Condensed Matter Physics Commons^™

Functionalized Go Nanoplatelets With Folic Acid As A Novel Material For Boosting Humidity Sensing Of Chitosan/Pva Nanocomposites For Active Food Packaging, Mohamed Morsy

Nanotechnology Research Centre

No abstract provided.

Enhanced Acousto-Optic Properties Of Silicon Carbide Based Layered Structure, Namrata Dewan Soni

Al-Bahir

This study investigates the feasibility of using silicon carbide-based layered surface acoustic wave (SAW) devices in acousto-optic applications. The acousto-optic properties of the temperature-stable layered structure TeO3/SiC/128oY-X LiNbO3 are investigated through theoretical analysis. This analysis includes the evaluation of key parameters such as the overlap integral, figure of merit, and diffraction efficiency. The SAW propagation characteristics and field profiles required for these calculations are obtained using SAW software. Results show that the layered structure has high diffraction efficiency of nearly 96% and a promising value for the acousto-optic figure of merit, indicating potential use in low driving power acousto-optic devices. …

Phase Transitions And Magnetocaloric Effects In Metastable Phases Of Intermetallic Compounds, Tej Bahadur Poudel Chhetri

LSU Doctoral Dissertations

The interplay between spin and lattice degrees of freedom in magnetic materials often results in interesting magnetoresponsive effects. The magnetocaloric effect is one such magnetothermal phenomenon that may be utilized in energy-efficient magnetic cooling systems. This effect becomes more prominent near a coupling of magnetic and structural transitions, i.e., magnetostructural transitions (MSTs). This dissertation investigates phase transitions (magnetic and structural) in metastable phases of MnNiGe- and MnCoGe-based compounds generated through high-pressure synthesis/annealing and thermal quenching techniques and assesses their magnetocaloric effects.

First, the effects of doping, hydrostatic pressure, and thermal quenching on phase transitions and related magnetocaloric effects in Mn …

Dynamical Polymer Chain Heterogeneities And Their Impacts On The Glass Transition, William Forrest Drayer

USF Tampa Graduate Theses and Dissertations

The utilization of polymeric materials has endured since prehistory, at first unknowinglyin the form of natural biopolymers such as wood and leather, culminating and continuing through the development of the plastics industry in the early twentieth century. Polymers, along with other materials including silicate glasses, readily exhibit the glass transition upon quenching: a continuous but rapid change from viscous (liquid) to elastic (solid) behavior. The physics surrounding the glass transition have been studied for over a century; while considerable progress has been made, there remains no universally accepted predictive theory of the glass transition. Modern development of glassy materials consists …

Thermal, Magnetic, And Electrical Properties Of Thin Films And Nanostructures: From Magnetic Insulators To Organic Thermoelectrics, Michael J. M. Roos

Electronic Theses and Dissertations

Modern fabrication and growth techniques allow for the development of increasingly smaller and more complex solid state structures, the characterization of which require highly specialized measurement platforms. In this dissertation I present the development of techniques and instrumentation used in magnetic, thermal, and electrical property measurements of thin films and nanostructures. The understanding of trapped-flux induced artifacts in SQUID magnetometry of large paramagnetic substrates allows for the resolution of increasingly small moments. Using these methods, the antiferromagnetic coupling of the interface between a Y₃Fe₅O₁₂ film and Gd₃Ga₅O₁₂substrate is quantitatively …

The Study Of Excitons In 2d Novel Materials And Their Van Der Waals Heterostructures In The Magnetic Field, Anastasia Spiridonova

Dissertations, Theses, and Capstone Projects

This research focuses on the direct and indirect excitons in Rydberg states in monolayers, bilayers, and van der Waals heterostructures composed of 2D semiconductors in the presence of the external magnetic field. In our work, we report binding energies of direct and indirect excitons in Rydberg states, the energy contribution from the magnetic field to the binding energies of magnetoexcitons, and diamagnetic coefficients (DMCs) of magnetoexcitons.

We study isotropic materials: transition metal dichalcogenides, TMDCs (WSe₂, WS₂, MoSe₂, MoS₂), and Xenes (silicene, germanene, stanene), and anisotropic materials: phosphorene and transition metal trichalcogenides, TMTCs …

Design And Implementation Of Montmorillonite Clay-Based Catalyst For Carbon Nanotube Synthesizing, Mohamed Morsy

Nanotechnology Research Centre

No abstract provided.

Synthesis And Functional Properties Of La2fecro6 Based Nanostructures, Mohamed Morsy

Nanotechnology Research Centre

No abstract provided.

Effective Nanomembranes From Chitosan/Pva Blend Decorated Graphene Oxide With Gum Rosin And Silver Nanoparticles For Removal Of Heavy Metals And Microbes From Water Resources, Mohamed Morsy

Nanotechnology Research Centre

No abstract provided.

Effective Non-Hermiticity And Topology In Markovian Quadratic Bosonic Dynamics, Vincent Paul Flynn

Dartmouth College Ph.D Dissertations

Recently, there has been an explosion of interest in re-imagining many-body quantum phenomena beyond equilibrium. One such effort has extended the symmetry-protected topological (SPT) phase classification of non-interacting fermions to driven and dissipative settings, uncovering novel topological phenomena that are not known to exist in equilibrium which may have wide-ranging applications in quantum science. Similar physics in non-interacting bosonic systems has remained elusive. Even at equilibrium, an "effective non-Hermiticity" intrinsic to bosonic Hamiltonians poses theoretical challenges. While this non-Hermiticity has been acknowledged, its implications have not been explored in-depth. Beyond this dynamical peculiarity, major roadblocks have arisen in the search …

Oxidation Resistance Of An Atomically Flat Cu(111) Surface: A First-Principles Study, Bipin Lamichhane

Theses and Dissertations

The first-principles calculation based on density functional theory (DFT) was used to study the oxidation resistance of atomically flat and atomic-step edges of Cu(111), diffusion of Cu atoms in different surfaces of alumina and interface properties of alumina and Cu(111), and magnetic properties of Mn-substituted strontium hexaferrite. The dissociation of oxygen molecules is the primary reason for the corrosion of metals, which deteriorates their application. Cu(111) flat surface, mono-atomic, and multi-atomic step edges were used to study oxygen diffusion. Penetration of oxygen on a Cu(111) flat surface requires high energy, indicating oxidation resistance. Our DFT result of oxygen diffusion into …

Origin And Structure Of The First Sharp Diffraction Peak Of Amorphous Solids, Devilal Dahal

Dissertations

Several explanations have been reported in the literature about the origin of extended-range oscillations (EROs) in the atomic pair-correlation function of amorphous materials. Although the radial ordering beyond the short-range order of about 5 Å has been extensively studied in amorphous materials, the exact nature of the radial ordering beyond a nanometer is still not resolved. This dissertation address this problem and explains the nature of the EROs by using high-quality models of amorphous silicon (a-Si) obtained from Monte Carlo and Molecular Dynamics simulations. The extended-range ordering in a-Si is examined through radial oscillations on the length …

Domain Wall Saddle Point Morphology In Ferroelectric Triglycine Sulfate, C. J. Mccluskey, A. Kumar, Alexei Gruverman, I. Luk’Yanchuk, J. M. Gregg

Alexei Gruverman Publications

Ferroelectric domain walls, across which there is a divergence in polarization, usually have enhanced electrical conductivity relative to bulk. However, in lead germanate, head-to-head and tail-to-tail walls are electrically insulating. Recent studies have shown that this is because, when oppositely oriented domains meet, polar divergence is obviated by a combination of domain bifurcation and suspected local dipolar rotation. To explore the uniqueness, or otherwise, of this microstructure, we have used tomographic piezoresponse force microscopy to map three-dimensional domain morphologies in another uniaxial ferroelectric system: triglycine sulfate. This mapping reveals an abundance of domain wall saddle points, which are characteristic of …

Fabrication Of Black Phosphorus Terahertz Photoconductive Antennas, Nathan Tanner Sawyers

Physics Undergraduate Honors Theses

Terahertz (THz) photoconductive antennas (PCAs) using 40nm thin-film flakes of black phosphorus (BP) and hexagonal boron nitride (hBN) have been shown computationally to be capable of THz emission comparable to those based on GaAs [2]. In this paper, I briefly describe the scientific and practical interest in THz emissions and explain what warrants research into black phosphorus as a photoconductive semiconductor in THz devices. Furthermore, I outline the basic principle of how these antennas work and mention alternative designs produced by other researchers in the past. Finally, I summarize the fabrication process of these antennas, as well as the measurements …

Methods For Preparing And Characterizing Granular Materials For Electron Yield Measurements, Tom Keaton

All Graduate Plan B and other Reports, Spring 1920 to Spring 2023

This work presents a systematic study on sample preparation methods and accuracy of electron yield (EY) measurements of highly insulating, granular materials. EY measurements of highly insulating materials, especially those with high EY, are challenging due to the effects of sample charging even for very low fluence electron probe beams. EY measurements of particulates are complicated by: (i) roughness effects from particulate size, shape, coverage, and compactness; (ii) particle adhesion; (iii) substrate contributions; and (iv) electrostatic repulsion and potential barriers from charged particles and substrates. Numerous methods were explored to rigidly affix particles on conducting substrates at varying coverages for …

Automating The Determination Of Tight-Binding Representations For Two-Dimensional Ferroelectrics, Joseph Roll

Physics Undergraduate Honors Theses

Two-dimensional (atomically thin) materials have been greatly explored in the last two decades since the exfoliation of graphene in 2004. Since then, many exotic material properties have been shown for these systems; these new properties often arise from certain crystal symmetries or lack thereof. One of interest is ferroelectricity in which a noncentrosymmetric crystal structure can lead to a switchable intrinsic electric dipole in our material. This can then lead to second-harmonic generation in which two photons enter a material at a given frequency and one photon exits the material at double the original frequency. The study presented here makes …

Computational Modeling Of Superconductivity From The Set Of Time-Dependent Ginzburg-Landau Equations For Advancements In Theory And Applications, Iris Mowgood

Computational and Data Sciences (PhD) Dissertations

A full review of the research conducted and published during my PhD studies in Computational and Data Sciences at Chapman University, under the advisement of Dr. Armen Gulian, are presented. Using the set of time-dependent Ginzburg-Landau (TDGL) equations with inclusion of the interference current and the non-equilibrium phonon term, we modeled the dynamics of superconductors in various theory revealing states and practical purposes. A review of the history and phenomenon of superconductivity, including modern applications, is introduced. The Josephson effect and associated Josephson junction are discussed for comparison to our analogous results with the 1-D superconducting wire. The mathematics of …

Designing Noncentrosymmetric Multifunctional Materials, Ebube Oyeka

All Dissertations

Noncentrosymmetric (NCS) materials with crystal lattices lacking spatial inversion symmetry display a wide range of exciting functionalities. This dissertation covers two classes of functional NCS materials: magnetic skyrmion-host compounds and multifunctional materials. Magnetic skyrmion and multifunctional materials combining optical and magnetic responses are providing avenues for developing and optimizing the performance of electronic devices that can have uses in memory storage, laser technology, medicine, sensors, etc. The formation of skyrmions is driven by asymmetric Dzyaloshinskii–Moriya (DM) interaction facilitated by broken spatial inversion symmetry and large spin-orbit coupling (SOC), while multiple functionalities arise when spin carriers and optical chromophores are optimally …

Exploring Ferroelectric Phenomena In Batio3, Linbo3, And Liznsb: From Extended Oxygen Vacancies To Tri-Stable Polarization And Giant Hyperferroelectricity, Shaohui Qiu

Graduate Theses and Dissertations

This dissertation presents three projects that investigate the complex phenomena of ferroelectricity under different conditions in BaTiO3, LiNbO3, and LiZnSb using first-principles density functional calculations. Extended defects in ferroelectric solids play a crucial role in reducing the lifetime and performance of ferroelectric devices by causing fatigue, domain pinning, and aging. Thus, understanding their impact is of critical importance for the development of reliable and high-performance ferroelectric devices. In addition, hyperferroelectricity is an intriguing phenomenon that has attracted much attention in recent years. Despite the existence of depolarization field, spontaneous polarization persists under an open-circuit boundary condition (OCBC), making hyperferroelectric materials …

Magnetic Properties Of Polycrystalline Spinel Oxides From Solid State Reaction, Camden Olds

Honors Program: Senior Projects (Public)

Spinel crystal materials of nickel, cobalt, and iron oxides have seen abundant research for their strong conductivity, ferromagnetic and ferroelectric properties, and their catalytic uses. These can be synthesized by a number of means. This project explores the use of the solid state synthesis method, which benefits from simplicity, of this family of materials, looking for interesting phase shift lines in the triangle between of varying compositions of these three metals.

Nickel cobaltite and other related spinels were synthesized from two different solid state approaches and characterized using XRD and SQUID magnetometry. The range 0.5-0.6 of molar ratios of nickel …