Condensed Matter Physics Commons^™

Majorana Bound States With Chiral Magnetic Textures, Utkan Güngördü, Alexey Kovalev

Alexey Kovalev Papers

The aim of this Tutorial is to give a pedagogical introduction into realizations of Majorana fermions, usually termed as Majorana bound states (MBSs), in condensed matter systems with magnetic textures. We begin by considering the Kitaev chain model of “spinless” fermions and show how two “half” fermions can appear at chain ends due to interactions. By considering this model and its two-dimensional generalization, we emphasize intricate relation between topological superconductivity and possible realizations of MBS. We further discuss how “spinless” fermions can be realized in more physical systems, e.g., by employing the spin-momentum locking. Next, we demonstrate how magnetic textures …

Experimental Investigation Of The Physical Properties Of Irmsnn (M = 1, 3 And N = 2, 4, 7), Smita Speer

LSU Doctoral Dissertations

Exploration of transition metal stannides, formed from a combination of transition metals (T) and Sn, has resulted in the discovery a variety of materials with interesting physical properties, which is in part due to the complexity of interactions that can occur between the T-d orbitals and Sn-p orbitals. There have been observations of (extremely) large magnetoresistance [1-4], topological flat and nearly flat bands [5-7], superconducting behavior in 2D and 3D systems [5, 8-11], ultrahigh carrier mobility [12-13], and more attributed to d-p orbital mixing in such systems. This dissertation will address the effects of T-Sn interactions …

Asymmetric Control Of Light At The Nanoscale, Christos Argyropoulos

Department of Electrical and Computer Engineering: Faculty Publications

Breaking reciprocity at the nanoscale can produce directional formation of images due to the asymmetric nonlinear optical response of subwavelength anisotropic resonators. The self-induced passive non-reciprocity has advantages compared to magnet or time modulation approaches and may impact both classical and quantum photonics.

Modeling The Electronic Properties For Cnt Interacted With Zno, Cuo, And Co3o4, Mohamed Morsy

Nanotechnology Research Centre

No abstract provided.

Ultra-High Carrier Mobilities In Ferroelectric Domain Wall Corbino Cones At Room Temperature, Conor J. Mccluskey, Matthew G. Colbear, James P.V. Mcconville, Shane J. Mccartan, Jesi R. Maguire, Michele Conroy, Kalani Moore, Alan Harvey, Felix Trier, Ursel Bangert, Alexei Gruverman, Manuel Bibes, Amit Kumar, Raymong G.P. Mcquaid, J. Marty Gregg

Alexei Gruverman Publications

Recently, electrically conducting heterointerfaces between dissimilar band-insulators (such as lanthanum aluminate and strontium titanate) have attracted considerable research interest. Charge transport has been thoroughly explored and fundamental aspects of conduction firmly established. Perhaps surprisingly, similar insights into conceptually much simpler conducting homointerfaces, such as the domain walls that separate regions of different orientations of electrical polarisation within the same ferroelectric band-insulator, are not nearly so well-developed. Addressing this disparity, we herein report magnetoresistance in approximately conical 180° charged domain walls, which occur in partially switched ferroelectric thin film single crystal lithium niobate. This system is ideal for such measurements: firstly, …

Superfluid Spin Transistor, Edward Schwartz, Bo Li, Alexey Kovalev

Department of Physics and Astronomy: Faculty Publications

We propose to use the Hall response of topological defects, such as merons and antimerons, to spin currents in two-dimensional magnetic insulator with in-plane anisotropy for identification of the Berezinskii-Kosterlitz-Thouless (BKT) transition in a transistorlike geometry. Our numerical results relying on a combination of Monte Carlo and spin dynamics simulations show transition from spin superfluidity to conventional spin transport, accompanied by the universal jump of the spin stiffness and exponential growth of the transverse vorticity current. We propose a superfluid spin transistor in which the spin and vorticity currents are modulated by changes in density of free topological defects, e.g., …

Magnetism Of Novel Rare-Earth-Free Intermetallic Compounds, Haohan Wang

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

Rare-earth-free magnets have drawn lots of interest because of their low cost, and the production is not limited by the shortage of rare-earth elements. This dissertation focuses on three rare-earth-free materials, Fe-Co-Ti alloys, Fe-Ni-B alloys, and Co-Si. All of them are synthesized by arc melting followed by melt-spinning. Fe_3+xCo_3−xTi₂ (x = 0, 2, 3) alloys exhibit hexagonal crystal structures and show non-collinear spin structures according to neutron diffraction. The magnetic moments have projections on both the c-axis and basal plane, and the corresponding misalignment angle exhibits a nonlinear decrease with …

Phase Transitions, Critical Phenomena, And Correlation Functions In The 2d Ising Model And Its Applications To Quantum Dynamics: A Tensor Network Approach, Sankhya Basu

Dissertations, Theses, and Capstone Projects

This thesis explores several aspects of the 2D Ising Model at both real and complex temperatures utilizing tensor network algorithms. We briefly discuss the importance of tensor networks in the context of forming efficient representations of wavefunctions and partition functions for quantum and classical many-body systems respectively, followed by a brief review of the tensor network renormalization algorithms to compute the one point and two point correlation functions. We use the Tensor Renormalization Group (TRG) to study critical phenomena and examine feasibility of accurate estimations of universal critical data for three critical points for three critical points in two dimensions …

Optical Studies Of Wide Bandgap Photonic Materials, Nikesh Maharjan

Dissertations, Theses, and Capstone Projects

In this dissertation work, optical properties of wide bandgap materials such as hexagonal Boron Nitride (h-BN) and Zinc Oxide (ZnO) have been studied. Deep UV photoluminescence spectroscopy was employed to study the optical properties of bulk h-BN and powder crystals using a laser of wavelength 200 nm, which is the fourth harmonic of Ti:Sapphire laser as excitation source. The properties and chemical compositions of annealed and unannealed bulk h-BN were investigated. The PL spectra from h-BN samples annealed at 900 ºC in ambient air, had strong phonon assisted band edge emissions along with a sharp atomic-like emission line at 4.09 …

Investigation Of Topological Phonons In Acoustic Metamaterials, Wenting Cheng

Dissertations

Topological acoustics is a recent and intense area of research. It merges the knowledge of mathematical topology, condensed matter physics, and acoustics. At the same time, it has been pointed out that quasiperiodicity can greatly enhance the periodic table of topological systems. Because quasiperiodic patterns have an intrinsic global degree of freedom, which exists in the topological space called the hull of a pattern, where the shape traced in this topological space is called the phason. The hull augments the physical space, which opens a door to the physics of the integer quantum Hall effect (IQHE) in arbitrary dimensions. In …

Correlations Between The Rotations And Magnetospheres Of The Terrestrial Planets And The Sun's Formation In Our Solar System, Fred J. Cadieu

Publications and Research

Correlations between the rotations of the terrestrial planets in our solar system and the magnetic field of the Sun have been previously noted. These correlations account for the opposite rotation of Venus as a result of the magnetic field of the Sun being dragged across the conducting core of Venus. Currently the Sun’s magnetic field is not sufficiently strong to account for the proposed correlations. But recently meteorite paleomagnetism measurements have indicated that during the Sun’s formation the magnetic field of the Sun was of sufficient strength to have resulted in the observed correlations. As a part of these correlations …

Controlling Magnetic Exchange And Anisotropy By Nonmagnetic Ligand Substitution In Layered M P X 3 ( M = Ni , Mn; X = S , Se), Rabindra Basnet, Kamila M. Kotur, Milosz Rybak, Cory Stephenson, Samuel Bishop, Carmine Autieri, Magdalena Birowska, Jin Hu

Physics Faculty Publications and Presentations

Recent discoveries in two-dimensional magnetism have intensified the investigation of van der Waals magnetic materials and further improved our ability to tune their magnetic properties. Tunable magnetism has been widely studied in antiferromagnetic metal thiophosphates MPX3. Substitution of metal ions M has been adopted as an important technique to engineer the magnetism in MPX3. In this work, we have studied the previously unexplored chalcogen X substitutions in MPX3 (M=Mn/Ni; X=S/Se). We synthesized the single crystals of MnPS3−xSex (0≤x≤3) and NiPS3−xSex (0≤x≤1.3) and investigated the systematic evolution of the magnetism with varying x. Our study reveals the effective tuning of magnetic …

Nonequilibrium And Nonlinear Dynamics In Collective Spin Models And Implementations Using Quantum Feedback Control, Manuel H. Munoz Arias

Physics & Astronomy ETDs

Out-of-equilibrium dynamics generalizes the study of ground states of quantum Hamiltonians at zero temperature, to that of dynamical quasi-steady states of quantum systems far from equilibrium. In this dissertation I discuss dynamical quantum phase transitions and out-of-equilibrium phases of matter in models of collective spins with multi-body interactions. These models, based on collective degrees of freedom, allow an exact description of the thermodynamic limit via the mean-field description. In this limit, the nonequilibrium dynamics of properties of quantum states is mapped to the nonlinear dynamics of classical variables, and thus it can be analyzed using tools from the theory of …

Bio-Based Antibacterial Packaging From Decorated Bagasse Papers With Natural Rosin And Synthesised Go-Ag Nanoparticles, Mohamed Morsy

Nanotechnology Research Centre

No abstract provided.

The Interaction Of Topological Defects In Anisotropically-Elastic Nematic Liquid Crystals, Carter J. Swift

Macalester Journal of Physics and Astronomy

Topological defects are very well understood so long as the medium in which they exist is isotropically-elastic. They lead to director fields which are easy to calculate and superpose linearly so that a system with any number of defects is analytically treatable. They also have an interaction which is simple in form and can be accurately described by the Peach-Koehler force. In an anisotropically-elastic medium, however, such defects are very poorly understood outside of the single-defect case which was solved by Dzyaloshinskii. In this project, numerical and approximate analytical techniques are applied in order to better understand the interaction between …

Finite-Difference-Time-Domain Simulation Of Ultrafast Experiments, Alpha Ma

Macalester Journal of Physics and Astronomy

The Finite-Difference-Time-Domain (FDTD) method is a numerical method that calculates electric fields or magnetic fields by interleaving them in space and time. Using a python package called “MEEP”, I was able to write optical simulations of ultrafast experiments, especially the Terahertz Pump-Probe experiments. The goal of this project was to use FDTD simulation to measure the transmission of an electro-magnetic pulse passing through a thin film of conducting material on a dielectric substrate in order to study the characteristic conductivity of potential solar cell materials.

Approaching Quantum-Limited Electrometry In The Single-Photon Regime, Sisira Kanhirathingal

Dartmouth College Ph.D Dissertations

Mesoscopic quantum systems currently serve as essential building blocks in many quantum information and metrology devices. This thesis investigates the potential of quantum-limited detection in a mesoscopic electrometer named the cavity-embedded Cooper pair transistor (cCPT). As one application, this charge detector can act as the basis for an optomechanical system in the single-photon strong coupling regime. The realization of this scheme would entail near quantum-limited, ultra-sensitive electrometry at the single-photon level, the feasibility of which is studied at length in this thesis.

On the one hand, we approach this question using a fundamental, first-principles study, where an operator scattering model …

Synthesis, Characterization, And Functionality Of Novel 2d Material Sn3p2, Cory Stephenson

Physics Undergraduate Honors Theses

In recent years, two-dimensional (2D) materials have gained a lot of attention due to their potential applications in devices and their promise to revolutionize technology. In our group, we are capable of synthesizing such materials and study their properties. I have discovered a new material of the tin-phosphorus family that displays the 2D layered structure and therefore shows potential to be used in future devices due to this reduced dimensionality from the typical three-dimensional counterpart. This 2D structure may allow for new phenomena to emerge as there is no longer any interatomic interactions along the z- axis. Under this motivation, …

Exploring Tunable Magnetization And High-Temperature Ferromagnetism In Ternary Transition Metal-Based Chalcogenides, Hector Iturriaga

Open Access Theses & Dissertations

The discovery of long-range magnetic ordering in ultrathin transition metal-based compounds shows great promise for the development of nanoscale memory and spintronic devices. Composed of cost-effective materials and boasting from strong chemical and thermal stability at low dimensions, van der Waals (vdW) ternary transition metal chalcogenide magnets like CrSiTe3 (CST), Fe2.7GeTe2 (FGT), and Mn3Si2Te6 (MST), provide not only possible energy solutions, but also a broad platform to explore the versatile magnetic character of this family of compounds. Although they have great potential, it has been found that their long-range magnetic ordering exists at temperatures far too low (the highest of …

Evolution Of The Magnetic Properties On Van Der Waals Layered Magnets Via Pressure And Proton Irradiation, Rubyann Olmos

Open Access Theses & Dissertations

Probing the magnetism in quasi two-dimensional materials has the potential in driving their properties towards future use in spin electronic based devices. Studying such layered magnets will enable the scientific community to uncover tunable exotic phases such as superconductivity, quantum paramagnetism, etc. This work examines the influence of two types of external perturbations, namely, the pressure and proton irradiation, on the magnetic properties of several compounds in the van der Waals crystal family.

Pressure has been found to induce structural and magnetic phase transitions in many of these materials. Using hydrostatic pressure as a disorderless approach to manipulate the interlayer …