Condensed Matter Physics Commons^™

Physical And Magnetic Properties Of Nanosized Mn0.5ni0.5¬Fe2-Xprxo4 Prepared By Co-Precipitation Method, Douaa El-Said Bakeer, Khulud Habanjar, Ghassan Youness, Mohammad Abou Ghoush

BAU Journal - Science and Technology

Nanosized Mn_0.5Ni_0.5Fe_2-xPr_xO₄, x=0.0, 0.02, 0.04, 0.06, 0.08, 0.1 and 0.15 are prepared by co-precipitation method at calcination temperature 650^oC for 4 hours. X-ray diffraction patterns show the presence of the cubic (Mn-Ni)- ferrite phase and anti-ferromagnetic a-Fe₂O₃. The variation in the lattice parameter “a” is due to the replacement of smaller radius ions Fe⁺³ by larger radius ions Pr⁺³. Transmission electron micrographs indicate that the particles are spherical in shape. The moderately agglomerated particles are present due to the …

Discovery Of An Olivine-Type Lithium Manganese Thiophosphate, Limnps4,: Via A Building Block Approach, Srikanth Balijapelly, Kartik Ghosh, Aleksandr V. Chernatynskiy, Amitava Choudhury

Physics Faculty Research & Creative Works

An olivine-type orthothiophospate LiMnPS4 has been synthesized for the first time through a building block approach by reacting preformed ternary lithium thiophospate with MnCl2. Diffuse reflectance measurements show an optical band gap of 2.36 eV, which is further confirmed by DFT calculations. Irreversible weak ferromagnetic ordering and metamagnetism are verified through preliminary magnetic measurements.

Spin-Dependent Electronic Transport In Noncollinear Antiferromagnetic Antiperovskites, Gautam Gurung

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

Spin-dependent properties are the heart of spintronic devices. Spintronics exploits electron’s spin, in addition to charge, to process and store the information. Recently, antiferromagnetic (AFM) spintronics has emerged as a subfield of spintronics, where an AFM order parameter (the Néel vector) is exploited to control spin-dependent transport properties. Due to being robust against magnetic perturbations, producing no stray fields, and exhibiting ultrafast dynamics, antiferromagnets can serve as promising functional materials for spintronic applications.

Among antiferromagnets, high Néel temperature noncollinear antiperovskites ANMn₃ (A = Ga, Ni, Sn, and Pt) are interesting due to their magnetic group symmetry supporting non-trivial spin-dependent …

Study Of The Geometric Structure Of Low-Atomic Copper Clusters Using Computer Simulation, Nodirbek Ikromjonovich Ibrokhimov

Scientific-technical journal

In this work, we investigated the geometric structure of small neutral copper clusters with low energy using the MD (Molecular Dynamics) method. When calculating the processes of interatomic interaction, we used a potential EAM (Embedded-atom method). A computer model of Cu_n (n = 2-13) clusters has been created. The geometric shapes of the Cu₂, Cu₃, Cu₄, Cu₅, Cu₆, Cu₇, Cu₈, Cu₉, Cu₁₀, Cu₁₁, Cu₁₂, and Cu₁₃ clusters have been studied and the structural parameters (Cu-Cu bond …

Signatures Of A Quantum Griffiths Phase Close To An Electronic Nematic Quantum Phase Transition, Pascal Reiss, David Graf, Amir A. Haghighirad, Thomas Vojta, Amalia I. Coldea

Physics Faculty Research & Creative Works

In the vicinity of a quantum critical point, quenched disorder can lead to a quantum Griffiths phase, accompanied by an exotic power-law scaling with a continuously varying dynamical exponent that diverges in the zero-temperature limit. Here, we investigate a nematic quantum critical point in the iron-based superconductor FeSe0.89S0.11 using applied hydrostatic pressure. We report an unusual crossing of the magneto resistivity isotherms in the Non superconducting normal state that features a continuously varying dynamical exponent over a large temperature range. We interpret our results in terms of a quantum Griffiths phase caused by nematic islands that result from the local …

Preparation And Characterization Of Multiwall Carbon Nanotubes Decorated With Copper Oxide, Mohamed Morsy

Nanotechnology Research Centre

Multi-walled carbon nanotubes (MWCNTs) are special form of carbon nano materials with amazing applications in many areas of research.MWCNTs were synthesized by anAtmospheric Chemical Vapor Deposition (ACVD) system then decorated on their surface with Copper Oxide (CuO) nanoparticles via the hydrothermal method. The prepared un-purifiedMWCNTs and purified MWCNTs were characterized by High Resolution Transmittance Electron Microscope (HRTEM), Xray Diffraction (XRD) and Raman spectroscopy. As well as the CuO/MWCNTs nanocomposite was characterized by HRTEM, XRD, Fourier Transform Infra-Red Spectroscopy (FTIR), Thermogravimetric Analysis (TGA) Differential Thermal Analysis (DTA) and Raman spectroscopy. The results demonstrated the distribution of CuO nano particles on the …

Rigid Aggregation Of Inclusions Embedded In Quasi 2d Fluids, Natalie Xochitl Ryan

Physics

Diffusion is a transport process common in several biological systems. In this process particles of different species mix together through random (stochastic) motion at molecular length scales. Diffusion in fluids is unique as the coupling of the flow and fluid have been found to produce giant concentration fluctuations. The molecular length scale of these concentration fluctuations are magnitudes larger than the movement of the particles themselves, earning them the title “giant”. The diffusion of particles in bio-membranes displays a combination of 2D and 3D hydrodynamic properties; the movements of the particles are restricted to the plane of the membrane and …

Ultrafast Magnetic Entropy Dynamics With Time-Resolved Pump-Probe Magneto-Optical Technique., Sahar Goharshenasanesfahani

Electronic Theses and Dissertations

It has been observed that ultrathin films, multilayers, or magnetic nanostructures indicate novel magnetic phenomena that differ profoundly from the respective bulk properties. Besides, because of the broad applications of these magnetic materials in the industry, they are an exciting research area. Hence, investigating the low-dimensional magnetic systems is one of the most active fields in experimental condensed matter physics. Magnetization dynamics can occur over a wide range of time scales (from seconds to femtoseconds). Some of these processes even occur on time scales as short as a few picoseconds (10^-12s) or femtoseconds (10^-15s). Measurement of …

Towards Long Term Colloid Suspension In A Vertically Rotated System., Md Mahmudur Rahman

Electronic Theses and Dissertations

Within a colloidal suspension gravity may compromise the observation of governing physical interactions, especially those that are weak and/or take significant time to develop. Conducting the experiment in a long-term microgravity environment is a viable option to negate gravitational effects, though significant resources are required to do so. While it may not be possible to simulate long-term microgravity terrestrially, particles can resist quick sedimentation in a confined suspension system rotating vertically with appropriate rotation speed. The goal of the investigation is to demonstrate the existence of long-term particle suspension regime for a certain colloidal suspension while characterizing colloidal behavior due …

First Principle Studies Of The Effects Of Alkali-Metal Intercalation On Structural Transition From Black To Blue Phosphorene And The Adsorption Of N2h4 On Ws2 Layers., Md Rajib Khan Musa

Electronic Theses and Dissertations

A comprehensive density functional theory calculation has been conducted to seek a potential structural transition from black to blue phosphorene layers, with a focus on the roles played by alkali-metal intercalation in black phosphorene/phosphorus. This study reveals that at sufficiently high Li concentration and specific, well-defined configurations, a phase transition from black to blue phosphorene can take place. The Li atoms intercalated in black phosphorene could act as a “catalyst” in the“reactive region” of the lone pair of P atoms, leading to a P-P bond breaking and, subsequently, a local structural transformation from an orthorhombic lattice to an assembly of …

Entropic Density Functional Theory : Entropic Inference And The Equilibrium State Of Inhomogeneous Fluids, Ahmad Yousefi

Legacy Theses & Dissertations (2009 - 2024)

A unified formulation of the density functional theory is constructed on the foundations of entropic inference in both the classical and the quantum regimes. The theory is introduced as an application of entropic inference for inhomogeneous fluids in thermal equilibrium. It is shown that entropic inference reproduces the variational principle of DFT when informationabout expected density of particles is imposed. In the classical regime, this process introduces a family of trial density-parametrized probability distributions, and consequently a trial entropy, from which the preferred one is found using the method of Maximum Entropy (MaxEnt). In the quantum regime, similarly, the process …

Dreams Of Molecular Beams: Indium Gallium Arsenide Tensile-Strained Quantum Dots And Advances Towards Dynamic Quantum Dots (Moleculare Radiorum Somnia: Indii Gallii Arsenicus Tensa Quanta Puncta Et Ad Dinamicae Quantae Puntae Progressus), Kevin Daniel Vallejo

Boise State University Theses and Dissertations

Through the operation of a molecular beam epitaxy (MBE) machine, I worked on developing the homoepitaxy of high quality InAs with a (111)A crystallographic orientation. By tuning substrate temperature, we obtained a transition from a 2D island growth mode to step- ow growth. Optimized MBE parameters (substrate temperature = 500 °C, growth rate = 0.12 ML/s and V/III ratio ⩾ 40) lead to growth of extremely smooth InAs(111)A films, free from hillocks and other 3D surface imperfections. We see a correlation between InAs surface smoothness and optical quality, as measured by photoluminescence spectroscopy. This work establishes InAs(111)A as a platform …

Computational Study Of Grain Structure Evolution In Cdte/Cds Via Molecular Dynamics, Sharmin Abdullah

Open Access Theses & Dissertations

Grain structure analysis plays an important role in the identification of grain boundary characteristics, which can affect the efficiency of Cadmium Telluride/Cadmium Sulfide (CdTe/CdS) solar cells since they can act as recombination centers for carriers. Computer simulations such as molecular dynamics (MD) can be a very convenient and cost- effective method of investigating the growth evolution and grain structure of materials. The recently reported and experimentally validated MD simulated growth of polycrystalline CdTe/CdS films shows that these materials mostly consist of zinc blende (ZB) and wurtzite (WZ) structures, along with highly disordered atoms. However, little information about the semiconductor compound …

Ab-Initio And Empirical Simulations Of Aluminum And Copper Metal, William Wolfs

UNLV Theses, Dissertations, Professional Papers, and Capstones

In this work, I perform detailed calculations on the bulk and electronic properties of aluminum and copper metal. Originally, I was motivated by experimental work on the solidsolid phase changes in pure aluminum. These phase changes were well predicted by density functional theory(DFT) but difficult or impossible to predict using embedded atom method potentials(EAM). EAM potentials are in wide use to describe many properties of bulk materials, and it seemed worrying that something so basic as a phase change could not be predicted. I began running high precision calculations with DFT and compared the results to EAM potentials which had …

Voltage Controlled Néel Vector Rotation In Zero Magnetic Field, Ather Mahmood, Will Echtenkamp, Mike Street, Jun Lei Wang, Shi Cao, Takashi Komesu, Peter Dowben, Pratyush Buragohain, Haidong Lu, Alexei Gruverman, Arun Parthasarathy, Shaloo Rakheja, Christian Binek

Peter Dowben Publications

Multi-functional thin films of boron (B) doped Cr₂O₃ exhibit voltage-controlled and nonvolatile Néel vector reorientation in the absence of an applied magnetic field, H. Toggling of antiferromagnetic states is demonstrated in prototype device structures at CMOS compatible temperatures between 300 and 400 K. The boundary magnetization associated with the Néel vector orientation serves as state variable which is read via magnetoresistive detection in a Pt Hall bar adjacent to the B:Cr₂O₃ film. Switching of the Hall voltage between zero and non-zero values implies Néel vector rotation by 90 degrees. Combined magnetometry, spin resolved inverse …

Theoretical Investigations Of The Structural, Dynamical, Electronic, Magnetic, And Thermoelectric Properties Of Corhysi (Y = Cr, Mn) Quaternary Heusler Alloys, Abdullah Hussain Hzzazi

Graduate Theses and Dissertations

Thermoelectric materials have potential properties for utilizing waste heat. The computations are used to estimate the electronic structure of CoRhYSi (Y = Cr, Mn) Quaternary Heusler alloys, as well as their elastic and magnetic characteristics. The full-potential linearized augmented plane wave is used in the calculations. The exchange-correlations are addressed using Perdew–Burke and Ernzerhof's generalized gradient approximation (GGA-PBE). With the exception of CoRhCrSi and CoRhMnSi, which are simple ferromagnets that are approximately half metallic in nature, electronic structure calculations demonstrate that these compounds have a gap in the minority states band and are obviously half-metallic ferromagnets. The magnetic moments of …

Interplay Between The Lattice And Spin Degrees Of Freedom In Magnetoelectric And Magnetic Materials, Temuujin Bayaraa

Graduate Theses and Dissertations

This dissertation contains several investigations on the cross-coupling between structural and spin degrees of freedom in multiferroic and ferrimagnetic compounds by means of first-principles calculations and ab-initio-based Monte-Carlo simulations. We start with the reviews of magnetoelectricity, ferrimagnetism, strain engineering, followed by a brief introduction to first-principles computational methods, magnetic effective Hamiltonians, and other techniques that are utilized here. The results section of the dissertation can be divided into two parts. The first half focuses on magnetoelectric effects arising from different sources, while the second half is about the ferrimagnetic nature of materials. In the first part, we examine the epitaxial …

Gaas Growth On Sapphire Substrates (C And R Plane) For Integrated Microwave Photonics (Imwp), Samir Kumar Saha

Graduate Theses and Dissertations

The microwave signal processing in the optical domain creates new opportunities for information and communication technology (ICT) and networks by increasing speed, bandwidth, and processing capability. IMWP incorporates the functions of microwave photonics components/subsystems in monolithic or hybrid photonic circuits to meet future needs. Sapphire platforms have the potential to integrate all-in-one, for instance, light source, analog signal processing, light detection, CMOS control circuit, silicon on sapphire to achieve high-performance, low-cost mixed-signal optical links etc. Molecular beam epitaxy (MBE) has been used to grow GaAs on sapphire substrates to integrate optoelectronic devices in the same platform.

The initial stage of …

Two-Dimensional Black Phosphorus For Terahertz Emission And Near-Field Radiative Heat Transfer, Mahmudul Hasan Doha

Graduate Theses and Dissertations

The main focus of this work is to investigate two potential optical and optoelectronic applications of black phosphorus (BP): the near-field radiative heat transfer in plasmonic heterostructures with graphene and terahertz emission from multi-layer BP photoconductive antennas. When the separation distance between graphene-black phosphorene is much smaller than or comparable to the thermal wavelength at different temperatures, a near-field radiation heat transfer breaks the Planck blackbody limit. The magnitude of the near-field radiation enhancement acutely depends on the gate voltage, doping, and vacuum gap of the graphene and BP pair. The strong near-field radiation heat transfer enhancement of the specific …

Effect Of Pressure On The Electrical Transport And Structural Properties Of Ybnio3, Mostafa Gala El Dine Zeama

Archived Theses and Dissertations

No abstract provided.