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Complex Diffusion Monte-Carlo Method: Test By The Simulation Of The 2d Fermions, Bakhodir Abdullaev, Mirzayousuf Musakhanov, Atsushi Nakamura 2020 National University of Uzbekistan

Complex Diffusion Monte-Carlo Method: Test By The Simulation Of The 2d Fermions, Bakhodir Abdullaev, Mirzayousuf Musakhanov, Atsushi Nakamura

Bulletin of National University of Uzbekistan: Mathematics and Natural Sciences

On the base of the diffusion Monte-Carlo method we develop the method allowing to simulate the quantum systems with complex wave function. The method is exact and there are no approximations on the simulations of the module and the phase of the system's wave function. In our method averaged value of any quantity have no direct contribution from the phase of distribution function but only from the phase of the Green function of diffusion equation. We test the method by the simulations of the ground state of fermions in two-dimensional parabolic well. Anyons are used for the representation of ...


Tuning Of Charge Density Wave Transitions In Laauxsb2 By Pressure And Au Stoichiometry, Li Xiang, Dominic H. Ryan, Warren E. Straszheim, Paul C. Canfield, Sergey L. Bud’ko 2020 Iowa State University and Ames Laboratory

Tuning Of Charge Density Wave Transitions In Laauxsb2 By Pressure And Au Stoichiometry, Li Xiang, Dominic H. Ryan, Warren E. Straszheim, Paul C. Canfield, Sergey L. Bud’Ko

Ames Laboratory Accepted Manuscripts

Two charge density wave transition can be detected in LaAuSb2 at similar to 110 and similar to 90K by careful electrical transport measurements. Whereas control of the Au site occupancy in LaAuxSb2 (for 0.9 less than or similar to x less than or similar to 1.0) can suppress each of these transitions by similar to 80K, the application of hydrostatic pressure can completely suppress the lower transition by similar to 7.5kbar and the upper transition by similar to 17kbar. Clear anomalies in the resistance as well as the magnetoresistance are observed to coincide with the pressures at ...


Magnetism And Its Coexistence With Superconductivity In Cak(Fe0.949ni0.051)(4)As-4: Muon Spin Rotation/Relaxation Studies, Rustem Khasanov, Gediminas Simutis, Yurii G. Pashkevich, Tatyana Shevtsova, William R. Meier, Mingyu Xu, Sergey L. Bud’ko, Vladimir G. Kogan, Paul C. Canfield 2020 Paul Scherrer Institut

Magnetism And Its Coexistence With Superconductivity In Cak(Fe0.949ni0.051)(4)As-4: Muon Spin Rotation/Relaxation Studies, Rustem Khasanov, Gediminas Simutis, Yurii G. Pashkevich, Tatyana Shevtsova, William R. Meier, Mingyu Xu, Sergey L. Bud’Ko, Vladimir G. Kogan, Paul C. Canfield

Ames Laboratory Accepted Manuscripts

The magnetic response of CaK(Fe0.949Ni0.051)(4)As-4 was investigated by means of the muon spin rotation/relaxation. The long-range commensurate magnetic order sets in below the Neel temperature T-N = 50.0(5) K. The density-functional theory calculations have identified three possible muon stopping sites. The experimental data were found to be consistent with only one type of magnetic structure, namely, the long-range magnetic spin-vortex-crystal order with the hedgehog motif within the ab plane and the antiferromagnetic stacking along the c direction. The value of the ordered magnetic moment at T approximate to 3 K was estimated to ...


The Electronic Properties Of The Quasi-One-Dimensional Transition Metal Trichalcogenides: Tis3 And Zrs3, Simeon Gilbert 2020 University of Nebraska-Lincoln

The Electronic Properties Of The Quasi-One-Dimensional Transition Metal Trichalcogenides: Tis3 And Zrs3, Simeon Gilbert

Theses, Dissertations, and Student Research: Department of Physics and Astronomy

The transition metal trichalcogenides are a class of materials formed by 1D chains of covalently bound MX3 (M=Ti, Zr, Hf, Ta, Nb; X=S, Se, Te) trigonal prisms which are held together by weak van der Waals forces to form 2D sheets. Because of their superior edge termination, these materials suppress edge scattering effects that plague other two-dimensional materials thus enabling devices scaling to widths below 10 nm. Furthermore, this quasi-one-dimensional structure results in highly anisotropic electronic and optical properties which were examined through angle resolved photoemission spectroscopy and scanning photocurrent microscopy. These measurements show that the hole ...


Emulating Condensed Matter Systems In Classical Wave Metamaterials, Matthew Weiner 2020 The Graduate Center, City University of New York

Emulating Condensed Matter Systems In Classical Wave Metamaterials, Matthew Weiner

Dissertations, Theses, and Capstone Projects

One of the best tools we have for the edification of physics is the analogy. When we take our classical set of states and dynamical variables in phase space and treat them as vectors and Hermitian operators respectively in Hilbert space through the canonical quantization, we lose out on a lot of the intuition developed with the previous classical physics. With classical physics, through our own experiences and understanding of how systems should behave, we create easy-to-understand analogies: we compare the Bohr model of the atom to the motion of the planets, we compare electrical circuits to the flow of ...


Wave Propagation In Random And Topological Media, Yuhao Kang 2020 The Graduate Center, City University of New York

Wave Propagation In Random And Topological Media, Yuhao Kang

Dissertations, Theses, and Capstone Projects

This thesis discusses wave propagation in two kinds of systems, random media and topological insulators. In a disordered system, the wave is randomized by multiple scattering. The scattering matrix and associated delay times are powerful tools with which to describe wave transport. We discuss the relation among the Wigner time, the transmission time, and energy density in a lossless or lossy system. We propose the zeros of the transmission matrix and show how to manipulate the zero-transmission mode in a nonunitary system. In a photonic topological insulator, we realize an edge mode and discuss its robustness in the face of ...


Linear And Non-Linear Elastic Constants Of Crystalline Materials From First-Principles Calculations, David Cuffari 2020 The Graduate Center, City University of New York

Linear And Non-Linear Elastic Constants Of Crystalline Materials From First-Principles Calculations, David Cuffari

Dissertations, Theses, and Capstone Projects

Novel methods based on the use of density functional theory (DFT) calculations are developed and applied to calculate linear and non-linear elastic constants of materials at zero and finite temperature. These methods rely on finite difference techniques and are designed to be general, numerically accurate, and suitable to investigate the thermoelastic properties of anharmonic materials. A first method was developed to compute the third-order elastic constants of crystalline materials at zero temperature, a task that is numerically challenging and is currently undertaken by using approaches typically applicable to cubic and hexagonal crystalline systems. This method relies on numerical differentiation of ...


Control Of Molecular Energetics And Transport Via Strong Light-Matter Interaction, Rong Wu 2020 The Graduate Center, City University of New York

Control Of Molecular Energetics And Transport Via Strong Light-Matter Interaction, Rong Wu

Dissertations, Theses, and Capstone Projects

Strong light-matter coupling in excitonic systems results in the formation of half-light half-matter quasiparticles called exciton polaritons. These hybrid quasiparticles take on the best of both systems, namely, the long-range propagation and coherence arising from the photonic component and the nonlinear interaction from the excitonic component. We develop methods for making high quality factor cavities and investigate the potential applications of these strongly coupled states arising specifically in organic molecular systems.

In the first project we investigate the potential of organic dye molecules to undergo condensation in an optical cavity at room temperature. The second study involves the use of ...


Experimental Determination Of The Critical Spin-Glass Correlation Length In Single-Crystal Cumn, G. G. Kenning, Deborah L. Schlagel, V. Thompson 2020 Indiana University of Pennsylvania

Experimental Determination Of The Critical Spin-Glass Correlation Length In Single-Crystal Cumn, G. G. Kenning, Deborah L. Schlagel, V. Thompson

Ames Laboratory Accepted Manuscripts

Using high resolution superconducting quantum interference device magnetometry we have made detailed measurements of the waiting time effect of the thermoremanent magnetization (TRM) decays on a single-crystal CuMn(6%) spin-glass sample near T-g. We have systematically mapped the rapid decrease of the characteristic timescale tw(eff), approaching T-g from below, for waiting times ranging from 100 to 100 000 s. Using tw(eff) to determine the length scale of the growth of correlations during the waiting time, xi(TRm) (observed in both numerical studies and experiment), we observe both growth of xi(TRm) in the spin-glass phase and then a ...


Yield-Stress Fluids In Confined Geometries, Thalia Magyar 2020 The University of Western Ontario

Yield-Stress Fluids In Confined Geometries, Thalia Magyar

Electronic Thesis and Dissertation Repository

A yield-stress fluid is a material that has properties of both solids and conventional liquids that only begins to flow when subject to a finite stress. The behaviour of yield-stress fluids is interesting and important in many applications. It is expected that the rheological properties of a yield-stress fluid will change when confined to a region with a length scale comparable to the characteristic scale of its microstructure. The particle size and polydispersity of two yield-stress fluids, Carbopol and poly(N-isopropylacrylamide), were determined using dynamic light scattering. A rheological characterization was performed on these two yield-stress fluids. Flow of ...


Lightwave Terahertz Quantum Manipulation Of Nonequilibrium Superconductor Phases And Their Collective Modes, M. Mootz, Jigang Wang, I. E. Perakis 2020 University of Alabama at Birmingham

Lightwave Terahertz Quantum Manipulation Of Nonequilibrium Superconductor Phases And Their Collective Modes, M. Mootz, Jigang Wang, I. E. Perakis

Ames Laboratory Accepted Manuscripts

We present a gauge-invariant density matrix description of nonequilibrium superconductor (SC) states with spatial and temporal correlations driven by intense terahertz (THz) lightwaves. We derive superconductor Bloch-Maxwell equations of motion that extend Anderson pseudospin models to include the Cooper pair center-of-mass motion and electromagnetic propagation effects. We thus describe quantum control of dynamical phases, collective modes, quasiparticle coherence, and high nonlinearities during cycles of carrier wave oscillations, which relates to our recent experiments. Coherent photogeneration of a nonlinear supercurrent with a dc component, achieved via condensate acceleration by an effective lightwave field, dynamically breaks the equilibrium inversion symmetry. Experimental signatures ...


Understanding The Magnetic Properties Of Ii-Vi Semiconductor Nanocrystals, Alex Khammang 2020 University of Maine

Understanding The Magnetic Properties Of Ii-Vi Semiconductor Nanocrystals, Alex Khammang

Electronic Theses and Dissertations

Semiconductor nanocrystals (NC) are well known for their unique size tunable optical properties making them suitable candidates for devices such as light emitting diodes (LEDs), solar cells, and cellular labels. II-VI semiconductors in the bulk form behave diamagnetically, but can inherit paramagnetic (PM) or ferromagnetic (FM) properties at the nanoscale. Reports suggest that the emergence of weak PM or FM behavior in undoped NCs are attributed to the increased surface to volume ratio compared for NCs. Traditionally, these NCs only obtain magnetic properties after doping with certain transition metals, such as Co, Mn, or Fe. Many mechanisms have been proposed ...


Vortex Cores In Narrow Thin-Film Strips, Vladimir G. Kogan, Masanori Ichioka 2020 Iowa State University and Ames Laboratory

Vortex Cores In Narrow Thin-Film Strips, Vladimir G. Kogan, Masanori Ichioka

Ames Laboratory Accepted Manuscripts

We study vortex current distributions in narrow thin-film superconducting strips with the help of analytic expression of the vortex current derived within the London theory. Using definition of the vortex core “boundary” as a curve where the current reaches the depairing value, vortex core size and shape are estimated as a function of vortex position in the strip. We show that the core size near the strip edges is smaller than in the rest of the strip, indicating that the Bardeen–Stephen flux-flow resistivity should be reduced near the edges. Moreover, at elevated temperatures, when the depairing current is small ...


Fifth-Degree Elastic Energy For Predictive Continuum Stress–Strain Relations And Elastic Instabilities Under Large Strain And Complex Loading In Silicon, Hao Chen, Nikolai A. Zarkevich, Valery I. Levitas, Duane D. Johnson, Xiancheng Zhang 2020 East China University of Science and Technology

Fifth-Degree Elastic Energy For Predictive Continuum Stress–Strain Relations And Elastic Instabilities Under Large Strain And Complex Loading In Silicon, Hao Chen, Nikolai A. Zarkevich, Valery I. Levitas, Duane D. Johnson, Xiancheng Zhang

Aerospace Engineering Publications

Materials under complex loading develop large strains and often phase transformation via an elastic instability, as observed in both simple and complex systems. Here, we represent a material (exemplified for Si I) under large Lagrangian strains within a continuum description by a 5th-order elastic energy found by minimizing error relative to density functional theory (DFT) results. The Cauchy stress—Lagrangian strain curves for arbitrary complex loadings are in excellent correspondence with DFT results, including the elastic instability driving the Si I → II phase transformation (PT) and the shear instabilities. PT conditions for Si I → II under action of cubic axial ...


An Expanded Model Of Unmatter From Neutrosophic Logic Perspective: Towards Matter-Spirit Unity View, Florentin Smarandache, Victor Christianto, Robert Neil Boyd 2020 University of New Mexico

An Expanded Model Of Unmatter From Neutrosophic Logic Perspective: Towards Matter-Spirit Unity View, Florentin Smarandache, Victor Christianto, Robert Neil Boyd

Mathematics and Statistics Faculty and Staff Publications

In Neutrosophic Logic, a basic assertion is that there are variations of about everything that we can measure; the variations surround three parameters called T, I, F (truth, indeterminacy, falsehood) which can take a range of values. A previous paper in IJNS, 2020 shortly reviews the links among aether and matter creation from the perspective of Neutrosophic Logic. In any case, matter creation process in nature stays a major puzzle for physicists, scientists and other science analysts. To this issue neutrosophic logic offers an answer: "unmatter." This paper examines an extended model of unmatter, to incorporate issue soul solidarity. So ...


Electron Emission And Transport Properties Database For Spacecraft Charging Models, Phil Lundgreen 2020 Utah State University

Electron Emission And Transport Properties Database For Spacecraft Charging Models, Phil Lundgreen

Theses and Dissertations

Modeling the rate and likelihood of spacecraft charging during spacecraft mission is critical to determine mission length, proposed spacec­raft attitude, and spacecraft design. The focus of this work is the creation and utilization of a database of secondary electron yield (SEY) measurements for a host of materials to increase accuracy in spacecraft modeling. Traditional methods of SEY data selection for input into spacecraft charging codes typically include the use of compiled materials databases incorporated in charging codes or selecting values from a specific scientific study. The SEY database allows users to select data inputs based upon the details associated ...


Free Charge Carrier Properties In Two-Dimensional Materials And Monoclinic Oxides Studied By Optical Hall Effect, Sean Knight 2020 University of Nebraska - Lincoln

Free Charge Carrier Properties In Two-Dimensional Materials And Monoclinic Oxides Studied By Optical Hall Effect, Sean Knight

Theses, Dissertations, and Student Research from Electrical & Computer Engineering

In this dissertation, optical Hall effect (OHE) measurements are used to determine the free charge carrier properties of important two-dimensional materials and monoclinic oxides. Two-dimensional material systems have proven useful in high-frequency electronic devices due to their unique properties, such as high mobility, which arise from their two-dimensional nature. Monoclinic oxides exhibit many desirable characteristics, for example low-crystal symmetry which could lead to anisotropic carrier properties. Here, single-crystal monoclinic gallium oxide, an AlInN/GaN-based high-electron-mobility transistor (HEMT) structure, and epitaxial graphene are studied as examples. To characterize these material systems, the OHE measurement technique is employed. The OHE is a ...


High Pressure Synchrotron Xrd, Nfs, And Nrixs Studies Of Fesb2, Melanie Alden White 2020 University of Nevada, Las Vegas

High Pressure Synchrotron Xrd, Nfs, And Nrixs Studies Of Fesb2, Melanie Alden White

UNLV Theses, Dissertations, Professional Papers, and Capstones

This work combines high pressure synchrotron X-ray diffraction (XRD), nuclear forward scattering (NFS), and nuclear resonant inelastic X-ray scattering (NRIXS) experiments on iron diantimonide (FeSb2), a promising thermoelectric material. NRIXS uses the interaction between excited nuclear and lattice states to directly measure the phonon density of states (PDOS) for samples containing certain Mössbauer isotopes. For our experiments, we synthesized FeSb2 enriched with the isotope 57Fe and measured the partial PDOS for 57Fe sites in the FeSb2 lattice. NFS, also known as synchrotron Mössbauer spectroscopy, is a sister technique to NRIXS that studies the hyperfine structure of the excited Mössbauer nuclei ...


Heterostructure Of 2d Materials: Hfs2/Hfo2/Si, Christopher J. Robledo 2020 Missouri State University

Heterostructure Of 2d Materials: Hfs2/Hfo2/Si, Christopher J. Robledo

MSU Graduate Theses

Heterostructures have been utilized in electronic devices for over 50 years with the proposal for the first heterostructure transistor in 1957. With the scaling of devices, it is necessary to create new heterostructures that will comply with Moore’s Law, as well as make devices faster and consume less power. Novel 2D materials, such as hafnium disulfide, have shown promise as an active channel layer, while hafnium dioxide is already proven to be a replacement of silicon dioxide for the gate insulating layer. However, fabrication techniques for wide-scale integration of these heterostructures have not yet been achieved. Also, the dielectric ...


Ferrimagnetism In Eufe4as12 Revealed By Eu-153 Nmr And As-75 Nqr Measurements, Qingping Ding, H.-C. Lee, K. Nishine, Y. Kawamura, C. Sekine, Yuji Furukawa 2020 Iowa State University and Ames Laboratory

Ferrimagnetism In Eufe4as12 Revealed By Eu-153 Nmr And As-75 Nqr Measurements, Qingping Ding, H.-C. Lee, K. Nishine, Y. Kawamura, C. Sekine, Yuji Furukawa

Ames Laboratory Accepted Manuscripts

Filled skutterudite compound EuFe4As12 shows the highest magnetic ordering temperature of TC=154K among Eu-based skutterudite compounds, but its magnetic ground state has not been determined yet. Here, we performed 153Eu nuclear magnetic resonance (NMR) and 75As nuclear quadrupole resonance (NQR) measurements on EuFe4As12 to reveal its magnetic ground state as well as the physical properties from a microscopic point of view. From the temperature and magnetic field dependence of 153Eu NMR spectrum in the magnetically ordered state, we found that the Eu ions are in Eu2+ state with a nearly 7 μB corresponding to S=7/2 spins. Combined ...


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