# Physics Commons™

Articles 1 - 30 of 259

## Full-Text Articles in Physics

Jan 2019

#### Tuning Of Layered Materials: Studies Of Craute4, Pdsn4 And Wte2, Na Hyun Jo

##### Graduate Theses and Dissertations

Layered materials are of great and growing interest for material scientists and condensed matter physicists, not only because of their possible applications but also because of the diverse and controllable ground states. In addition, tuning of layered materials through external fields, doping, or strain can lead to the emergence of novel phenomena. In this dissertation, the importance of the study of layered materials is emphasized in Chapter 1. Before getting into experimental results, the theoretical background and experimental methods, including growth of single crystals of selected layered materials, are introduced in Chapter 2 and Chapter 3. Chapters 4, 5 and ...

Symmetry Reduction In K − P Problems, Benjamin Sheller Jan 2019

#### Multiphysics Analysis Of Electrochemical And Electromagnetic System Addressing Lithium-Ion Battery And Permanent Magnet Motor, Abhishek Sarkar

##### Graduate Theses and Dissertations

Lithium-ion batteries are the leading energy storage technology in the electronic-driven society. With the need for portable, long-life electronics the demand for lithium batteries has escalated over the decade. Lithium-ion batteries show remarkable electrochemical characteristics, including but not limited to, long cycle-life, high cut-off voltages and high energy-density. However, lithium-ion cells are problematic to design due to their inherent thermal and/or mechanical instability. The objective of the current research framework is to establish the criteria causing thermo-mechanical failure of the battery systems, material properties effecting the performance, and model cycle-life degradation due to electrolyte loss by solid electrolyte interface ...

#### Measurement Of The Kaon Production Normalization In The Numi Target Using Uncontained Charged-Current Muon Neutrino Interactions In The Nova Far Detector, Jose Andres Sepulveda-Quiroz

##### Graduate Theses and Dissertations

NOvA is a long-baseline neutrino oscillation experiment that uses the NuMI beam from Fermilab.

Its physics goals include providing constraints to the neutrino mass hierarchy and the CP-violating phase $\delta$ by precision measurements of the electron (anti)neutrino

appearance in a muon (anti)neutrino beam.

Similarly, new limits on the values of $\sin^2{\theta_{23}}$ and $\Delta m^{2}_{32}$ will be achieved by measurements of the muon (anti)neutrino disappearance probabilities.

A combined analysis measurement will allow a better resolution of the $\theta_{23}$ octant.

The NuMI beam is produced by the collision of high energy protons ...

Pressure Effects On Magnetism And Superconductivity, Udhara Sampath Kaluarachchi Jan 2018

#### Pressure Effects On Magnetism And Superconductivity, Udhara Sampath Kaluarachchi

##### Graduate Theses and Dissertations

This thesis summarizes experimental work using high pressure as a tuning parameter in the study of selected correlated electron systems at low temperatures. This thesis contains 8 chapters and 2 appendices. After giving the introduction in Chapter 1, experimental techniques are discussed in Chapter 2. Chapters 3 and 5 are devoted to pressure studies of ferromagnetic materials. In ferromagnetic systems, the appearance of quantum criticality is avoided either by a change of the second order transition to one of the first-order at a tricritical point or by the appearance of modulated, antiferromagnetic, phase. Chapter 3 summarizes the pressure study of ...

Jan 2018

#### Biophysics Of Cadherin Interactions And Junction Assembly, Omer Shafraz

##### Graduate Theses and Dissertations

Desmosomes are robust cell adhesion junctions that are composed of two transmembrane desmosomal cadherin proteins: desmoglein (Dsg) and desmocollin (Dsc). The extracellular regions of Dsc and Dsg form an adhesive interface between cells while their cytoplasmic tails links to the intracellular keratin filament network. This dissertation investigates how Dsc and Dsg assemble into desmosomes using single molecule force measurements with an Atomic Force Microscope (AFM) and cell-based fluorescence assays. In Chapter 1, I give a brief over view of the content of this dissertation and the principles of AFM force measurements. In Chapter 2, I characterize the binding of isoform ...

Constraints On Neutrino Oscillation Parameters With The Nova Experiment, Erika Cantano-Mur Jan 2018

#### Constraints On Neutrino Oscillation Parameters With The Nova Experiment, Erika Cantano-Mur

##### Graduate Theses and Dissertations

NOvA is a long-baseline neutrino oscillation experiment, which consists of two finely-segmented liquid-scintillator detectors

operating 14 mrad off-axis from the NuMI muon neutrino beam. With an 810 km baseline, the combined measurements of muon neutrino disappearance and electron neutrino appearance allow the determination of neutrino oscillation unknowns, namely the mass hierarchy, the octant of the largest neutrino mixing angle, and the CP violating phase.

In this dissertation, I present the joint analysis of $\nu_\mu\to\nu_\mu$ and $\nu_mu\to\nu_e$ oscillation data with an exposure of

$8.85\times10^{20}$ protons on target on the 14 kton detector ...

Structural And Magnetic Studies On Srco2as2 And Ca(Co1−Xfex)Yas2 Compounds Using X-Ray And Neutron Scattering, Wageesha Tharuki Jayasekara Jan 2018

#### Structural And Magnetic Studies On Srco2as2 And Ca(Co1−Xfex)Yas2 Compounds Using X-Ray And Neutron Scattering, Wageesha Tharuki Jayasekara

##### Graduate Theses and Dissertations

The AM2X2 (A = alkaline, alkaline earth or rare earth element M = transition metals, and X = pnictogen), 122 type ternary compounds acquire overwhelming attention due to their richness of the correlations and competition between the lattice, electronic, and magnetic degrees of freedom. Properly controlling those correlations can lead to a variety of novel ground states including different crystallographic structures, magnetically ordered states, or high-temperature superconductors. This thesis summarizes experimental work using high pressure and element substitution as tuning parameters in the study of selected 122 systems to understand their diverse structural and magnetic properties and interplay between the magnetism and electronic ...

#### Biodetection And Biointerface Based On Nanostructured Aluminum Oxide (Nao): From Fluorescence Enhancement To Ms Effect On Single Neural Cells, Xiangchen Che

##### Graduate Theses and Dissertations

Anodic aluminum oxide (AAO) has been investigated and utilized in numerous products for almost a century. But the rapidly increasing interest in nanoscale materials and their outstanding properties has propelled nanoporous AAO to be used as a substrate for sensors and biosensors. Fluorescence-based biosensors are one type of optical biosensors which are very popular for detecting a variety of targets (DNA, RNA, glucose, enzyme, bacteria, etc.). The recent discovery of AAO fluorescence enhancement effect makes AAO more attractive since it has the great potential to be used in biosensing field to improve the sensor sensitivity. However, the mechanism of the ...

Growth, Properties And Magnetism Of Cakfe4as4, William Richard Meier Jan 2018

#### Growth, Properties And Magnetism Of Cakfe4as4, William Richard Meier

##### Graduate Theses and Dissertations

CaKFe4As4 is a new stoichiometric member of the iron-based superconductors (FeSCs) which is a superconductor below 35 K. In this thesis I outline how single crystals of this material are grown for the first time and their basic properties. I discuss how substituting Ni or Co for Fe stabilizes antiferromagnetism at the expense of superconductivity. I reveal how the crystal structure of CaKFe4As4 leads to the observed hedgehog spin-vortex crystal magnetic order instead of the magnetic structures adopted by the other FeSCs. Finally, I propose a series of new magneto-elastic couplings in this new magnetic structure.

Exotic Phases In Strongly Correlated Materials, Guanghua Zhang Jan 2018

#### Exotic Phases In Strongly Correlated Materials, Guanghua Zhang

##### Graduate Theses and Dissertations

In strongly correlated materials, the electron-electron interaction is much stronger than the kinetic energy and plays a determining role in the properties of such materials. The strong electron-electron interaction often gives rise to exotic physical phenomena, such as high-temperature superconductivity, quantum Hall effects, Mott insulators, heavy fermion systems, and quantum criticality. There is no unified and effective approach to understand the physics in different materials, however, many of the same techniques generalize to different scenarios. In this thesis, we will discuss two types of exotic phases: the nematic order above the double-stripe magnetism, and hastatic order which originates from two-channel ...

Jan 2018

#### Interface Energy Transport Of Two-Dimensional (2d) Mos2, Pengyu Yuan

##### Graduate Theses and Dissertations

The bottleneck of most modern technologies and energy solutions has been attributed to the thermal problems at the nanoscale. Especially, the thermal transport across interfaces and in-plane direction can significantly influence the overall performance of 2D nanosystems. So accurate thermal-physical characterization of the 2D materials is very important for both fundamental research and industrial applications.

Focusing on 2D mechanically exfoliated MoS2, at first, we conduct a detailed temperature and laser power dependent micro-Raman spectroscopy study of FL MoS2 (4.2 to 45 nm thick) on c-Si substrate. We measured the interfacial thermal resistance (R) at room temperature decreases with increased ...

#### Study Of The Energy Gap Structure In Iron-Based Superconductors Using London Penetration Depth And Controlled Artificial Disorder, Serafim Teknowijoyo

##### Graduate Theses and Dissertations

A combination of London penetration depth and artificial disorder was used to probe the energy gap structure and symmetry of a few members of the iron-based superconductor systems. Information regarding the gap structure and symmetry is an important clue which helps uncover the mechanism behind the unconventional, non-BCS-type superconductors. We used the tunnel-diode resonator method to do London penetration depth measurements with high precision down to 50~mK base temperature. The disorder is introduced by electron irradiation, which was performed at the SIRIUS facility in Ecole Polytechnique (Palaiseau France) to produce point-like disorder in the materials of study. Non-magnetic defects ...

#### Studies Of Spin Dynamics In 122 Transition Metal Arsenides Using Inelastic Neutron Scattering Technique, Aashish Sapkota

##### Graduate Theses and Dissertations

The diverse physical properties and interrelationship between various ground states offer a rich physics to explore in 122 $A$TM$_2$As$_2$ ($A =$Ca, Sr, Ba and TM = 3d transition metals). This thesis discusses three examples of the 122 $A$TM$_2$As$_2$ compounds, TM = Fe, Co and Mn, where the focus is to understand their diverse magnetic properties and interplay between the magnetism and electronic properties including superconductivity. Therefore, the spin dynamics (spin fluctuations) of these compounds were studied using inelastic neutron scattering technique.

CaFe$_2$As$_2$ and the derived compounds are the first system discussed ...

#### Search For New Long-Lived Hadronically-Decaying Particles Produced In Association With A Z Boson With The Atlas Detector At The Lhc, Michael Werner

##### Graduate Theses and Dissertations

The standard model fails to fully explain several observations about the universe, one of the

prominent ones is the existence of dark matter. Many different models have been proposed for

dark matter candidates, but it is possible that the dark matter itself will remain elusive. Dark

sector models contain both dark matter and a new force which acts upon it. The force-carrying

boson of this dark sector may be more easily detected than dark matter itself. These models

contain a number of free parameters, some combinations of which result in the dark sector

particle being long-lived but unstable, resulting in ...

#### Structures And Dynamics Investigation Of Phase Selection In Metallic Alloy Systems, Lin Yang

##### Graduate Theses and Dissertations

Different phases of metallic alloys have a wide range of applications. However, the driving mechanisms of the phase selections can be complex. For example, the detailed pathways of the phase transitions in the devitrification process still lack a comprehensive interpretation. So, the understanding of the driving mechanisms of the phase selections is very important.

In this thesis, we focus on the study of the Al-Sm and other related metallic alloy systems by simulation and experiment. A procedure to evaluate the free energy has been developed within the framework of thermodynamic integration, coupled with extensive GPU-accelerated molecular dynamics (MD) simulations; The ...

Jan 2018

#### Nuclear Magnetic Resonance Studies Of Magnetic Fluctuations And Nematic Order In Iron-Based Superconductors, Paul Waymouth Wiecki

##### Graduate Theses and Dissertations

This thesis illustrates the use of the nuclear magnetic resonance (NMR) technique as a local probe for the study of static and dynamic magnetism in the iron-based superconductors.

First, a Korringa ratio analysis of 59Co and 75As NMR data reveals the existence of ferromagnetic (FM) spin fluctuations in SrCo2As2 and the hole- and electron-doped BaFe2As2 families of iron-pnictide superconductors. The analysis further shows that the FM fluctuations compete with AFM fluctuations to suppress superconductivity in these materials. The FM fluctuations are thus a crucial ingredient to understanding the variability of the superconducting transition temperature (Tc) and the shape of the ...

#### Design And Simulation Of A Miniature Cylindrical Mirror Auger Electron Energy Analyzer With Secondary Electron Noise Suppression, Jay A. Bieber

##### Graduate Theses and Dissertations

In the nanoscale metrology industry, there is a need for low-cost instruments, which have the ability to probe the structrure and elemental composition of thin films. This dissertation, describes the research performed to design and simulate a miniature Cylindrical Mirror Analyzer, (CMA), and Auger Electron Spectrometer, (AES). The CMA includes an integrated coaxial thermionic electron source. Electron optics simulations were performed using the Finite Element Method, (FEM), software COMSOL. To address the large Secondary Electron, (SE), noise, inherent in AES spectra, this research also included experiments to create structures in materials, which were intended to suppress SE backgound noise in ...

Manipulating Electromagnetic Waves With Enhanced Functionalities Using Nonlinear And Chiral Metamaterials, Sinhara Rishi Malinda Silva Nov 2017

#### Manipulating Electromagnetic Waves With Enhanced Functionalities Using Nonlinear And Chiral Metamaterials, Sinhara Rishi Malinda Silva

##### Graduate Theses and Dissertations

Metamaterials are artificial structures, which periodically arranged to exhibit fascinating electromagnetic properties, not existing in nature. A great deal of research in the field of metamaterial was conducted in a linear regime, where the electromagnetic responses are independent of the external electric or magnetic fields. Unfortunately, in linear regime the desired properties of metamaterials have only been achieved within a narrow bandwidth, around a fixed frequency. Therefore, nonlinearity is introduced into metamaterials by merging meta-atoms with well-known nonlinear materials. Nonlinear metamaterials are exploited in this dissertation to introduce and develop applications in microwave frequency with broadband responses. The nonlinearity was ...

#### Growth, Characterization, And Function Of Ferroelectric, Ferromagnetic Thin Films And Their Heterostructures, Mahesh Hordagoda

##### Graduate Theses and Dissertations

With recent trends in miniaturization in the electronics sector, ferroelectrics have gained popularity due to their applications in non-volatile RAM. Taking one step further researchers are now exploring multiferroic devices that overcome the drawbacks of ferroelectric (FE) and ferromagnetic (FM) RAM’s while retaining the advantages of both. The work presented in this dissertation focuses on the growth of FE and FM thin film structures. The primary goals of this work include, (1) optimization of the parameters in the pulsed laser deposition (PLD) of FE and FM films and their heterostructures, (2) development of a structure-property relation that leads to ...

Surfaces And Epitaxial Films Of Corundum-Structured Mixed Metal Oxides., Alan Richard Kramer Nov 2017

#### Surfaces And Epitaxial Films Of Corundum-Structured Mixed Metal Oxides., Alan Richard Kramer

##### Graduate Theses and Dissertations

Throughout the last half century of materials science, significant motivations came from, and still do, the industrial applications of these materials. Whether it is electronic, thermal, tribological or chemical in nature, the study of metals, semiconductors and insulators eventually reveals that the surface plays a significant part in the properties of these materials. Understanding metal terminations reveals often that an oxide is the stable state of the metallic surface in an ambient atmosphere and the ability to predict and control these oxides has led to significant strides forward in not just the metallic bulk but the oxide as well.

Here ...

Nov 2017

#### Application Of Metamaterials To Rf Energy Harvesting And Infrared Photodetection, Clayton M. Fowler

##### Graduate Theses and Dissertations

Techniques for adapting metamaterials for the improvement of RF energy harvesting and infrared photodetection are demonstrated using experimental and computer simulation methods. Two methods for RF energy harvesting are experimentally demonstrated and supported by computer simulation. In the first method, a metamaterial perfect absorber (MPA) is made into a rectenna capable of harvesting RF energy and delivering power to a load by soldering Schottky diodes onto connected split ring resonator (SRR) structures composing the planar metasurface of the perfect absorber. The metamaterial rectenna is accompanied by a ground plane placed parallel to it, which forms a Fabry-Perot cavity between the ...