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This dissertation focuses on the transport properties of the high-temperature superconductor LSCO in high magnetic fields, particularly the longitudinal magnetoresistance around optimum doping. In this region of the phase diagram the...
We studied the relationship between superconductivity and magnetism in the heavy fermion CeCoIn5 using a miniature cell in a top loading dilution refrigerator with a 16 T magnet (XCF – Xtreme Conditions Fridge). The construction and...
In this thesis we have combined the idea of cluster expansion and path integration to develop the quantum version of cluster and virial expansion. We derive a diagrammatic series expansion for different thermodynamic quantities like free...
This thesis studied the electronic structure at the Fermi level and the topological character of topological semimetals via torque magnetometry. Torque magnetometry measures the anisotropic magnetization of the sample in a tilted...
This dissertation is a theoretical and computational examination of structural, electronic and magnetic properties of complex transition metal oxide structures. Our work is motivated by experimental observations that transition metal...
Materials that contain f-electron elements often exhibit complex phase diagrams with different phenomena including nematic electronic states, charge and spin instabilities, the breakdown of Fermi liquid behavior, and unconventional...
This dissertation is focused on electrical spin injection and detection at the nanoscale dimensions that semiconductor nanowires offer. Semiconductor spintronics is the natural extension of metallic spintronics for applications in...
The discovery of graphene marked a turning point in research and interest towards 2 -D materials. Among them, Transition Metal Dichalcogenides (TMDs) and Metal Monochalcogenides (MM) have seen an upturn in interest owing to their...
Geometrically frustrated systems have garnered much interest in recent times due to the emergence of novel magnetic states in these systems that contrast traditional cooperative magnetic phenomena. The spin ice pyrochlores Ho2Ti2O7 and...
Transition metal dichalcogenides (TMDs or TMDCs) have garnered much interest recently due to their weakly layered structures, allowing for mechanical exfoliation down to a single atomic layer. As such, it is pertinent to re-examine the...
Two heavy Fermion superconducting compounds, URu₂Si₂ and PuRhIn₅, were investigated by the techniques of chemical substitution and application of high magnetic fields. These materials are particularity interesting for their unique...
We report a study on the magnetotransport properties and on the Fermi surfaces (FS) of the ZrSi(Se, Te) semimetals. Density Functional Theory (DFT) calculations, in absence of spin orbit coupling (SOC), reveal that both the Se and the Te...
Understanding properties of quasiparticles in novel two-dimensional (2D) semiconductors, such as atomically thin transition metal dichalcogenides (TMDCs) and group-III metal monochalcogenides, is among the most interesting topics in...
The control of dynamics of spins in solid-state materials has direct implications at both fundamental and applied levels. Research topics, in particular quantum computing, rely heavily on both complex control techniques and long spin...
Recent discoveries of new high temperature superconductors initiated investigations to harness these new materials' properties. Unfortunately, many new high temperature superconductors come with odd properties such as multi-band...
Superfluid 4He (He II) has been widely used as a coolant material in many engineering applications. Its unique heat transfer mode is the so-called thermal counterflow. The study of thermal counterflow will contribute to the design of He...
Quantum computing gives novel way of computing using quantum mechanics, which furthers human knowledge and has exciting applications. Quantum systems with diluted spins such as rare earth ions hosted in single crystal, molecule-based...
This dissertation examines the theoretical and computational methods needed to calcu- late opto-electronic multiple-carrier excitation rates in strongly correlated insulators (SCI). Through several studies, we find that we are able to...
Semiconductor spintronics is widely regarded as a viable pathway to overcome many of the physical limitations of the present micro-electronics technology. Electrical spin injection into a semiconductor, coherent transport and...
Semiconductor nanostructures have shown great potential for detecting and measuring chemical and biological interactions. The advantage of the electrically based schemes is real-time, label-free detection, which had been absent from...
Computational material simulation is becoming more and more important as a branch of material science. Depending on the scale of the systems, there are many simulation methods, i.e. first-principles calculation (or ab-initio), molecular...
Electrophoresis as an analytical technique has made considerable contributions to the separations and analysis of macromolecules in biology-related research. Pluronic gels, which are composed of orderly packed spherical micelles...
At low temperature (T) and weak magnetic field (B), two dimensional electron systems (2DES) can exhibit strong 1/B-periodic resistance oscillations on application of sufficiently strong microwave radiation. These oscillations are known...
Strongly correlated materials are a class of materials that cannot be properly described by the Density Functional Theory (DFT), which is a single-particle approximation to the original many-body electronic Hamiltonian. These systems...
Quantum computers are predicted to outperform classical computers in certain tasks, such as factoring large numbers and searching databases. The construction of a computer whose operation is based on the principles of quantum mechanics...
Understanding new quantum phenomena and properties of new materials is the foundation of condensed matter physics. One can mention celebrated examples of integer and fractional quantum Hall effect, Aharonov-Bohm quantum interference...
As the discovery of quantum mechanics signified a revolution in the world of physics more than one century ago, the notion of a quantum computer in 1981 marked the beginning of a drastic change of our understanding of information and...
We introduce a new nonlinear equation, the Self-Dual Nonlinear Schrödinger Equation (SDNLS) which resembles the Gross-Pitaevskii Equation [6] [4]. Unique to the SDNLS is its invariance under the Fourier transform — a form of duality...
Organic conductors are interesting to study due to their low dimensionality that leads to a number of competing low temperature ground states. Comprised of a number of different molecules that can be varied by the substitution of one...
Transition metal oxides and chalcogenides have been the major focus of studies in condensed matter physics. The complexity of the system, involving spin and orbital effects, as well as lattice degree of freedom, makes them intriguing...
In this dissertation, we investigate the edge spin excitations and reconstructions of quantum Hall (QH) liquids. Edge spin reconstructions reflect the interplay of confining potential, electron-electron interaction, and Zeeman splitting...
Nanoscience and nanotechnology research has provided us with new paradigms of technologies to improve human life, but still there is plenty of room to expand its frontiers. In order to do so, we need to pursue the development and study...
This dissertation presents studies on mononuclear single molecule magnets (SMMs) with magnetic properties arising from transition metal ions in trigonal bipyramidal (TBP) coordination environments. We use both experimental and...
The purpose of this thesis is to present the results of how the preparation of a sample of Uranium-238 changes its crystal quality. First this thesis will explain the process of etching Uranium and what this does to a crystal batch. This...
Crystalline materials that include 4f- and 5f-electron elements frequently exhibit a variety of intriguing phenomena including spin and charge orderings, spin and valence fluctuations, heavy fermion behavior, breakdown of Fermi liquid...
The Weyl semimetal requires the breaking of either the time-reversal symmetry (TRS) or the lattice inversion symmetry. When the TRS and inversion symmetry coexist, a pair of degenerate Weyl points may exist, leading to the related Dirac...
Computational Studies of Equilibrium and Non-Equilibrium Phase Diagrams and Critical Properties of Two Physical and Chemical Model Systems with Both Short-Range and Long-Range Interactions or Reactivities
In this dissertation, we introduce long-range interactions into one equilibrium model (Ising model) and one non-equilibrium system (Ziff-Gulari-Barshad model), and study their phase diagrams and critical properties. A new approach to do...
Complex physical phenomena, such as superconductivity, colossal magnetoresistance (CMR) effect, multi-ferroics, metal-insulator transition, quantum phase transition, etc. in strongly correlated materials have been enduring topics in...
We have measured the electrical resistivity and magnetoresistance of several α-uranium single crystals under pressure. The residual resistivity ratios (RRRs) of these samples ranged from 158 to 265 and the pressure dependence is...
We report the synthesis and characterization for two single crystalline lanthenide-host compound Sm$_{6}$T$_{4}$Al$_{43}$ (T = Mo and W), that form in the hexagonal Ho$_{6}$Mo$_{4}$Al$_{43}$ prototype. The Sm ions reside within T/Al...
This dissertation details the use of 93Nb (γ = 10.405 MHz/T, I = 9/2) and 77Se (γ = 8.13 MHz/T, I = 1/2) nuclear magnetic resonance (NMR) to investigate the phase transitions of the layered transition metal dichalcogenide (TMD) niobium...
The understanding of magnetic materials has become crucial to both fundamental physics and technological advancement. Particularly, the interplay between magnetic and electronic properties has given rise to such novel physics as high...
This dissertation is a theoretical and computational examination of electronic properties of topological materials, such as topological insulators and Weyl semimetals. Our work is motivated by various experimental observations and...
The Bardeen-Cooper-Schrieffer (BCS) theory of superconductivity is one of the jewels of 20th century physics. In this theory, the superconducting state of a metal is understood in terms of the formation of electron pairs which condense...
The dissertation presents the recent development of the 3rd generation femtosecond electron diffractometer in Professor Jim Cao's group. Two techniques, femtosecond electron shadow imaging and deflectometry (FESID) and femtosecond...
The understanding of the electronic systems of materials has not been only the essential, but the driving force, behind the progress of technology for over 100 years. This year marks the 60th anniversary of the revolutionary Bardeen...
This dissertation presents the recent developments and experiments performed using the third generation femtosecond electron diffractometer in Professor Jianming Cao's group as well as experiments performed using the previous second...
Topological phases of matter and the phase transitions between them have been the focus of much recent theoretical and experimental interest. In this thesis, we firstly study a type of topological phase transitions between quantum Hall...
High temperature superconductors (HTS) allow for the construction of magnets generating fields of more than 30 T, enabling the investigation of new phenomena in condensed matter science and high energy physics. High field magnets store...
Since the simplest case was solved exactly by Onsager in 1944, the two-dimensional Ising model has become one of the most studied models in statistical physics. Despite its simplicity, it has found applications in research ranging from...
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