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Articles 1 - 10 of 10
Full-Text Articles in Condensed Matter Physics
Developing Dynamical Probes Of Quantum Spin Liquids Inspired By Techniques From Spintronics, Joshua Aftergood
Developing Dynamical Probes Of Quantum Spin Liquids Inspired By Techniques From Spintronics, Joshua Aftergood
Dissertations, Theses, and Capstone Projects
We theoretically study low dimensional insulating spin systems using spin fluctuations as a probe of the spin dynamics. In some systems, low dimensionality in conjunction with other quantum fluctuation enhancing effects impedes spontaneous generation of long range magnetic ordering down to zero absolute temperature. In particular, we focus on exotic spin systems hosting mobile, fractionalized spin excitations above their ground state, and ultimately show that techniques already commonplace in spintronics can be utilized in the context of quantum magnetism to develop probes of exotic ground states.
We initially consider quantum spin chains (QSCs), and examine a system of two exchange-coupled …
Topological Classical Wave Systems With Modulations, Interactions, And Higher-Order Topological States, Mengyao Li
Topological Classical Wave Systems With Modulations, Interactions, And Higher-Order Topological States, Mengyao Li
Dissertations, Theses, and Capstone Projects
Topological phases in classical wave systems, such as photonic and acoustic, have been actively investigated and applied for wave guiding, lasing, and numerous other novel phenomena and device applications Topological phase transitions enable robust boundary states, and the field has been broadening recently into a vast variety of systems with temporal modulations and interactions. Floquet modulation, for example, is the modulation applied periodically in time which may break symmetries and leads to novel topological phases.
Introducing non-Hermitian Floquet modulation enables more interesting phenomena including bandgap in imaginary part of the spectrum and gainy/lossy topological edge states with complex energy values. …
Wave Excitation And Dynamics In Disordered Systems, Yiming Huang
Wave Excitation And Dynamics In Disordered Systems, Yiming Huang
Dissertations, Theses, and Capstone Projects
This thesis presents studies of the field and energy excited in disordered systems as well as the dynamics of scattering.
Dynamic and steady state aspects of wave propagation are deeply connected in lossless open systems in which the scattering matrix is unitary. There is then an equivalence among the energy excited within the medium through all channels, the Wigner time delay, which is the sum of dwell times in all channels coupled to the medium, and the density of states. But these equivalences fall away in the presence of material loss or gain. In this paper, we use microwave measurements, …
Nonlinear Optical Studies Of Interfacial Ferroelectricity And Strain Distribution In Perovskite Dielectric Films, Tony Le
Dissertations, Theses, and Capstone Projects
Dielectric and ferroelectric perovskite films have been model energy storage structures for their low-dielectric loss, extremely high charge-discharge speed, and good temperature stability, yet there is still much to understand about the material’s limitations. This dissertation presents a detailed understanding of the strain-induced ferroelectricity at the boundary between a strontium titanate (SrTiO3) ultrathin film epitaxially grown on a germanium (Ge) substrate through optical second harmonic generation (SHG), and the polydomain distribution in the Zr-doped BaTiO3 (BZT) films by time-resolved pump-probe spectroscopy.
First, SHG measurements were performed to reveal interfacial ferroelectricity in the epitaxial SrTiO3/Ge (100) …
Diffraction-Based Studies Of Magneto- And Baro-Caloric Materials, Steven P. Vallone
Diffraction-Based Studies Of Magneto- And Baro-Caloric Materials, Steven P. Vallone
Dissertations, Theses, and Capstone Projects
The field of calorics represents a class of materials that offer the potential for solid-state cooling and heating, and, given the global climate crisis, comprise a necessary and active area of research. A clear and thorough understanding of their internal structural interactions and their external response to the environment is necessary for overall progress in the field, as accurate theoretical modeling and efficient materials design for devices both depend on this information. Through analysis of x-ray and neutron diffraction, the atomic order and disorder that drives these interactions is revealed. This dissertation focuses on diffraction studies concerning representative samples from …
Linear And Non Linear Properties Of Two-Dimensional Exciton-Polaritons, Mandeep Khatoniar
Linear And Non Linear Properties Of Two-Dimensional Exciton-Polaritons, Mandeep Khatoniar
Dissertations, Theses, and Capstone Projects
Technology has been accelerating at breakneck speed since the first quantum revolution, an era that ushered transistors and lasers in the late 1940s and early 1960s. Both of these technologies relied on a matured understanding of quantum theories and since their inception has propelled innovation and development in various sectors like communications, metrology, and sensing. Optical technologies were thought to be the game changers in terms of logic and computing operations, with the elevator pitch being "computing at speed of light", a fundamental speed limit imposed by this universe’s legal system (a.k.a physics). However, it was soon realized that that …
Quantum Transport In Topological Magnets, Haiming Deng
Quantum Transport In Topological Magnets, Haiming Deng
Dissertations, Theses, and Capstone Projects
In the past several years, a new field of symmetry-protected topological materials has emerged in condensed matter physics, based on the wide range of consequences that result from the realization that certain properties of physical systems can be expressed as topological invariants, which are insensitive to local perturbations. This new class of materials hosts unique surface/edge states, such as the first known topological system – quantum Hall insulator with dissipationless chiral edge states, and massless spin-helical Dirac surface states in 3D topological insulators that are unlike any other known 1D or 2D electronic systems. In this thesis, to understand the …
Skyrmions And Biskyrmions In Magnetic Films, Daniel Capic
Skyrmions And Biskyrmions In Magnetic Films, Daniel Capic
Dissertations, Theses, and Capstone Projects
Skyrmions have garnered significant attention in condensed matter systems in recent years. In principle, they are topologically protected, so there is a large energy barrier preventing their annihilation. Furthermore, they can exist at the nanoscale, be manipulated with very small currents, and be created by a number of different methods. This makes them attractive for use in potential computing applications. This work studies ferromagnetic skyrmions. In particular, it highlights our small contributions to the field of skyrmions in condensed matter systems, specifically in thin-film ferromagnets.
Optimization Of Materials For Magnetic Refrigeration And Thermomagnetic Power Generation, Anthony N. Tantillo
Optimization Of Materials For Magnetic Refrigeration And Thermomagnetic Power Generation, Anthony N. Tantillo
Dissertations, Theses, and Capstone Projects
The magnetocaloric effect, by which a magnetic material experiences a change in temperature due to an applied magnetic field, can be used for refrigeration. The corollary to the magnetocaloric effect -- known as the pyromagnetic effect -- is the phenomenon by which a magnetic material experiences a thermally-induced change in magnetization that can be used to harvest thermal energy. This dissertation has two main parts: one focusing on novel materials for energy harvesting; and another focusing on methods of materials discovery for refrigeration purposes. Thermomagnetic power generation (TMG) is the process by which magnetic flux, which comes from a temperature-driven …
Interactions Of Organic Fluorophores With Plasmonic Surface Lattice Resonances, Robert J. Collison
Interactions Of Organic Fluorophores With Plasmonic Surface Lattice Resonances, Robert J. Collison
Dissertations, Theses, and Capstone Projects
It is common knowledge that metals, alloys and pure elements alike, are lustrous and reflective, the more so when a metal surface is flat, polished, and free from oxidation and surface fouling. However, some metals reflect visible light, in the 380 nm to 740 nm range of wavelengths, much more strongly than others. In particular, some metals reflect wavelengths in certain portions of the ultraviolet (UV), visible, and near-infrared (NIR) regime, let us say 200 nm to 2000 nm, while absorbing light strongly in other segments of this range. There are several factors that account for this difference between various …