Brian Wood, David King, Jr Dennison

Journal Articles

Long-duration current measurements were made for low-density polyethylene (LDPE), polyimide (PI), polyether ether ketone (PEEK), and biaxially oriented polypropylene (BOPP) to determine their bulk conductivity near room temperature as a function of time. These common thin-film spacecraft material samples were vacuum baked to remove moisture and volatile contaminants to better simulate space conditions. The constant voltage conductivity (CVC) method used a very stable, low-noise dc voltage source and measured the resulting current in a parallel plate geometry. Due to the extremely low conductivity of these four polymeric materials, extended experiments of up to ten days were necessary to establish equilibrium …

An Investigation Into The Principle Of Symmetric Criticality, Guillermo Frausto

All Graduate Theses and Dissertations, Fall 2023 to Present

In physics, symmetries help us understand complex systems by revealing conserved quantities and simplifying equations. In the context of general relativity, where spacetime is curved and dynamic, these symmetries become especially important when trying to reduce or solve the equations that govern gravitational and matter fields.

This dissertation investigates a mathematical principle known as the Principle of Symmetric Criticality (PSC), which helps determine when symmetries can be used to simplify physical theories without losing essential information. While often assumed to be valid, PSC does not always hold, and understanding when it does is critical for the reliable use of symmetry …

Revised Unsteady Drag Force And Its Impact On Particle Dynamics At High Reynolds Numbers, Ahmad Talaei, Timothy J. Garrett

Physics Student Research

The accurate modeling of particle motion in viscous fluids at high Reynolds numbers remains a fundamental challenge, particularly under unsteady flow conditions where nonlinear effects dominate. This study introduces a revised unsteady drag formulation, extending its applicability beyond previous studies. By integrating classical solutions of the Navier–Stokes equations, the new formulation overcomes the limitations of the Maxey–Riley–Gatignol (MRG) equation, addressing non-physical memory effects associated with Basset drag and extending its applicability to higher Reynolds numbers.

Through experimental comparisons and direct numerical simulations (DNS), the revised equation of motion is compared to the MRG equation, both during steady-state conditions and non-equilibrium …

Enhancing Stability And Emissions In Metal Halide Perovskite Nanocrystals Through Mn2+ Doping, Thi Thu Trinh Phan, Thi Thuy Kieu Nguyen, Trung Kien Mac, Minh Tuan Trinh

Chemistry and Biochemistry Student Research

Metal halide perovskite (MHP) nanocrystals (NCs) offer great potential for high-efficiency optoelectronic devices; however, they suffer from structural softness and chemical instability. Doping MHP NCs can overcome this issue. In this work, we synthesize Mn-doped methylammonium lead bromide (MAPbBr₃) NCs using the ligand-assisted reprecipitation method and investigate their structural and optical stability. X-ray diffraction confirms Mn²⁺ substitution at Pb²⁺ sites and lattice contraction. Photoluminescence (PL) measurements show a blue shift, significant PL quantum yield enhancement, reaching 72% at 17% Mn²⁺ doping, and a 34% increase compared to undoped samples, attributed to effective defect passivation and …

Comparison Of Gravity Waves Observed By Atmospheric Waves Experiment (Awe) And Simulated By High-Resolution Waccm-X, Jiarong Zhang, Han-Li Liu, Yucheng Zhao, Dominique Pautet, Ludger Scherliess, Michael Taylor

Space Dynamics Laboratory Publications

Outline

Data: AWE and High-Resolution Whole Atmosphere Community Climate Model with thermosphere and ionosphere extension (HR-WACCMX) simulation

• Quantify gravity wave (GW) activity
• Compare GW activity observed by AWE and simulated by high-resolution WACCMX
• GW activity over Western Europe

Geometric Algebra For Field Theory In Curved Spacetime, Kevin Rhine

All Graduate Reports and Creative Projects, Fall 2023 to Present

Physics seeks to understand the universe by uncovering the fundamental laws that govern matter, energy, space, and time. At its heart lies the challenge of unification: finding a mathematical framework that consistently describes these interactions across all scales, from the subatomic to the cosmological.

This thesis explores geometric algebra, a mathematical language that unifies algebra and geometry, as a tool for advancing this understanding. By extending this framework to curved spacetimes, where gravity influences the structure of space and time, we investigate its ability to describe physical phenomena such as electromagnetism and general relativity. A notable contribution includes the geometric …

Gravity Wave Breaking Over Northern Utah With An Advanced Mesospheric Temperature Mapper And Sodium Lidar, Eric Davis

All Graduate Reports and Creative Projects, Fall 2023 to Present

Considerable progress has been made in recent decades in the understanding of gravity wave (GW) dynamics. However, there remain important aspects and effects that are poorly understood. In particular, the coupling and deposition of their energy and momentum into the mesosphere lower thermosphere (MLT) region and the interaction and instability dynamics that are directly associated with GW breaking. Using an Advanced Mesosphere Temperature Mapper (AMTM) several strong wave breaking events were observed in the summer of 2015 at USU’s BLO research station. These events have exhibited high momentum fluxes and associated strong wave breaking, prompting detailed data analyses. Rossby waves, …

Conservation Laws For Asymptotically Perfect Fluid Spacetimes, Lyle Arnett Jr.

All Graduate Theses and Dissertations, Fall 2023 to Present

In physics, conservation laws, like those for energy or momentum, are powerful tools that help us understand how systems evolve and interact. In general relativity, where spacetime itself is curved by matter and energy, defining such conservation laws becomes especially subtle and complex. Traditional methods rely on idealized conditions like empty space or special symmetries, which limit their usefulness in more realistic, dynamic settings such as an expanding universe.

This dissertation explores a modern mathematical framework, developed by Iyer and Wald, that allows conservation laws to be derived directly from the equations governing spacetime. Using this approach, I examine not …

Measuring Small Currents At Fast Speeds Using A 2nd Generation Electrometer, Donna Metcalf

Physics Capstone Projects

This project presents the development of a second-generation electrometer designed to measure extremely low currents with improved speed and sensitivity. Based on the foundational architecture developed by Vladimir Zavylov, this iteration focuses on enhancing performance through optimized circuit components, modular configuration, and a custom-designed, battery- powered power supply that enables high-voltage floating measurements. The work encompasses the complete design cycle—creating a full schematic, developing a tailored power delivery system, assembling printed circuit boards (PCBs), constructing wiring harnesses, and integrating components into a protective housing.

Young Professionals, Zachary Gibson

Journal Articles

Like many of us, I have attended numerous panels, seminars, and workshops geared toward helping young professionals and students. The more senior professionals are gathered for us to question and tap them for wisdom and anecdotes. One such question that inevitably comes up in one form or another is, “How did you get to where you are?” A thinly veiled question intending to ask how can one get to the same or similar position. The response often begins with a soft chuckle and a “well … ” Their answers are caveated by “my path was not the typical path.”

Measuring Small Currents At Fast Speeds Using A 2Nd Generation Electrometer, Donna Metcalf

Student Research Symposium

The Electron Emission Test (EET) chamber in the Utah State University Materials Physics Group (MPG) is used to determine the electron yield of highly insulating materials. An electrometer is employed alongside the EET chamber to measure the output current of 10-6 to 10-14 pulses of 10-7 seconds to DC duration. In previous years, a first- generation electrometer was used for these measurements. However, the introduction of a new electrometer presents an opportunity to achieve faster measurement speeds and improved sensitivity to smaller current values.

Effect Of Geomagnetic Activity On Radio Propagation In The 14 And 18 Mhz Range, Stuart Barney

Student Research Symposium

The purpose of this experiment was to discover if the magnitude of a geomagnetic event has a notable effect on the reliability of the reception of a radio transmission given the location of origin.

Automatic Aurora Detection, Cameron Eggleston

Student Research Symposium

Aurorae happen when particles in the earth’s magnetosphere become excited and emit visible light. Below is a picture that shows this process more meaningfully:

The colors of each aurora is determined by these electrons as well. Below is a diagram showing where the different colors of aurora come from. In addition to being nice to look at, aurorae can be caused by Coronal Mass Ejections(CMEs). CMEs can affect radio communication, power grids, GPS systems, and more.

2017 Seasonal Variation Of Atmospheric Gravity Waves Above Rothera Station, Antarctica, Elijah Kroeber, Zhao Yucheng, Pautet Dominique, Taylor Michael

Student Research Symposium

As a part of the international Antarctic Gravity Wave Instrument Network (ANGWIN), Utah State University operates an infrared (IR) all-sky imager at the British Rothera Station in Antarctica (67°34’S, 68°07’W) which observes several hydroxyl (OH) emission bands.