Condensed Matter Physics Commons^™

Systematic Methodologies For Magnetic Materials Design, Andres Tellez Mora

Graduate Theses, Dissertations, and Problem Reports (ETD)

Understanding and predicting the magnetic behavior of materials from first principles is one of the central challenges in condensed matter physics. This dissertation presents a systematic framework that bridges ab initio calculations, many-body physics, and effective spin models to analyze magnetic materials in particular, but also more general quantum systems. Starting from the electron many-body Hamiltonian and the second quantization formalism, we derive Density Functional Theory (DFT) and explain how magnetic properties emerge from exchange interactions and can be interpreted as perturbations to the magnetization density. To capture these effects efficiently, we construct Heisenberg models from first principles using the …

Effect Of Temperature And Rhenium Content In Precipitates On Dispersion Hardening Of Tungsten, Yulia R. Sharapova, Arseny M. Kazakov, Elena A. Korznikova, Alexandr Zinovev, Dmitry Terentyev, Sergey V. Dmitriev

Karbala International Journal of Modern Science

Tungsten (W) is being developed as a plasma-facing material for fusion reactors, where it is subjected to MeV neutron irradiation, low-energy helium isotope particles, and high temperatures. These conditions lead to the formation of point defects, dislocation loops, voids, and transmutation into rhenium (Re) and osmium (Os), which form precipitates that significantly impact dislocation motion and increase hardness. This study uses molecular dynamics modeling to examine the interaction between an edge dislocation and Re-rich particles of various stoichiometries, specifically coherent bcc-phase particles and noncoherent σ-phase precipitates. Results show that shear stress increases by approximately 20-40% with larger particle size (3-5 …

Ge/Sige Quantum Wells: Material For The Post-Moore Era, Troy Alexander Hutchins-Delgado

Optical Science and Engineering ETDs

This dissertation demonstrates high-quality germanium quantum wells on a 200 mm silicon wafer platform, enabling novel device possibilities. Partnering with a commercial silicon-germanium epitaxy supplier, we obtained shallow, undoped germanium quantum wells with high-crystalline quality, confirmed through x-ray diffraction, secondary ion mass spectroscopy, high-resolution scanning transmission electron microscopy, and energy dispersive x-ray spectroscopy. Hall bar devices fabricated on single quantum wells revealed that surface preparation can tune transport properties while maintaining peak mobilities around 10⁵ cm²V⁻¹s⁻¹. Manganese-germanide spintronic contacts were integrated via solid-state reaction, with contact quality assessed through Schottky diodes, transfer length …

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 …

Single-Shot Mev-Resolution Hard X-Ray Spectrograph For Cavity-Based X-Ray Free Electron Laser, Keshab Kauchha

Dissertations

The Cavity-Based X-ray Free Electron Laser (CBXFEL) is a possible future direction in the development of fully coherent hard X-ray sources of high spectral brilliance, a narrow spectral bandwidth of ≃ 1 − 100 meV, and a high repetition rate of ≃ 1 MHz. A diagnostic tool is required to measure CBXFEL spectra with a meV resolution on a shot-to-shot basis.

The CBXFEL hard X-ray spectrograph is designed to image 9.831 keV X-rays in a ≃ 200 meV spectral window and with a spectral resolution of a few meV using an LCLS XFEL (Linac Coherent Light Source X-ray Free Electron …

Charge Transport In Two Dimensional Systems With Arbitrary Rashba And Dresselhaus Interactions, Abhishek Khanal

All Dissertations

In this thesis we discuss two different transport phenomena that occur in a two-dimensional electron system endowed with linear Rashba and Dresselhaus spin-orbit interactions of arbitrary values. First, in a semiclassical formalism we calculate the non-linear charge currents that appear in response to the simultaneous application of in-plane electric and magnetic fields. Working in a rotated system of coordinates that introduces $\alpha \pm \beta$ as effective couplings on perpendicular directions, we formulate a transport theory that relies on a second order distribution function derived in a local energy approximation and on chiral dependent relaxation times to show that the currents …

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

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 …

Experimental Characterization, Computational Investigation, And Structure-Property–Activity Relationship Studies Of Nickel Ferrite Nanostructures, Ali Ben Ahmed

Polytechnic Journal

Intending to predict the multifunctionality of Nickel ferrite in several technological and medical fields, we have prepared nickel ferrite nanostructure by coprecipitation method. X-ray Diffraction (XRD) is used to determine the crystalline structure and phase composition of materials by analyzing the pattern of X-rays scattered by the atoms within the material. Fourier Transform Infrared Spectroscopy (FTIR) provides information about a material's chemical bonds and functional groups by analyzing how it absorbs infrared light at various wavelengths. Scanning Electron Microscopy (SEM) offers high-resolution images of the material's surface morphology and texture by scanning it with a focused beam of electrons. Transmission …

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

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

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 …

First-Principles Calculations Of Thermoelectric Properties Of Fe-Based Full- Heusler Fe2cusi, Ai Nurlaela, Dwi Nanto, Anugrah Azhar, Elvan Yuniarti, Tony Kristiantoro, Dedi Dedi

Makara Journal of Science

A first-principle study using density functional theory (DFT) and Boltzmann transport was conducted to evaluate the thermoelectric (TE) properties of an Fe-based full-Heusler alloy. The compound studied is Fe₂CuSi with a Cu₂MnAl-type structure. The electronic properties of Fe₂CuSi were obtained using DFT calculations by running the Quantum ESPRESSO (QE) package. By contrast, TE properties, including electron thermal conductivity, electric conductivity, and Seebeck coefficient, were computed using a semi-empirical Boltzmann transport model solved through the BoltzTraP software at 50–1,500 K temperature range. The spin-orbit coupling effect on these properties was also evaluated, demonstrating notable effects …

Interplay Of Magnetic Impurities And Superconductivity In Topological Materials, Didier Ndengeyintwali

Dissertations, Theses, and Capstone Projects

The interplay of superconductivity and magnetism has been a long-standing topic of interest since the discovery of superconductivity. In recent years it has been shown that topological superconductivity, which has promising applications such as in topological quantum computing, could result from such interplay. Motivated by the later results I study the effect of magnetic impurities in superconducting doped topological insulators, such as Iron based topological superconductors. I show that topological character of parent materials could lead to modifications in the structure of magnetic impurity induced in-gap states. Moreover, the superconductivity induced interaction between magnetic impurities in doped topological insulator would …

Shear Viscosity Of Quasi One-Dimensional Bec Tubes And Entanglement Negativity Conditions, Camilla Polvara

Dissertations, Theses, and Capstone Projects

Shear Viscosity of Quasi One-dimensional BEC Tubes

We consider layered Bose-Einstein condensates interacting via contact intra-condensate interacions and dipolar inter-condensate potentials, both of which dominate intercondensate tunneling (which we neglect for simplicity). For this system, we compute the normal modes, we study its localization properties by numerically computing the inverse participation ratio, and we compute the inter-tube shear viscosity.

Entanglement Negativity Conditions

This project explores bounds on entanglement negativity using operator inequalities, building on the results of [1]. We are looking for a way to quantify entanglement, as an alternative to calculating the full negativity, which would otherwise require the …

Mg3sb2-Based Materials For Mid-Temperature Thermoelectric Application, Veera Prabhu K

Theses and Dissertations

Recently, there has been growing research in the scientific community regarding the conversion of heat flux into electricity, which has proven effective in mitigating energy crises. Solid-state thermoelectric (TE) devices use the Seebeck effect to efficiently convert waste heat into electricity. Traditional materials contain toxic, rare, and expensive elements like Lead, Tellurium, and Germanium that restrict large-scale production, commercialization, and practical utilization.

Recently, Mg3Sb2-based materials have been attractive due to their remarkable characteristics, including abundance, affordability, and environmental friendliness. Furthermore,n-type Mg3Sb2-based materials exhibit high TE performance because of their high band degeneracy in the conduction band minimum (CBM), and low …

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 P_H2 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 P_H2 as being functionally separable. In the transient …

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

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), …

Tuning Electronic Transport And Magnetic Properties Of Layered Magnetic Materials, Md Rafique Un Nabi

Graduate Theses and Dissertations

Two-dimensional magnetic materials (2DMMs) have gained significant interest due to their potential for novel physical phenomena and device applications. Mn_2-xZn_xSb, with its tunable magnetic properties and stable tetragonal layered structure, offers a rich platform for exploring these phenomena. The introduction of Zn into the Mn₂Sb lattice efficiently tunes magnetic and electronic properties, making it a compelling candidate for high-performance spintronic devices.

With this motivation, we synthesized Mn_2-xZn_xSb (0 ≤ x ≤ 1) single crystals using a flux method. Mn2Sb exhibits ferrimagnetic order below 550 K with antiparallel spins aligned along …