Physical Sciences and Mathematics Commons^™

Electronic And Magnetic Order As A Function Of Doping In Mixed-Valent La1-Xsrxmn03 Thin Films, James Payne, Dakota Brown, Calleigh Brannan, Tom Pekarek, Maitri Warusawithana

Showcase of Osprey Advancements in Research and Scholarship (SOARS)

The rich phase diagram in mixed-valent manganites has been intensely studied in bulk crystals as a function of chemical doping. Here we study the effect of doping in La1-xSrxMnO3 thin films by varying the Sr/La ratio between samples. These thin films are grown using ozone assisted molecular beam epitaxy with carefully controlled stoichiometry for a range of doping from x = 0.0 to x = 0.5. Our electronic measurements reveal a crossover from a Mott insulator to a metallic ground state as x is increased. In the metallic ground state we observe a metal-to-insulator transition coincident with a ferromagnetic-to-paramagnetic ordering …

Reduced Dimensionality Effects In Ferromagnetic Behavior In La1-Xsrxmno3, C. A. Brennan, M. P. Warusawithana, J. Payne, D. Brown, T. M. Pekarek

Showcase of Osprey Advancements in Research and Scholarship (SOARS)

We study the magnetic properties of La1-xSrxMnO3 samples for concentrations x, 0 ≤ x ≤ 0.5. An analysis is done to accurately determine the transition temperature or critical temperature. Magnetic phase diagrams showing the various concentrations at different temperatures will be determined for our thin films. Using the phase diagrams for both bulk and thin film materials can show how reducing the dimensionality from the third dimension to approaching the second-dimension affects the phase diagram.

Improving Photon Number Resolution In Superconducting Nanowire Single-Photon Detectors With Integrated Impedance Tapers, Bladimiro E. Valbuena, Daniel F. Santavicca

Showcase of Osprey Advancements in Research and Scholarship (SOARS)

Simulations are run to optimize the ability to resolve the number of photons detected from the pulse height by a Superconducting Nanowire Single-Photon Detector (SNSPD). This is set up in a manner that features an impedance-matching transmission line taper that provides a characteristic impedance which transitions from kΩ to 50 Ω, with the taper providing an effective load impedance that outputs pulses with not only larger amplitudes but also showed a distinct separation for multi-photon events. The first part of this project tries to computationally match the experimental results obtained by our collaborators at MIT. Once these results are achieved, …

Characterization Of Magma Storage And Dynamics At Akutan, Semisopochnoi, And Okmok Volcanoes From Analytical And Numerical Models Of Geodetic, Seismic, And Petrologic Data, Kimberly Degrandpre

Earth Sciences Theses and Dissertations

Volcanic eruptions can cause significant socioeconomic loss, but a better understanding of the processes and dynamics influencing the evolution of volcanic plumbing systems will advance the development of eruption forecasting models that will ultimately mitigate hazards and risks associated with eruptive events. Geologic and geophysical data must be integrated in 3D, finite- element, multiphysical, numerical models to define the coupled evolution of magmatic and crustal stress regimes in volcanic environments, but in data limited regions this is not always an option. The remote nature of the Aleutian Island Arc restricts ground-based monitoring and sampling efforts, and due to sparse temporal …

Size-Controlled Synthesis Of Nickel Nanoparticles Enclosed In Carbon Nanocages, Felicity Peebles, Grigorii Rudakov, Gamini U. Sumanasekera

Undergraduate Arts and Research Showcase

We have demonstrated a simple, scalable, and tunable method of obtaining densely packed Ni Nanoparticles encapsulated in Carbon Nanocages (Ni@CNCs). Using a facile method, it was shown that via a simple annealing process of precursor based on nickel acetate and citric acid, Ni@CNCs with sizes varying from 5 to 20 nm can be synthesized by changing the heating ramp rate during the synthesis from 25 to 53 °C/min. The final temperature of 600 °C was held for 10 min, and was the same for all the samples. X-Ray Diffraction (XRD) multiple peaks analysis was performed to show large Ni nanoparticles …

Characterization Of A Trochoidal Electron Monochromator, Jesse Kruse

Honors Theses

This thesis presents a quantitative study of a trochoidal electron monochromator and attempts to observe the 2p^53p^2 resonance in neon. A detailed description of the experimental apparatus, including the electron beam system, the vacuum system, and the light analysis system, is presented first. Then, we discuss the theory of how the electron beam is monochromatized, how we measured monochomatization, and how we analyze the light being emitted from the collision cell. The light analysis system is capable of accurately measuring the relative Stokes parameters for any polarization of light, and the electron beam system is capable of producing electron beams …

Host-Galaxy Morphology Of 14 Local Active Galaxies As Imaged By The Hubble Space Telescope, Tomas Henry Snyder

Physics

Active galactic nuclei (AGNs) are galaxies with super-massive black holes, that are undergoing accretion, at their centers. The study of these objects provides us with a deeper understanding of how the black holes evolved along with their host galaxies since black hole mass is highly correlated with bulge mass. A sample of 66 AGNs were imaged using the Hubble Space Telescope (HST) and 14 of those are analyzed in this paper to determine their structure, bulge luminosity, and bulge type. The program GALFIT is implemented to determine these parameters, that will be used in further research in the future. These …

Designing Writing Intensive Upper Division Laboratories In Physics, Sara Callori

Q2S Enhancing Pedagogy

California State University San Bernardino is currently transitioning from quarters to semesters, starting in Fall 2020. As part of this transition, the Department of Physics has transformed its curriculum to better suit the needs of its students. One major facet of this redesign has been the creation of two writing intensive, upper division laboratory courses. From a practical standpoint, under the revamped general education program, we are able to incorporate upper division writing into the major. More importantly, there are many benefits where having a writing-intensive major course aligns with program goals and professional organization recommendations. This includes designing activities …

A Writing Intensive Upper Division Astrophysics/Planetary Science Course, Laura M. Woodney

Q2S Enhancing Pedagogy

This poster describes the major writing components of an upper division Astronomy or Planetary Science course. These components are intended to be integrated throughout the semester along with the content of the course. The papers the instructor chooses for the scaffolded assignments should compliment/enhance the content the students are learning in the course. This project used the "Backwards Design" method from Bean (2011, citation in poster): where the instructor first identifies the final project, determines what challenges the students will encounter attempting to do that project, and then builds scaffolded assignments intended to address each of these challenges. This presentation …

Edge-Coupling Of O-Band Inp Etched-Facet Lasers To Polymer Waveguides On Soi By Micro-Transfer-Printing, Ruggero Loi, Steven Kelleher, Raja Fazan Gul, Antonio Jose Trindade, David Gomez, Liam O'Faolain, Brian Corbett, Simone Iadanza, Brendan Roycroft, James O'Callaghan, Lei Liu, Kevin Thomas, Agnieszka Gocalinska, Emanuele Pelucchi, Alexander Farrell

Cappa Publications

O-band InP etched facets lasers were heterogeneously integrated by micro-transfer-printing into a 1.54~\mu \text{m} deep recess created in the 3~\mu \text{m} thick oxide layer of a 220 nm SOI wafer. A 7\times 1.5\,\,\mu \text{m}^{2} cross-section, 2 mm long multimode polymer waveguide was aligned to the ridge post-integration by e-beam lithography with < 0.7~\mu \text{m} lateral misalignment and incorporated a tapered silicon waveguide. A 170 nm thick metal layer positioned at the bottom of the recess adjusts the vertical alignment of the laser and serves as a thermal via to sink the heat to the Si substrate. This strategy shows a roadmap for active polymer waveguide-based photonic integrated circuits.

Structuring Light For Investigating Optical Vortices, Andrew Voitiv, Mark Siemens

DU Undergraduate Research Journal Archive

Vortices are well known in our world: tornadoes, hurricanes, and quickly stirred iced tea all demonstrate the vortex phenomenon. In addition to these classical fluids, vortices exist in laser light. While classical fluid vortex dynamics is one of the oldest studied physics problems, the study of optical vortices is only a few decades old. Paralleling the community’s curiosity of quantized vortices in quantum fluids, such as super fluid helium and Bose-Einstein condensate, there is immense interest in the study of optical vortices. In this article, we cover the basic theory of structuring light to generate optical vortices and then discuss …

Tools For Physicistsl Creating A Major-Based Foundational Course, Carol Hood

Q2S Enhancing Pedagogy

Pulling extensively from the recommendations from Phys21: Preparing Physics Students for 21st Century Careers¹, a joint AAPT-APS committee report, we created a new semester course for all incoming physics majors, regardless of their math preparation. The Tools for Physicists course will attempt to set a foundation for what physicists do, why you would want to be one, and what you need to be successful.

Improved Contacts And Device Performance In Mos2 Transistors Using 2d Semiconductor Interlayers, Kraig Andrews

Wayne State University Dissertations

The rapid growth of modern electronics industry over the past half-century has been sustained by the continued miniaturization of silicon-based electronics. However, as fundamental limits approach, there is a need to search for viable alternative materials for next-generation electronics in the post-silicon era. Two-dimensional (2D) semiconductors such as transition metal dichalcogenides (TMDs) have attracted much attention due to their atomic thickness, absence of dangling bonds and moderately high carrier mobility. However, achieving low-resistance contacts has been major impediment in developing high-performance field-effect transistors (FETs) based on 2D semiconductors. A substantial Schottky barrier (SB) is often present at the metal/2D-semicondcutor interface, …

Development Of Embedded Atom Method Interatomic Potentials For Ge-Sn-Si Ternary And Constituent Binary Alloys For Modeling Material Crystallization, Sudip Acharya

Browse all Theses and Dissertations

Group IV elements based nanoelectronics devices (mainly Si and Ge based devices) have been developed and improved over a long period of time and are the most influencing materials of semiconductor electronics, but due to their indirect bandgap their use in optoelectronics is limited. Alternatively, new Group IV alloys comprised of Ge, Si, and Sn semiconductor materials have emerged as attractive options for various electronic and optoelectronic applications. The binary and ternary alloys provide strain and energy bandgap engineering by controlling element content, a route for realizing direct-transition semiconductors, improvement in interface and defect properties, and a reduction of the …

Visual Storytelling Of Scientific Data: Collaborations Between Physics And Graphic Design In The College Classroom, Eric M. Edlund, Szilvia Kadas

The SUNY Journal of the Scholarship of Engagement: JoSE

The Common Problem Pedagogy (CPP) project, a learning initiative implemented in four SUNY schools, aims to provide students with multidisciplinary, project-based experiences, and to foster a culture of such pedagogy among faculty. This work describes one CPP project that was conducted at SUNY Cortland during the Spring 2019 semester that brought together students from physics and graphic design disciplines. The goal of this project was to identify issues of environmental and social concern, develop numerical models to represent the effects of possible policy actions, and to communicate the meaning of this work as infographics suitable for a non-expert, public audience. …

Quantifying Electron Precipitation In The Van Allen Radiation Belts, Timothy Raeder

Honors Theses and Capstones

The spatial and temporal distribution of high energy electron precipitation from the Van Allen radiation belts is not currently well-understood. The FIREBIRD-II mission (2015-present) and the Van Allen Probes (2012-2019) provide a unique opportunity to examine the behaviors and drivers of high energy electron precipitation. This study quantifies electron precipitation observed by FIREBIRD-II as a function of radial distance (L-shell), magnetic local time (MLT), hemisphere, and geomagnetic indices (Kp). Electron precipitation was observed to peak at L-shell 4.5-5. Regions of elevated electron precipitation were identified at L-shell 4-6 at dawn (MLT 6-9) and dusk (MLT 15-21). Hemisphere filtering indicated very …

The Hydrostatics And Hydrodynamics Of Prominent Heteromorph Ammonoid Morphotypes And The Functional Morphology Of Ammonitic Septa, David Joseph Peterman

Browse all Theses and Dissertations

Ammonoid cephalopods have chambered shells that regulated buoyancy. The morphology of their shells strongly influenced the physical properties acting on these animals during life. Heteromorph ammonoids, which undergo changes in coiling throughout ontogeny, are the focus of this dissertation. The biomechanics of these cephalopods are investigated in a framework involving functional morphology, paleoecology, and possible modes of life. Constructional constraints were investigated for the marginally-corrugated septal walls within the chambered ammonoid shell. These constraints governed the positive relationship between septal complexity and terminal size. Furthermore, increased septal complexity facilitated liquid retention via surface tension. More complex septa would have increased …

A Case Studies Approach To Teaching Introductory Physics, Gregory A. Dilisi, Alison Chaney*, Stella Mclean*, Richard Rarick

2020 Faculty Bibliography

No abstract provided.

The Influence Network In 1+1 Dimensions, James Lyons Walsh

Legacy Theses & Dissertations (2009 - 2024)

The Influence Network research program [1] [2] [3] [4] starts with a very simple model

Numerical Study Of Klebanov-Tarnopolsky Models, Nathaniel Avish

Legacy Theses & Dissertations (2009 - 2024)

In this thesis we perform a numerical study of the $O(N_1)\times O(N_2)\times O(N_3)$ Klebanov-Tarnopolsky (KT) model, whose large-$N$ limit is expected to admit a simple gravitational dual under the AdS/CFT correspondence. We study the $25$ special cases of the KT model which have fewer than $2^{13}$ states. For all such systems we diagonalize the Hamiltonian matrices, identify sectors which have specific charges, and compute the number of singlet states. Our findings support prior evidence that the KT model can be exactly diagonalized and therefore may have an exact analytic solution, which would be helpful in learning more about the AdS/CFT …

Evolution Of Electron Properties After Nanosecond Repetitively Pulsed Discharges In Air Measured By Thomson Scattering, Chase S. Murray

Browse all Theses and Dissertations

This work was an investigation of nanosecond repetitively pulsed discharges in air by measuring the evolution of electron density and electron temperature between pulses using Thomson scattering of laser light. Bursts of repetitive pulses within several microseconds after the initial pulse were found to exhibit a coupling effect and create an even higher electron density than the initial pulse. The wide range of temperatures and densities of the electrons existing between pulses allow an opportunity to explore both the collective and non-collective regimes of Thomson scattering. By measuring electron density and temperature at a variety of times, an accurate description …

Comparative Experimental And Theoretical Study Of Dopamine And Serotonin Interaction, Jose A. Guerrero

Open Access Theses & Dissertations

To accurately identify and measure the concentrations of dopamine (DA) and serotonin (5-HT) in mixtures of these neurotransmitters without labeling, a comprehensive, comparative computational and Raman experimental analysis is provided. While the distinction between these two analytes may be accomplished for concentrations in the millimolar range of these mixtures, their accurate quantification remains unattainable. As shown for the first time in this study, potential creation of a new composite resulting from their interactions with each other could be a reason for this lack of quantification.

Although this new hydrogen-bonded complex greatly complicates future analyte differentiation and quantification at concentrations typical …

Tell All The Truth But Tell It Slant: The Essential Role Of Metaphor In Constructing Physics, Theodora E. Zastrocky

Regis University Student Publications (comprehensive collection)

The common understanding of interdisciplinary work is that it is a partial merger of two related disciplines, such as history and philosophy or chemistry and biology. This understanding does not account for the interdisciplinary work possible between seemingly disparate disciplines, such as physics and poetry, and as a result this ignores the immense potential of true interdisciplinary study. Interdisciplinary work has the power to further research, better educate students, and redefine the script that dictates which people are allowed within certain disciplines, allowing for more diverse and inclusive fields of study. Zastrocky looks at metaphor in physics as a way …

One-Dimensional Kinetic Particle-In-Cell Simulations Of Various Plasma Distributions, Richard N. Vanderburgh

Browse all Theses and Dissertations

A one-dimensional kinetic particle-in-cell (PIC) MATLAB simulation was created to demonstrate the time-evolution of various plasma distributions. Building on previous plasma PIC programs written in FORTRAN and Python, this work recreates the computational and diagnostic tools of these packages in a more user- and educational-friendly development environment. Plasma quantities such as plasma frequency and species charge-mass ratios are arbitrarily defined. A one-dimensional spatial environment is defined by total length and number and size of spatial grid points. In the first time-step, charged particles are given initial positions and velocities on a spatial grid. After initialization, the program solves for the …

Characterization Of A Novel Terahertz Chemical Sensor, Daniel J. Tyree

Browse all Theses and Dissertations

A recently constructed novel analytical tabletop terahertz (THz) chemical sensor capable of detecting a wide range of gases with high sensitivity and specificity was characterized to assess its performance over a range of operational parameters. The sensor was designed with an objective of quantifying composition of exhaled human breath, where target concentrations span part per trillion (ppt) to part per billion (ppb) level of dilutions. The sensor utilizes terahertz rotational spectroscopy of sampled gases for quantification of dilutions. The sensor occupies a volume of ~ 2 ft3 and incorporates a coiled absorption cell, thermal desorption tubes, and all necessary electronic …

Electron Tunneling And X-Ray Photoelectron Spectoscopy Studies Of The Superconductiong Properties Of Nitrogen-Doped Niobium Resonator Cavities, Eric M. Lechner, Basu Dev Oli, Junki Makita, Gianluigi Ciovati, Alex Gurevich, Maria Iavarone

Physics Faculty Publications

We use scanning tunneling microscopy (STM) and spectroscopy (STS), and x-ray photoelectron spectroscopy (XPS) to investigate the effect of nitrogen doping on the surface electronic and chemical structures of cutouts from superconducting Nb radio-frequency cavities. The goal of this work is to get insights into the fundamental physics and materials mechanisms behind the striking decrease of the surface resistance with the radio-frequency magnetic field, which has been observed on N-doped Nb cavities. Our XPS measurements reveal significantly more oxidized Nb 3d states and a thinner metallic suboxide layer on the N-doped Nb surfaces, which is also confirmed by tunneling spectroscopy …

Observation Of In-Plane Magnetic Field Induced Phase Transitions In Fese, Jong Mok Ok, Chang Il Kwon, Yoshimitsu Kohama, Jung Sang You, Sun Kyu Park, Ji-Hye Kim, Y.J. Jo, E.S. Choi, Koichi Kindo, Woun Kang, Ki-Seok Kim, E. G. Moon, Alex Gurevich, Jun Sung Kim

Physics Faculty Publications

We investigate thermodynamic properties of FeSe under in-plane magnetic fields using torque magnetometry, specific heat, and magnetocaloric measurements. Below the upper critical field H_c2, we observed the field induced anomalies at H₁ ∼ 15 T and H₂ ∼ 22 T near H ∥ ab and below a characteristic temperature T* ∼ 2 K. The transition magnetic fields H₁ and H₂ exhibit negligible dependence on both temperature and field orientation. This contrasts to the strong temperature and angle dependence of H_c2, suggesting that these anomalies are attributed to the field induced phase transitions, …

Thermoelectric Porous Mof Based Hybrid Materials, Engelbert Redel, Helmut Baumgart

Electrical & Computer Engineering Faculty Publications

Porous hybrid materials and MOF (Metal-Organic-Framework) films represent modern designer materials that exhibit many requirements of a near ideal and tunable future thermoelectric (TE) material. In contrast to traditional semiconducting bulk TE materials, porous hybrid MOF templates can be used to overcome some of the constraints of physics in bulk TE materials. These porous hybrid systems are amenable for simulation and modeling to design novel optimized electron-crystal phonon-glass materials with potentially very high ZT (figure of merit) numbers. Porous MOF and hybrid materials possess an ultra-low thermal conductivity, which can be further modulated by phonon engineering within their complex porous …

Gold/Qds-Embedded-Ceria Nanoparticles: Optical Fluorescence Enhancement As A Quenching Sensor, Nader Shehata, Effat Samir, Ishac Kandas

Electrical & Computer Engineering Faculty Publications

This work focuses on improving the fluorescence intensity of cerium oxide (ceria) nanoparticles (NPs) through added plasmonic nanostructures. Ceria nanoparticles are fluorescent nanostructures which can emit visible fluorescence emissions under violet excitation. Here, we investigated different added plasmonic nanostructures, such as gold nanoparticles (Au NPs) and Cadmium sulfide/selenide quantum dots (CdS/CdSe QDs), to check the enhancement of fluorescence intensity emissions caused by ceria NPs. Different plasmonic resonances of both aforementioned nanostructures have been selected to develop optical coupling with both fluorescence excitation and emission wavelengths of ceria. In addition, different additions whether in-situ or post-synthesis have been investigated. We found …

Constraints On Parton Distribution Functions Imposed By Hadronic Experiments, Boting Wang

Physics Theses and Dissertations

The theoretical uncertainties of the Large Hadron Collider (LHC) observables are decreasing with the increasing statistics of the LHC experiments, and it is becoming more and more important to reduce the uncertainties in the knowledge of the nucleon structure. The latest LHC high-energy experiments, future experimental proposals, and computational tools are expected to enhance the knowledge of the nucleon structure. However, the global analysis that assesses their impact on Parton Distribution Functions (PDFs) knowledge is computationally expensive due to the corresponding large size of data. I developed a new approach that can make a quick preliminary evaluation to help the …