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Articles 1 - 30 of 1155
Full-Text Articles in Condensed Matter Physics
Glassy Magnetic Freezing Of Interacting Clusters In Materials Related To The Lk-99 Family, Serafim Teknowijoyo, Domenico Napoletani, Vahan Nikoghosyan, Armen Gulian
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 …
Electron Emission From Unactivated Gaas: Towards The Development Of Novel Sources Of Spin-Polarized Electrons, William Truslow Newman
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 …
Enhanced Superconductivity And Vortex Dynamics In Quasi-1d Tas2 Nanowires, Mathew Pollard, Visakha Ho, Clarissa Wisner, Eric W. Bohannan, Yew San Hor
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 …
Quantum Critical Behavior Of Diluted Quasi-One-Dimensional Ising Chains, Logan Sowadski, Thomas Vojta
Quantum Critical Behavior Of Diluted Quasi-One-Dimensional Ising Chains, Logan Sowadski, Thomas Vojta
Physics Faculty Research & Creative Works
(Formula presented.) (Formula presented.) is a unique magnetic material. It features bulk 3D magnetic order at low temperatures, but its quantum critical behavior in a magnetic field is well described by the 1D transverse-field Ising universality class. This behavior is facilitated by the structural arrangement of magnetic (Formula presented.) ions in nearly isolated zig-zag chains. In this work, we investigate the effect of random site dilution on the critical properties of such a quasi-1D quantum Ising system. To this end, we introduce an anisotropic site-diluted 3D transverse-field Ising model. We find that site dilution leads to unconventional activated scaling behavior …
Emergent Spin Fluctuation And Structural Metastability In Self-Intercalated Cr1+Xte2 Compounds, Clayton Conner, Ali Sarikhani, Theo Volz, Mathew Pollard, Mitchel Vaninger, Xiaoqing He, Steven Kelley, Jacob Cook, Avinash Sah, John Clark, Hunter Lucker, Cheng Zhang, Paul Miceli, Yew San Hor
Emergent Spin Fluctuation And Structural Metastability In Self-Intercalated Cr1+Xte2 Compounds, Clayton Conner, Ali Sarikhani, Theo Volz, Mathew Pollard, Mitchel Vaninger, Xiaoqing He, Steven Kelley, Jacob Cook, Avinash Sah, John Clark, Hunter Lucker, Cheng Zhang, Paul Miceli, Yew San Hor
Physics Faculty Research & Creative Works
Intercalated van der Waals (vdW) magnetic materials host unique magnetic properties due to the interplay of competing interlayer and intralayer exchange couplings, which depend on the intercalant concentration within the van der Waals gaps. Magnetic vdW compound chromium telluride, (Formula presented.), has demonstrated rich magnetic phases at various Cr concentrations, such as the coexistence of ferromagnetic and antiferromagnetic phases in (Formula presented.) (equivalently, (Formula presented.)). The compound is created by intercalating 0.25 Cr atom per unit cell within the van der Waals gaps of (Formula presented.). In this work, we report a notably increased Curie Temperature and an emergent in-plane …
Effects Of Radiation Type On Charge Transport In Aged Polymers, Zachary J. Gibson, Jr Dennison, Virginie Griseri
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
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. …
Harnessing Coherent-Wave Control For Sensing Applications, Pablo Jara, Arthur Goetschy, Hui Cao, Alexey Yamilov
Harnessing Coherent-Wave Control For Sensing Applications, Pablo Jara, Arthur Goetschy, Hui Cao, Alexey Yamilov
Physics Faculty Research & Creative Works
Imaging techniques such as functional near-infrared spectroscopy and diffuse optical tomography (DOT) achieve deep, noninvasive sensing in turbid media; however, they are constrained by the photon budget, as most of the injected light is lost to scattering before reaching the detector. Wavefront shaping (WFS) can enhance signal strength via interference at specific locations within scattering media, enhancing light-matter interactions and potentially extending the penetration depth of these techniques. Interpretation of the resulting measurements relies on knowing the optical sensitivity - the relationship between changes in the detected signals and perturbations at a specific location inside the medium; however, conventional diffusion-based …
Universal Crackling Noise Links Plasticity In Nanoindentation With Compression In Metallic Glasses, Jordan Sickle, Wesley H. Higgins, Kerry A. Baker, Mayisha Nakib, Xiaojun Gu, George M. Pharr, Wendelin Wright, Karin A. Dahmen
Universal Crackling Noise Links Plasticity In Nanoindentation With Compression In Metallic Glasses, Jordan Sickle, Wesley H. Higgins, Kerry A. Baker, Mayisha Nakib, Xiaojun Gu, George M. Pharr, Wendelin Wright, Karin A. Dahmen
Faculty Journal Articles
For decades, compression tests have been a standard method for identifying materials properties. However, these tests are slow, destructive, and require fabricating multiple potentially expensive bulk samples. Nanoindentation is fast, almost non-destructive, and requires only a single sample, to which large numbers of indents can be applied. Furthermore, nanoindentation is widely applicable, even to materials that are too brittle for traditional compression tests. Here, we show that nanoindentation is sufficient for extracting much of the same information that is measured in traditional sample compression tests in metallic glasses. The dynamics and statistics of the plasticity of two types of metallic …
Electron Yields Of Lunar Regolith Simulant Layers, Christopher Vega, Matthew Robertson, Thomas Keaton, Heather Allen, Jr Dennison
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
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 …
Time-Evolved Constant Voltage Conductivity Measurements Of Common Spaceborne Polymeric Materials, Brian Wood, David King, Jr Dennison
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 …
Ferroelectricity And Multiferroicity In Ultrathin Films Of Unconventional Transition Metal Oxide, Xin Li
Ferroelectricity And Multiferroicity In Ultrathin Films Of Unconventional Transition Metal Oxide, Xin Li
Department of Physics and Astronomy: Dissertations, Theses, and Student Research
Ferroic orders of transition metal oxides, such as ferroelectricity and ferromagnetism, are determined by the intercoupling between spin, charge, lattice. Consequently, ferroic epitaxial thin films have attracted wide interest due to the profuse novel phenomena and the great application potentials for modern electronics. However, the mainstream of the study for transition metal oxides has focused on perovskite structure, limiting the understanding and discovery of novel phenomena associate with ferroic orders. In this thesis, the epitaxial films of hexagonal rare-earth ferrites (h-RFeO3) and fluorite-structure hafnia oxide (HfO2) are studied comprehensively, providing new experimental and theoretic …
Creasing In Thick Hemispherical Shells As A Model For Foveal Formation, Indigo Skye Peppard
Creasing In Thick Hemispherical Shells As A Model For Foveal Formation, Indigo Skye Peppard
Undergraduate Honors Theses
This research experimentally investigates creasing behavior on the inner surface of hemispherical shells with the ultimate goal of modelling the formation of the foveal pit, a sharp surface deformation present in the retina of the eye of many animals. Creasing is a phenomenon observed in hyperelastic materials and is characterized by sharply localized surface deformations that appear at ~35% compressive strain. The foveal pits of anoles (small iguanian lizards) are funnel-shaped and resemble creases when cut along the central axis. Furthermore, during foveal pit formation the anole eye contracts around 35% along this same axis. Given these similarities we believe …
Low-Field Magnetoresistance In Nanocomposites Of La₀.₇Sr₀.₃Mno₃ And Metal Oxides, Nicholas K. Thiel-Hudson
Low-Field Magnetoresistance In Nanocomposites Of La₀.₇Sr₀.₃Mno₃ And Metal Oxides, Nicholas K. Thiel-Hudson
University Scholar Projects
Pure La0.7Sr0.3MnO3 (LSMO) exhibits colossal magnetoresistance (CMR) with large applied magnetic field over a narrow temperature range (intrinsic behavior), limiting its application to narrow temperature ranges. In contrast, the extrinsic CMR effect originates from inhomogeneities at larger length scales, such as grain boundaries and phase separation, where the structural features act as tunneling barriers, leading to a low-field magnetoresistance (LFMR) response, thereby expanding the application of LSMO into the low-field regime over a broader temperature range. In this work, the magnetotransport behavior of pure LSMO thin film is compared to the composite layered heterostructures of …
Young Professionals, Zachary Gibson
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.”
Spectral Width Of Maximum Deposition Eigenchannels In Diffusive Media, Rohin E. Mcintosh, Arthur Goetschy, Nicholas Bender, Alexey Yamilov, Chia Wei Hsu, Hasan Yllmaz, Hui Cao
Spectral Width Of Maximum Deposition Eigenchannels In Diffusive Media, Rohin E. Mcintosh, Arthur Goetschy, Nicholas Bender, Alexey Yamilov, Chia Wei Hsu, Hasan Yllmaz, Hui Cao
Physics Faculty Research & Creative Works
The maximum deposition eigenchannel provides the largest possible power delivery to a target region inside a diffusive medium by optimizing the incident wavefront of a monochromatic beam. It originates from constructive interference of scattered waves, which is frequency sensitive. We investigate the spectral width of the maximum deposition eigenchannels over a range of target depths using numerical simulations of a 2D diffusive system. Compared to tight focusing into the system, power deposition to an extended region is more sensitive to frequency detuning. The spectral width of enhanced delivery to a large target displays a rather weak, nonmonotonic variation with target …
Anderson Transition For Light In A Three-Dimensional Random Medium, Alexey Yamilov, Hui Cao, Sergey E. Skipetrov
Anderson Transition For Light In A Three-Dimensional Random Medium, Alexey Yamilov, Hui Cao, Sergey E. Skipetrov
Physics Faculty Research & Creative Works
We study Anderson transition for light in three dimensions by performing large-scale simulations of electromagnetic wave transport in disordered ensembles of perfect-electric-conducting spatially overlapping spheres. A mobility edge that separates diffusive transport and Anderson localization is identified, revealing a sharp transition from diffusion to localization for light. Critical behavior in the vicinity of the mobility edge is well described by a single parameter scaling law. The critical exponent is found to be consistent with the value known for the Anderson transition of the orthogonal universality class. Statistical distribution of total transmission at the mobility edge is described without any fit …
Quantum-Mechanical Definition Of The Classical Scalar Potential In Schrödinger-Pauli And Schrödinger Theory, Viraht Sahni
Quantum-Mechanical Definition Of The Classical Scalar Potential In Schrödinger-Pauli And Schrödinger Theory, Viraht Sahni
Publications and Research
According to the Bohr correspondence principle, the external temporal scalar potential in the classical equation of motion is replicated in quantum theory as a multiplicative operator. An equivalent quantum-mechanical definition of the scalar potential in Schrödinger-Pauli/Schrödinger theory is provided. The potential is a known universal functional of the wave function. At each instant of time, it is the work done in a conservative “classical” field representative of internal properties of the system: Pauli and Coulomb correlations, kinetic effects, the density, the Lorentz force, an internal magnetic component, and the current density response. The Hamiltonians are thus rewritten in a …
Characterizing 2d Materials Using Positron Impact Induced Electron Spectroscopy And Development Of A Novel Thin Film Zno Based Piezo-Photonic Detector For Cryogenic And Mems Applications, Pratyanik Sau
2024 Fall Honors Capstone Projects - Archive
Surface analytical techniques are essential for engineering nano-detectors allowing characterization of their chemical composition, electromechanical properties, and physical structure. In the first chapter, the positron impact-induced secondary electron (PIISE) energy spectra and yield from single-layer graphene (SLG) and multi-layer graphene (MLG) grown on a polycrystalline Cu substrate have been presented. In the second chapter, an extensive catalog of Positron Induced Auger Spectra is presented to aid in the analysis of elemental composition of various materials. Additionally, in the third chapter, a novel detection scheme utilizing the piezo-pyroelectric properties of Zinc Oxide (ZnO) thin films have been demonstrated for its application …
Multiphase Electrochemical Li-Ion Intercalation In Iron Selenite: Evidence Of Fe³⁺/⁴⁺ Redox And Single-Crystal-To-Single-Crystal Topochemical Transformation During Chemical Lithiation, Sutapa Bhattacharya, Aleksandr V. Chernatynskiy, Amitava Choudhury
Multiphase Electrochemical Li-Ion Intercalation In Iron Selenite: Evidence Of Fe³⁺/⁴⁺ Redox And Single-Crystal-To-Single-Crystal Topochemical Transformation During Chemical Lithiation, Sutapa Bhattacharya, Aleksandr V. Chernatynskiy, Amitava Choudhury
Physics Faculty Research & Creative Works
An iron selenite-based cathode compound, LiFe(SeO3)2, is synthesized via a simple hydrothermal route. The bulk purity of the compound is confirmed by powder X-ray diffraction (PXRD), Mössbauer spectroscopy, and Fourier transform infrared spectroscopy (FTIR). The crystal structure determined from the single-crystal X-ray diffraction and Rietveld refinement of synchrotron PXRD data perfectly matches the previously reported structure in the I4̅2d space group. The crystal structure is built up of edge-sharing of FeO6 octahedra and LiO4 tetrahedra interconnected by SeO3 trigonal pyramidal units, forming a three-dimensional open framework network with channels through all three axes. …
Insulator-To-Metal Transition And Isotropic Gigantic Magnetoresistance In Layered Magnetic Semiconductors, Gokul Acharya, Bimal Neupane, Chia-Hsiu Hsu, Xian P. Yang, David Graf, Eun Sang Choi, Krishna Pandey, Md Rafique Un Nabi, Santosh Karki Chhetri, Rabindra Basnet, Sumaya Rahman, Jian Wang, Zhengxin Hu, Bo Da, Hugh O.H. Churchill, Guoqing Chang, M. Zahid Hasan, Yuanxi Wang, Jin Hu
Insulator-To-Metal Transition And Isotropic Gigantic Magnetoresistance In Layered Magnetic Semiconductors, Gokul Acharya, Bimal Neupane, Chia-Hsiu Hsu, Xian P. Yang, David Graf, Eun Sang Choi, Krishna Pandey, Md Rafique Un Nabi, Santosh Karki Chhetri, Rabindra Basnet, Sumaya Rahman, Jian Wang, Zhengxin Hu, Bo Da, Hugh O.H. Churchill, Guoqing Chang, M. Zahid Hasan, Yuanxi Wang, Jin Hu
Physics Faculty Publications and Presentations
Magnetotransport, the response of electrical conduction to external magnetic field, acts as an important tool to reveal fundamental concepts behind exotic phenomena and plays a key role in enabling spintronic applications. Magnetotransport is generally sensitive to magnetic field orientations. In contrast, efficient and isotropic modulation of electronic transport, which is useful in technology applications such as omnidirectional sensing, is rarely seen, especially for pristine crystals. Here a strategy is proposed to realize extremely strong modulation of electron conduction by magnetic field which is independent of field direction. GdPS, a layered antiferromagnetic semiconductor with resistivity anisotropies, supports a field-driven insulator-to-metal transition …
Three-Dimensional Printing Limitations Of Polymers Reinforced With Continuous Stainless Steel Fibres And Curvature Stiffness, Alison J. Clarke, Andrew N. Dickson, Vladimir Milosavljevic, Denis P. Dowling
Three-Dimensional Printing Limitations Of Polymers Reinforced With Continuous Stainless Steel Fibres And Curvature Stiffness, Alison J. Clarke, Andrew N. Dickson, Vladimir Milosavljevic, Denis P. Dowling
Articles
This study investigates the printability limitations of 3D-printed continuous 316L stainless steel fibre-reinforced polymer composites obtained using the Materials Extrusion (MEX) technique. The objective was to better understand the geometric printing limitations of composites fabricated using continuous steel fibres, based on a combination of bending stiffness testing and piezoresistive property studies. The 0.5 mm composite filaments used in this study were obtained by co-extruding polylactic acid (PLA), with a 316 L stainless steel fibre (SSF) bundle. The composite printability limitations were evaluated by the printing of a series of ’teardrop’ shaped geometries with angles in the range from 5◦ to …
Modeling Permittivity Measurements Of Thin Film Materials Versus Film Thickness, Jr Dennison, Cameron Eggleston
Modeling Permittivity Measurements Of Thin Film Materials Versus Film Thickness, Jr Dennison, Cameron Eggleston
Journal Articles
Measured permittivity of thin film polymeric samples were substantially less for thin samples, asymptotically approaching bulk values above ~500 μm. For ~25 μm samples the observed permittivities were as much as 50% less than for bulk measurements. This behavior has been studied for four common homogeneous polymeric materials for sample thickness in the range of ~10 μm to > 1000 μm. To quantify these observations, an empirical single-parameter model was developed to correct measured permittivity of thin samples based on an effective stray capacitance in series with the samples to compensate for effects attributed to instrumentation.
Substrate Interference And Strain In The Second-Harmonic Generation From Mose2 Monolayers, Sudeep Puri, Sneha Patel, Jose Luis Cabellos, Luis Enrique Rosas-Hernandez, Kaitlin Reynolds, Hugh O.H. Churchill, Salvador Barraza-Lopez, Bernardo S. Mendoza, Hiroyuki Nakamura
Substrate Interference And Strain In The Second-Harmonic Generation From Mose2 Monolayers, Sudeep Puri, Sneha Patel, Jose Luis Cabellos, Luis Enrique Rosas-Hernandez, Kaitlin Reynolds, Hugh O.H. Churchill, Salvador Barraza-Lopez, Bernardo S. Mendoza, Hiroyuki Nakamura
Physics Faculty Publications and Presentations
Nonlinear optical materials of atomic thickness, such as non-centrosymmetric 2H transition metal dichalcogenide monolayers, have a second-order nonlinear susceptibility (χ(2)) whose intensity can be tuned by strain. However, whether χ(2) is enhanced or reduced by tensile strain is a subject of conflicting reports. Here, we grow high-quality MoSe2 monolayers under controlled biaxial strain created by two different substrates and study their linear and nonlinear optical responses with a combination of experimental and theoretical approaches. Up to a 15-fold overall enhancement in second-harmonic generation (SHG) intensity is observed from MoSe2 monolayers grown on SiO2 when …
Settingsorder Article Reprints Open Accessarticle A Model To Account For The Effects Of Load Ratio And Hydrogen Pressure On The Fatigue Crack Growth Behavior Of Pressure Vessel Steels, Ashok Saxena, Kip O. Findley
Settingsorder Article Reprints Open Accessarticle A Model To Account For The Effects Of Load Ratio And Hydrogen Pressure On The Fatigue Crack Growth Behavior Of Pressure Vessel Steels, Ashok Saxena, Kip O. Findley
Mechanical Engineering Faculty Publications and Presentations
A phenomenological model for estimating the effects of load ratio R and hydrogen pressure PH2 on the hydrogen-assisted fatigue crack growth rate (HA-FCGR) behavior in the transient and steady-state regimes of pressure vessel steels is described. The "transient regime" is identified with crack growth within a severely embrittled zone of intense plasticity at the crack tip. The "steady-state" behavior is associated with the crack growing into a region of comparatively lower hydrogen concentration located further away from the crack tip. The model treats the effects of R and PH2 as being functionally separable. In the transient …
Surface Patterning On Zirconia Dental Implants Via Laser-Induced Shockwave Imprinting, Inomjon Majidov
Surface Patterning On Zirconia Dental Implants Via Laser-Induced Shockwave Imprinting, Inomjon Majidov
Masters Theses & Specialist Projects
Zirconia is rapidly becoming a preferred alternative to titanium in dental applications, primarily due to its aesthetic resemblance to natural teeth. This material’s tooth-like color avoids the aesthetic issues associated with the grey metal tint of titanium implants. Additionally, zirconia is hypoallergenic, making it an ideal choice for patients with metal sensitivities or allergies. Despite these advantages, zirconia generally exhibits lower biocompatibility and osseointegration compared to titanium implants. This study investigates laser-assisted, controlled imprinting technique on zirconia surfaces to enhance these properties. Our research used zirconia pellets, produced from powdered monoclinic zirconia pressed in a pellet press machine. Two methods …
Synthesis And Characterization Of A Zirconium (Zr) Thin Film On Si(100) Via Pulsed Laser Deposition, Zikrulloh Khuzhakulov
Synthesis And Characterization Of A Zirconium (Zr) Thin Film On Si(100) Via Pulsed Laser Deposition, Zikrulloh Khuzhakulov
Masters Theses & Specialist Projects
This study investigates the synthesis and characterization of zirconium (Zr) thin films deposited on Si(100) substrates using pulsed laser deposition (PLD). The effects of two laser wavelengths (1064 nm and 532 nm), various substrate temperatures (25 °C, 300 °C, and 500 °C), and different laser fluences (0.25, 0.5, 1.0 J/cm²) on the properties of the Zr films were examined. Results indicated that smoother films were achieved with the 1064 nm wavelength, while surface roughness increased with higher fluences. Optimal crystalline films were obtained at a substrate temperature of 300 °C for both wavelengths. X-ray diffraction (XRD), scanning electron microscopy (SEM), …
Modeling Study Of Si3N4 Waveguides On A Sapphire Platform For Photonic Integration Applications, Diandian Zhang, Shui-Qing Yu, Gregory J. Salamo, Richard A. Soref, Wei Du
Modeling Study Of Si3N4 Waveguides On A Sapphire Platform For Photonic Integration Applications, Diandian Zhang, Shui-Qing Yu, Gregory J. Salamo, Richard A. Soref, Wei Du
Electrical Engineering and Computer Science Faculty Publications and Presentations
Sapphire has various applications in photonics due to its broadband transparency, high-contrast index, and chemical and physical stability. Photonics integration on the sapphire platform has been proposed, along with potentially high-performance lasers made of group III–V materials. In parallel with developing active devices for photonics integration applications, in this work, silicon nitride optical waveguides on a sapphire substrate were analyzed using the commercial software Comsol Multiphysics in a spectral window of 800~2400 nm, covering the operating wavelengths of III–V lasers, which could be monolithically or hybridly integrated on the same substrate. A high confinement factor of ~90% near the single-mode …
Twist-Assisted All-Antiferromagnetic Tunnel Junction In The Atomic Limit, Yullang Chen, Kartik Samanta, Naafls A. Shahed, Haojle Zhang, Chi Fang, Arthur Ernst, Evgeny Y. Tsymbal, Stuart S.P. Parkin
Twist-Assisted All-Antiferromagnetic Tunnel Junction In The Atomic Limit, Yullang Chen, Kartik Samanta, Naafls A. Shahed, Haojle Zhang, Chi Fang, Arthur Ernst, Evgeny Y. Tsymbal, Stuart S.P. Parkin
Nebraska Center for Materials and Nanoscience: Faculty Publications
Antiferromagnetic spintronics1,2 shows great potential for high-density and ultrafast information devices. Magnetic tunnel junctions (MTJs), a key spintronic memory component that are typically formed from ferromagnetic materials, have seen rapid developments very recently using antiferromagnetic materials3,4. Here we demonstrate a twisting strategy for constructing all-antiferromagnetic tunnel junctions down to the atomic limit. By twisting two bilayers of CrSBr, a 2D antiferromagnet (AFM), a more than 700% nonvolatile tunnelling magnetoresistance (TMR) ratio is shown at zero field (ZF) with the entire twisted stack acting as the tunnel barrier. This is determined by twisting two CrSBr monolayers for which the TMR …