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Articles 1 - 30 of 1922

Full-Text Articles in Condensed Matter Physics

Exploring Red Palm Oil As A Sustainable Plasticizer For Carbon Black-Filled Ssbr/Br Tire Tread Compounds: A Comparative Evaluation Of Commercial Alternatives, Norma Arisanti Kinasih, Mohamad Irfan Fathurrohman, Santi Puspitasari, Dewi Kusuma Arti, Abdulhakim Masa Aug 2026

Exploring Red Palm Oil As A Sustainable Plasticizer For Carbon Black-Filled Ssbr/Br Tire Tread Compounds: A Comparative Evaluation Of Commercial Alternatives, Norma Arisanti Kinasih, Mohamad Irfan Fathurrohman, Santi Puspitasari, Dewi Kusuma Arti, Abdulhakim Masa

Journal of Materials Exploration and Findings

This study investigates the application of red palm oil (RPO) as an alternative vegetable oil resource to substitute petroleum-based plasticizers, which have environmental and health concerns, in carbon black (CB)-filled SSBR/BR tire tread compounds. The plasticizing effects of RPO were thoroughly evaluated by comparing them with a commercial bio-based plasticizer, Epoxidized Soybean Oil (ESBO), and two safer petroleum-based oils, Naphthenic Oil (NYNAS) and Treated Distillate Aromatic Extract (TDAE). The initial investigation shows that fatty acid composition is imposing regarding the plasticizing effect. The higher unsaturated fatty acid content in RPO than in ESBO improved tensile strength and degraded rolling resistance …


Metallurgical Investigation Of A Modified Eye Bolt Failure Caused By Improper Weld Extension, Specification Deviation, And Crevice Corrosion, Dimas Muhammad Fawwaz, Reza Miftahul Ulum, Johny Wahyuadi Soedarsono, Yudha Pratesa Aug 2026

Metallurgical Investigation Of A Modified Eye Bolt Failure Caused By Improper Weld Extension, Specification Deviation, And Crevice Corrosion, Dimas Muhammad Fawwaz, Reza Miftahul Ulum, Johny Wahyuadi Soedarsono, Yudha Pratesa

Journal of Materials Exploration and Findings

A modified eye bolt from the David Arm Manhole Storage Tank underwent thorough metallurgical study due to the consequences of the bolt's malfunction during operation. Safety issues arose when the manhole door detached during operation. The mechanical testing and chemical composition analysis of the bolts indicated they were manufactured from an ASTM A193 Grade B7 material used for high-temperature bolting. This material did not conform to the engineering drawing, which mentioned SA 563A, which is about nuts, not bolts. This contradiction clearly shows that the eye bolt which was installed does not conform to the intended design. Welded connections of …


Rejection Of Fe (Iron) And Kmno4 (Organic Substance) Parameters In Peat Water Using Organic Membranes, Muhamad Rafli Sakti Mulia Gonera, Siti Umi Kalsum, Sarah Fiebrina Heraningsih Aug 2026

Rejection Of Fe (Iron) And Kmno4 (Organic Substance) Parameters In Peat Water Using Organic Membranes, Muhamad Rafli Sakti Mulia Gonera, Siti Umi Kalsum, Sarah Fiebrina Heraningsih

Journal of Materials Exploration and Findings

Peat water is a surface water source widely used by people in swampy and lowland areas, but it has poor quality characteristics such as high organic matter content, low pH, and dissolved metal levels such as iron that exceed the threshold. These conditions can cause health problems and reduce the quality of clean water so that effective treatment technology is needed. This study aims to analyze the effectiveness of ultrafiltration membranes made from chitosan from shrimp shell waste in rejecting iron (Fe) and organic substances in peat water, and to determine the effect of pressure on separation performance. This study …


Synthesis And Characterization Of Carbon Quantum Dots And Gold Nanoparticles For Norovirus Biosensing Applications In Water Systems, Breanne Evans Aug 2026

Synthesis And Characterization Of Carbon Quantum Dots And Gold Nanoparticles For Norovirus Biosensing Applications In Water Systems, Breanne Evans

Master's Theses

Rapid, reliable detection of viral pathogens remains a significant challenge across water-treatment and environmental monitoring systems, including drinking-water, wastewater, water reuse, and environmental surveillance applications. Waterborne viral contamination can pose substantial public-health risks, making early detection essential for protecting water quality and responding quickly to treatment failures or contamination events. Direct potable reuse (DPR) is one particularly demanding example because it requires continuous verification of treatment performance and the broader need for rapid virus monitoring extends across many water-treatment and environmental surveillance applications. Norovirus is a priority target because of its widespread occurrence in wastewater, environmental persistence, and exceptionally low …


Glassy Magnetic Freezing Of Interacting Clusters In Materials Related To The Lk-99 Family, Serafim Teknowijoyo, Domenico Napoletani, Vahan Nikoghosyan, Armen Gulian Jul 2026

Glassy Magnetic Freezing Of Interacting Clusters In Materials Related To The Lk-99 Family, Serafim Teknowijoyo, Domenico Napoletani, Vahan Nikoghosyan, Armen Gulian

Mathematics, Physics, and Computer Science Faculty Articles and Research

We report reproducible magnetization anomalies appearing below room temperature in copper-doped apatite materials belonging to the LK-99 family synthesized via hydrothermal methods. These anomalies are observed consistently across samples prepared under comparable conditions. Although the extracted Mydosh parameter lies within the range often associated with vortex-glass behavior in superconductors, a detailed analysis of DC magnetization, AC susceptibility, field dependence, and magnetic memory effects demonstrates that the observed phenomena are not related to superconductivity. Instead, the data are consistent with glassy magnetic freezing of interacting clusters. Compositional and structural analysis identifies covellite (CuS), one of the constituent phases in these multiphase …


The Role Of Zinc Precursor Concentration In Modulating The Structural, Optical, And Electrical Properties Of Sol-Gel Derived Czts Thin Films, Justine John Tibaijuka Jun 2026

The Role Of Zinc Precursor Concentration In Modulating The Structural, Optical, And Electrical Properties Of Sol-Gel Derived Czts Thin Films, Justine John Tibaijuka

Tanzania Journal of Science

This study reports on CZTS thin films fabricated by sol–gel spin coating using zinc acetate dihydrate, copper acetate dihydrate, tin chloride, and thiourea dissolved in methanol with monoethylamine as a stabilizer. The films were annealed rapidly at 540 °C by using an RTP furnace. Results show the significant influence of zinc concentration on films’ properties with band gap evolution between 1.46 and 1.7 eV, along with high absorption coefficients exceeding 10⁴ cm⁻¹ in the visible range. Structurally, the films evolved from poorly crystalline at low Zn content to well- crystallized, (112)-oriented kesterite near stoichiometry. However, excessive Zn caused slight degradation …


Phenomenological Dynamical Mean-Field Theory Of Temperature-Dependent Optical Conductivity And Metal-Insulator Transition In La0.7ca0.3mno3, Listiana Satiawati, Adam Badra Cahaya, Eddwi Hesky Hasdeo, Muhammad Aziz Majidi, Anto Sulaksono, Andrivo Rusydi Jun 2026

Phenomenological Dynamical Mean-Field Theory Of Temperature-Dependent Optical Conductivity And Metal-Insulator Transition In La0.7ca0.3mno3, Listiana Satiawati, Adam Badra Cahaya, Eddwi Hesky Hasdeo, Muhammad Aziz Majidi, Anto Sulaksono, Andrivo Rusydi

Makara Journal of Science

As an extension of our previous theoretical study, we perform temperature-dependent optical conductivity calculations on La0.7Ca0.3MnO3 over a wide photon-energy range up to ∼22 eV, aiming to capture the metal–insulator transition while preserving the general temperature-dependent profile at higher photon energies. The system is modeled with simple Mn–O coordination via the tight-binding method, where some hopping integrals are considered functions of magnetization. Upon incorporating the static Jahn–Teller effect with Coulomb–Hubbard and magnetic exchange interactions, with the exception of a quantitative difference in the calculated of  K versus the experimental value (260 K) and discrepancies in …


Lafe0.925ti0.075o3 Perovskite Coated With Ethyl Cellulose: A High-Stability, Low-Hysteresis Platform For Advanced Humidity Sensing, Akhmad Futukhillah Fataba Alaih, Djoko Triyono, Rifqi Almusawi Rafsanjani Jun 2026

Lafe0.925ti0.075o3 Perovskite Coated With Ethyl Cellulose: A High-Stability, Low-Hysteresis Platform For Advanced Humidity Sensing, Akhmad Futukhillah Fataba Alaih, Djoko Triyono, Rifqi Almusawi Rafsanjani

Makara Journal of Science

Humidity sensors are pivotal in numerous sectors, such as environmental monitoring, industrial automation, and health-care. This study presents the fabrication and detailed evaluation of an advanced humidity sensor using ethyl cellulose (EC)-coated LaFe0.925Ti0.075O3 (LFTO) perovskite nanoparticles synthesized via the sol-gel method. The LFTO nanopar-ticles exhibited a mesoporous structure with an enhanced surface area, which significantly improved their moisture adsorption capabilities. The innovative application of EC coating addresses critical substrate adhesion issues, enhancing mechanical stability without compromising sensor sensitivity. Comprehensive performance evaluations revealed minimal hysteresis (


Fabrication Of Two-Dimensional Optoelectrical Devices, Holly Walworth Jun 2026

Fabrication Of Two-Dimensional Optoelectrical Devices, Holly Walworth

Honors Projects

Optoelectrical devices enable the exploration of interesting quantum states observed in two-dimensional (2D) condensed material systems. 2D materials, such as graphene and transition metal dichalcogenides, exhibit unique electronic properties, including the Fractional Quantum Anomalous Hall effect (FQAHE). The realization of the FQAHE offers a pathway toward topological quantum computing via non-Abelian anyons. Still, fabricating high-quality 2D optoelectrical devices remains a significant experimental challenge. Using mechanical exfoliation and stacking techniques within an inert argon environment, we attempted to fabricate optoelectrical devices using twisted molybdenum ditelluride (tMoTe2) and gallium telluride (GaTe). Three devices were successfully assembled; however, structural defects including hexagonal boron …


Momentum Space Algorithm For Electronic Structure Of Double-Incommensurate Trilayer Graphene, Kenneth Silver Beard May 2026

Momentum Space Algorithm For Electronic Structure Of Double-Incommensurate Trilayer Graphene, Kenneth Silver Beard

LSU Doctoral Dissertations

Numerical algorithms for computing the electronic structure of incommensurate 2D-materials using ab initio models are critical for predicting material properties and guiding experiments. For bilayers, momentum space and continuum models have been introduced to approximate observables of ab initio tight-binding models using a momentum description, despite the lack of periodicity in the tight-binding model required for Bloch theory. A similar structure has been introduced for double-incommensurate trilayers using a continuum model, where the three lattices are mutually incommensurate. However, this description leads to a four-dimensional lattice space, and numerical convergence of the density of states has been observed to be …


Designing Enhanced Nonlinearity In Plasmonic Devices With Epsilon-Near-Zero Films, Kevin Tran Le May 2026

Designing Enhanced Nonlinearity In Plasmonic Devices With Epsilon-Near-Zero Films, Kevin Tran Le

Electrical Engineering and Computer Science (MS) Theses

The growing demand for energy-efficient optical information processing motivates compact nonlinear photonic devices that can operate at low power. Silicon photonics is a mature platform for linear optical functions, but nonlinear operation remains challenging because of its weak Kerr response, two-photon absorption at telecommunication wavelengths, and limited compatibility with deeply subwavelength plasmonic confinement. This thesis computationally investigates epsilon-near-zero thin films integrated into plasmonic waveguide architectures as a route toward stronger light–matter interaction in compact nonlinear devices.

Two waveguide geometries are examined: a hybrid metal-insulator-metal plasmonic slab waveguide incorporating an ultrathin indium tin oxide epsilon-near-zero layer (5–50 nm), and a dielectric-loaded …


Strain Engineering Of Excitonic And Vibrational Properties In Two-Dimensional Transition Metal Dichalcogenides, Sneha Minesh Patel May 2026

Strain Engineering Of Excitonic And Vibrational Properties In Two-Dimensional Transition Metal Dichalcogenides, Sneha Minesh Patel

Graduate Theses and Dissertations

Mechanical strain represents a robust and non-invasive method for tuning the electronic and vibrational properties of two-dimensional transition-metal dichalcogenides (TMDs). This work examines homogeneous biaxial strain as a symmetry-preserving control parameter that governs excitonic and interlayer dynamics in atomically thin TMDs. In monolayer MoSe2, biaxial tensile strain is intrinsically generated during high-temperature physical vapor deposition due to thermal expansion mismatch with amorphous substrates. Optical spectroscopy demonstrates substantial and tunable excitonic energy shifts exceeding 100 meV per percent strain. Polarization-resolved second harmonic generation confirms the retention of lattice symmetry under biaxial deformation. The investigation is further extended to bilayer MoS2, where …


Structural Relaxation In Glass-Forming Liquids At Extreme Pressure: Photon-Correlation Spectroscopy And Constrained Thermodynamic Surface Modeling, Kevin Wayne Lyon May 2026

Structural Relaxation In Glass-Forming Liquids At Extreme Pressure: Photon-Correlation Spectroscopy And Constrained Thermodynamic Surface Modeling, Kevin Wayne Lyon

Graduate Theses and Dissertations

Structural relaxation in glass-forming liquids is strongly dependent on both temperature and pressure, yet direct measurement of structural α-relaxation under multi-gigapascal compression has remained experimentally challenging. This work extends depolarized photon correlation spectroscopy (DPCS) to pressures approaching 5 GPa in a diamond anvil cell, representing the highest-pressure implementation of this technique and enabling direct measurement of the structural α-relaxation in a pure liquid at extreme compression. This capability provides access to dynamical regimes previously unexplored by photon correlation spectroscopy and establishes a platform for probing glassy dynamics at high pressure. To describe these measurements, a constrained relaxation-time surface framework is …


Exactly Solving One-Dimensional Models For The Fractional Quantum Hall Effect, Joseph R. Cruise Apr 2026

Exactly Solving One-Dimensional Models For The Fractional Quantum Hall Effect, Joseph R. Cruise

Arts & Sciences Graduate Student Theses and Dissertations

Nearly fifty years after its experimental debut, the quantum hall effect has produced perhaps more unique descriptions than any other subject of condensed matter physics. From topological band theory to non-commutative geometry, topological and conformal field theories, random matrix models and more, each approach captures a subset of the essential features, and compliments the others to produce a beautiful mosaic description. In this thesis, we revisit the fractional quantum hall (FQH) effect from its oldest vantage point, that of the trial wavefunctions and the parent Hamiltonians which stabilize them. Laughlin's observation of the importance of the theory of holomorphic functions …


The Role Of Interactions In Moiré Quantum Materials, Liangtao Peng Apr 2026

The Role Of Interactions In Moiré Quantum Materials, Liangtao Peng

Arts & Sciences Graduate Student Theses and Dissertations

Moiré quantum materials have emerged as a highly tunable platform for studying strongly interacting electrons in low dimensions. By twisting or lattice-mismatching atomically thin crystals, one can generate long-wavelength moiré superlattices that reconstruct the electronic bands, produce narrow bandwidths, and greatly enhance the importance of Coulomb interactions. As a result, these systems host a wide range of correlated phenomena, including symmetry breaking, magnetism, and superconductivity. This dissertation develops and applies Green's-function-based many-body methods to understand the role of interactions in moiré quantum materials. This dissertation consists of four chapters. The first chapter introduces moiré quantum materials and reviews the basic …


3Ω Thermal Transport In Atomically Thin Materials, Yiwei Le Apr 2026

3Ω Thermal Transport In Atomically Thin Materials, Yiwei Le

Arts & Sciences Graduate Student Theses and Dissertations

Since the discovery of graphene, research on two-dimensional (2D) materials has become a central focus of condensed matter physics. While an enormous number and variety of investigations of their electrical, optical, and mechanical properties have been undertaken, their thermal properties remain comparatively underexplored, despite the importance for understanding low-energy excitations and phase transitions. Here, we introduce an extension of the 3ω method thermal measurement technique to the 2D limit of materials. We develop analytical models of thermal transport in the 3ω geometry with boundary conditions tailored for suspended 2D flakes. We then experimentally confirm the feasibility of this approach in …


Electron Emission From Unactivated Gaas: Towards The Development Of Novel Sources Of Spin-Polarized Electrons, William Truslow Newman Apr 2026

Electron Emission From Unactivated Gaas: Towards The Development Of Novel Sources Of Spin-Polarized Electrons, William Truslow Newman

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

Spin-polarized electrons are commonly emitted from GaAs photocathodes with treated surfaces in a process called negative electron affinity activation. These sources require stringent vacuum conditions that are often hard to achieve and lead to significant downtimes in experiments. In this dissertation, I present new investigations of electron emission from unactivated GaAs towards the development of novel sources of spin-polarized electrons. The work entails two primary directions. The first is the investigation of electron emission using multiphoton ionization processes enhanced by nanoscale surface structures. We explore GaAs electron sources including, shards, nanotip arrays of pyramid structures, wedges, and ion-milled tips. The …


Feasibility Analysis Of Thermal Oxidizer To Determine Remaining Life Using Fitness- For-Service Level 3 Method, Yudhi Yudistirawan, Donanta Dhaneswara, Wahyuaji Narottama Putra, Gama Widyaputra, Dewi Kurnia Suci, Agung Putra Mahardhika Apr 2026

Feasibility Analysis Of Thermal Oxidizer To Determine Remaining Life Using Fitness- For-Service Level 3 Method, Yudhi Yudistirawan, Donanta Dhaneswara, Wahyuaji Narottama Putra, Gama Widyaputra, Dewi Kurnia Suci, Agung Putra Mahardhika

Journal of Materials Exploration and Findings

An aged thermal oxidizer (TOX) in the oil and gas industry necessitates a comprehensive evaluation to ensure its continued safe operation. This study presents a Remaining Life Assessment (RLA) and a Fitness for Service (FFS) evaluation for the four main components of the TOX, in accordance with API 510, API 579/ASME FFS-1, and ASME BPVC Section VIII Div-1 standards. The investigation includes the determination of maximum stress and maximum temperature required to assess the operational viability of the reactor. The four components are radiant, convection, transition, and stack sections—were modeled using the finite element method (FEM). Following the geometric modeling, …


Assessing Passenger Electric Vehicle Growth Strategies And Their Impacts On Electricity Demand Load And Co2 Emissions In Aceh Province To Achieve Net Zero Emission Target By 2060, Taufik Hidayat, Widodo Wahyu Purwanto Apr 2026

Assessing Passenger Electric Vehicle Growth Strategies And Their Impacts On Electricity Demand Load And Co2 Emissions In Aceh Province To Achieve Net Zero Emission Target By 2060, Taufik Hidayat, Widodo Wahyu Purwanto

Journal of Materials Exploration and Findings

The electrification of the transport sector is a crucial pathway for achieving Indonesia’s Net Zero Emissions (NZE) target by 2060. This study assesses the potential impact of passenger electric vehicle (EV) penetration on electricity demand and CO2 emissions in Aceh Province through a scenario-based modelling approach. Two policy-aligned scenarios are assessed: a low-penetration (LP) scenario and a high-penetration (HP) scenario. Using the Gompertz model and the ASIF framework, total CO2 emissions were projected from 2020 to 2060. Results show that although higher EV penetration reduces direct emissions from internal combustion engine (ICE) vehicles, total CO2 emissions increase more significantly under …


Developing A Workforce To Build A Star On Earth, Vola Andrianarijaona, Angelina Castillo, Sean Walters Apr 2026

Developing A Workforce To Build A Star On Earth, Vola Andrianarijaona, Angelina Castillo, Sean Walters

Campus Research Month

This study is meant to help understand why fusion has remained "30 years away" for decades and why that may finally be changing.We see nuclear fusion not merely as a physics phenomenon, but as a complex engineering challenge requiring coordination across different disciplines, including physics, materials science, electrical and mechanical engineering, systems engineering, robotics, and computer science, etc. Indeed, nuclear fusion is not just about "making atoms fuse"—it's about controlling, powering, measuring, and stabilizing one of the most extreme environments humans have ever built. Advances in superconducting magnets, new materials are bringing fusion closer to reality than ever before, and …


Harnessing Wavefront Shaping Control For Sensing Applications, Pablo Jara Apr 2026

Harnessing Wavefront Shaping Control For Sensing Applications, Pablo Jara

Miners Solving for Tomorrow Research Conference

Diffuse optical tomography (DOT) and functional near-infrared spectroscopy (fNIRS) enable deep, non-invasive sensing in biological tissue but are fundamentally limited by the photon budget - most injected light is lost to scattering before reaching the detector. Wavefront shaping (WFS) can enhance signal strength inside scattering media via interference, but the conventional diffusion-based sensitivity model breaks down under coherent illumination. We develop a microscopic theory of optical sensitivity that captures interference effects neglected by diffusion theory. We prove analytically that the microscopic and diffusive descriptions coincide under random illumination and identify WFS strategies that enhance sensitivity beyond this limit. The maximum …


Optimization Of Niobium Film For Particle Accelerators And Quantum Applications, Bektur Abdisatarov Apr 2026

Optimization Of Niobium Film For Particle Accelerators And Quantum Applications, Bektur Abdisatarov

Electrical & Computer Engineering Theses & Dissertations

Niobium (Nb) films play a central role in superconducting technologies used in particle accelerators and superconducting quantum circuits. Optimizing the physical properties of Nb films is therefore critical for improving both radiofrequency (RF) performance in superconducting radiofrequency (SRF) cavities and coherence in superconducting qubits. This thesis investigates the relationship between Nb film microstructure, impurity content, and electromagnetic response across these two application domains.

For particle accelerator applications, we studied Nb films deposited using high-power impulse magnetron sputtering (HiPIMS) with DC bias onto a 1.3 GHz elliptical SRF cavity. Nb film cavities exhibit a pronounced medium-field Q-slope, limiting their achievable accelerating …


Fabrication And Analysis Of Bi₂O₃/Si Heterojunction For Solar Cell Applications, Maher Khaleel Ibrahim, Assel Mustafa Abdul Majeed, Randa Kamel Husain, Jamal M. Rzaij Mar 2026

Fabrication And Analysis Of Bi₂O₃/Si Heterojunction For Solar Cell Applications, Maher Khaleel Ibrahim, Assel Mustafa Abdul Majeed, Randa Kamel Husain, Jamal M. Rzaij

Al-Bahir

Bismuth oxide (Bi₂O₃) nanoparticles were synthesized via a green route and integrated into Bi₂O₃/Si heterojunction solar cells. Structural analysis confirmed the monoclinic α-Bi₂O₃ phase with a nanoscale crystallite size, while SEM revealed a uniform morphology. Optical studies showed a direct band gap suitable for absorbing visible light. Photoluminescence spectra exhibited dual emissions at 498 nm and 250 nm, attributed to defect states and quantum confinement, highlighting the dual role of Bi₂O₃ as both absorber and transparent window layer. Electrical characterization under dark conditions demonstrated rectifying diode behavior, confirming the formation of a junction. Capacitance–voltage analysis yielded a built-in potential of …


Extension Of The Local Vibrational Mode Theory To Periodic Systems, Filippo Bodo Mar 2026

Extension Of The Local Vibrational Mode Theory To Periodic Systems, Filippo Bodo

Chemistry Theses and Dissertations

Over the years, vibrational spectroscopy was used to gain a deeper understanding of the electronic structure and the chemical bond in both molecular and periodic systems. In this framework, the Local Vibrational Mode Theory (LVMT), as first introduced by Konkoli and Cremer in 1998, provides a unique tool to quantify the strength of a chemical bond, and better interpret the molecular vibrational spectra, thanks to the adiabatic force constants ($k^a$) and the composition of normal modes (CNM). While LVMT was originally developed for molecular systems, its application to periodic solids has remained limited. This thesis presents a complete and systematic …


Characterization Of Physical And Structural Properties In A Quaternary Li2o-B2o3-Bi2o3-V2o5 Glass System, Alan Ikram Ahmed, Mowfaq Jalil Ahmed Mar 2026

Characterization Of Physical And Structural Properties In A Quaternary Li2o-B2o3-Bi2o3-V2o5 Glass System, Alan Ikram Ahmed, Mowfaq Jalil Ahmed

Polytechnic Journal

Borate-based glasses modified with alkali oxides are of considerable interest due to their tunable structural and optical properties, which are important for optical and energy storage applications. In this work, glasses with a novel nominal composition of xLi2O-(75-x) B2O3—20Bi2O3—5V2O5, in which (x ¼ 5, 10, 15, 20, 25 mol %) were produced using the traditional melt-quenching technique to investigate the effect of substituting the glass former B2O3 with the modifier Li2O. The structural and optical properties were examined by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and UV—visible spectroscopy. The XRD analysis confirms the amorphous nature of the samples produced. …


Electronic Transport In Twisted Bilayer Tungsten Diselenides, Walid Zaher Jan 2026

Electronic Transport In Twisted Bilayer Tungsten Diselenides, Walid Zaher

Theses and Dissertations

This thesis investigates density waves (DWs) in twisted bilayer tungsten diselenide (tWSe₂) using a mean field approximation, with a focus on electron-electron interactions, and the system’s free energy at zero temperature. For the mean field approximation, the study initially employed same-spin nesting vectors, which were found insufficient to induce DWs formation. In contrast, when opposite-spin nesting vectors were used, DWs emerged, indicating that these vectors can support DWs formation. The plots were produced under perfect nesting conditions, where van Hove singularities (VHS) occur. At zero temperature, perfect nesting provides a complete picture of the upper limit of DWs formation, as …


Ultrafast Terahertz Spectroscopy And The Suppression Of Superconductivity In Strained Iron Selenide Below 1 Kelvin, Tracy Glen Hastings Jan 2026

Ultrafast Terahertz Spectroscopy And The Suppression Of Superconductivity In Strained Iron Selenide Below 1 Kelvin, Tracy Glen Hastings

ETDs from 2020-2029

We report on terahertz time-domain spectroscopy measurements of iron selenide thin films of various thicknesses grown on a magnesium oxide substrate, focusing on the frequency-dependent complex conductivity in the range of 0.25 - 7 THz. By an- alyzing films with and without an approximately 100 nm thick Se capping layer, we examined the role of oxidation in the suppression of superconductivity. X-ray photo- electron spectroscopy data confirmed that oxidation was effectively mitigated, yet the films exhibited insulating behavior down to 200 mK, a temperature range that has not been extensively studied in this system. Our results indicate that the suppression …


Enhanced Superconductivity And Vortex Dynamics In Quasi-1d Tas2 Nanowires, Mathew Pollard, Visakha Ho, Clarissa Wisner, Eric W. Bohannan, Yew San Hor Jan 2026

Enhanced Superconductivity And Vortex Dynamics In Quasi-1d Tas2 Nanowires, Mathew Pollard, Visakha Ho, Clarissa Wisner, Eric W. Bohannan, Yew San Hor

Chemistry Faculty Research & Creative Works

We report the synthesis of high-quality 2H-TaS2 nanowires via a controlled two-step conversion process from TaS3 precursors, achieving robust superconductivity with a transition temperature T c ≈ 3.6K, which is significantly higher than bulk 2H-TaS2 (T c ≈ 0.8K). Structural and compositional analyses confirm phase purity and preserved one-dimensional morphology, while magneto transport measurements reveal an enhanced upper critical field μ 0 H c2 (2K)≈5 T, far exceeding the bulk value (μ0Hc2 (0)≈1.17T), attributed to dimensional confinement and suppression of charge-density wave order. Magnetic characterization demonstrates complex vortex dynamics, including flux jumps and a …


Magnetic Anisotropy Engineering In Rare-Earth-Free Iron-Based Magnetic Materials, Pramanand Joshi Jan 2026

Magnetic Anisotropy Engineering In Rare-Earth-Free Iron-Based Magnetic Materials, Pramanand Joshi

Physics Dissertations - Archive

The development of high-performance, rare-earth-free hard magnetic materials is critical for next-generation energy, information, and spin-based technologies. This dissertation investigates structure-property relationships in iron-based magnetic systems, including iron carbides, Fe-Co-B boride alloys, hexaferrites, and FeCo nanostructures, synthesized via chemical and metallurgical routes. Through controlled synthesis and comprehensive structural and magnetic characterization, this work demonstrates that magnetic anisotropy, coercivity, and thermal stability can be systematically controlled through morphology design, compositional tuning, microstructural refinement, and interparticle interaction modulation.

Morphology-driven enhancement of magnetic properties, particularly coercivity and blocking temperature, is established in phase-pure Fe5C2 nanostructures. By precisely controlling particle geometry, …


Applications Of Doppler Broadening Spectroscopy For The Characterization Of The Surface And Near Surface Of Two-Dimensional Heterostructures, Hany M. Mahdy Jan 2026

Applications Of Doppler Broadening Spectroscopy For The Characterization Of The Surface And Near Surface Of Two-Dimensional Heterostructures, Hany M. Mahdy

Physics Dissertations

This dissertation describes experiments and the analysis of Doppler broadening spectroscopy applied to metal surfaces (Cu, Ag, Au), graphene/Cu heterostructures, and SiGe heterostructures, with particular emphasis on the development of new approaches for extracting quantitative information from annihilation spectra.

The first part establishes the capability of Doppler broadening spectroscopy, particularly coincidence Doppler broadening (CDB), as a surface-sensitive technique. Measurements on clean and adsorbate-covered Cu, Ag, and Au surfaces demonstrate that Doppler-broadened annihilation spectra retain element-specific signatures from the topmost atomic layer. New analysis methods based on ratio-curve modeling enable identification and quantification of sub-monolayer adsorbates, including sulfur, oxygen, selenium, and …