Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 61 for “"Ferroelectricity"”.
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Quantum Critical Ferroelectricity and Emergent Phenomena in KTaO3 and SrTiO3
This thesis explores the quantum phase diagrams of KTaO3 and SrTiO3, both quantum paraelectrics near to a ferroelectric quantum critical point, including study of material properties which may be influenced by proximity to a ferroelectric quantum phase transition. A quantum critical phase …
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Ferroelectricity Coupled To Octahedral Rotations In Perovskite Oxides From First Principles
… of physical properties. Some perovskites exhibit ferroelectricity, the existence of a field-switchable electric polarization. Other perovskites exhibit rotations of the oxygen octahedra, which buckles bonds and leads to rich phase diagrams of magnetic and electronic order. This thesis investigates …
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Effect of nonstoichiometry on the magnetism and ferroelectricity of Fe- and Co-substituted strontium titanate thin films
… memory. Room temperature ferromagnetism and ferroelectricity are of great interest to the multiferroic and magnetoelectric community, as a key challenge in the field is engineering a material exhibiting room temperature ferroelectricity and ferromagnetism. Pulsed laser deposition grown …
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First Principles Studies of Magnetic Oxides, Spin-Driven Ferroelectricity, and the Effect of Polarization in the Chemistry of Functional Heterointerfaces
Achieving accurate description and understanding of the chemical and physical properties of complex materials enables the further development of their technological applications. Employing density functional theory (DFT) with rotationally invariant Hubbard corrections, we present an extensive study …
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A Schottky-to-Ohmic Transition in Epitaxial Ferroelectric Hafnia Devices
… Both the migration of oxygen ions and ferroelectricity are two mechanisms actively being explored to drive resistance change in hafnia based devices. This thesis explores the interplay between interfacial redox chemistry and ferroelectricity and how these influence the resistance …
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Cation Site Occupancy and Defect Engineering in Perovskite Heterostructures
… thin films. We start with the generation of ferroelectricity in an antiferromagnet LuFeO₃ through cation antisite defects and concomitant inversion symmetry breaking. We elucidate how the crystal structure and ferroelectricity depend on cation stoichiometry. We then integrate this …
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Magneto-optical and multiferroic oxide thin films, integrated nonreciprocal photonic devices and multiferroic memory devices
… This perovskite oxide has been found to exhibit ferroelectricity and magnetism at room temperature. Experimental results on magnetism, ferroelectricity and structure were reproduced using density functional theory simulations.
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Structure-Function Relationships in Organic Charge-Transfer Complexes
… ambipolar semiconductivity, photoconductivity, ferroelectricity, and more. The focus of this work is to identify several structure-function relationships in charge-transfer complexes pertaining to organic field-effect transistors (OFETs). The materials of focus in these studies are perylene- …
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Doped HfO2 thin films: Engineering and Origins of its ferroelectric properties
… One of those physical phenomena of interest is ferroelectricity, capitalising on reversibly switchable polarisation with application of electric field. Especially, with the discovery of ferroelectricity in scalable and CMOS-compatible HfO2 thin film in which its polarisation amplifies with …
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Probing Nanoscale Functional Properties of Perovskite and Wurtzite Ferroelectrics via Scanning Probe Microscopy
… were employed to investigate the topography, ferroelectricity and conductivity of perovskite and wurtzite ferroelectric materials for prospective applications in science and technology. Ferroelectrics exhibit a switchable spontaneous polarization when subjected to an electric field and are …
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INVESTIGATION OF THE STRUCTURAL PROPERTIES OF HAFNIUM ZIRCONIUM OXIDE THIN FILMS
… Unlike in conventional ferroelectrics, ferroelectricity in HfxZr1-xO2 is retained in ultrathin films of only a few nanometers thickness. The ultrathin nature of these structures enables ferroelectric tunnel junctions with higher readout currents than FeRAM, and with non-destructive …
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In-situ plasmon-enhanced characterization of optically accessible ultra-thin film ferroelectric devices
… characterisation in this research. Chapter 2, Ferroelectricity and FeRAMs, presents the theory of ferroelectricity, emphasizing on Hafnium Oxide as a ferroelectric material. Chapter 3, Experimental Methods, describes the optical and electrical setup utilized in experiments. Scanning …
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Ab Initio study of dynamically tunable catalysis for carbon dioxide reduction
… In addition, we develop a scheme to induce ferroelectricity in ZnO films. If proven in the lab, this will be the first scheme to induce ferroelectricity in ZnO without relying on the involvement of dipole-inducing dopants. In addition, we show that this scheme allows for consistent surface …
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Structure, magnetism and multiferroicity in self-assembled oxide nanocomposites
… such as high conduction at interfaces, enhanced ferroelectricity and magnetoelectric coupling, which are often absent or occur at a lower magnitude in single phase materials. In particular, magnetoelectric multiferroics, materials that exhibit two or more ferroic orders (such as ferromagnetism …
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First-principles studies of perovskite thin films and heterostructures
… how strain and interfacial chemistry affect the ferroelectricity of BaTiO₃/Ge and BaTiO₃/SrTiO₃/Ge heterostructures. We also discuss the development of two-dimensional conducting states created in BaTiO₃/SrTiO₃ heterostructures.
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Processing and characterization of lithium niobate thin films for ferroelectric nonvolatile memory applications
… switching are observed, verifying the ferroelectricity of deposited LiNbO3 thin films. Comparison of different film growth mechanisms between these two deposition methods is made, and their effects on physical and electrical characteristics of the derived LiNbO3 thin films are …
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Grain size effect on structure and properties for chemically-prepared barium titanate
… below 0.5$\mu$m, and (iii) the concept that ferroelectricity should become unstable below a limiting critical crystallite size. This thesis reports an experimental investigation which substantially clarifies and leads to a plausible explanation of these phenomena for chemically prepared …
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Synthesis, Characterization and Applications of Europium Based Perovskite Oxide Nanoparticles
… large dielectric polarization, alongside ferroelectricity and ferromagnetism in low temperature. Most approaches to synthesize the EBTO systems lies in the solid-state reaction methods. However, here we used a chemical solution approach (referred to gel-collection method), which produces …
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Ferroelectric doped hafnium oxide and its application on electronic devices
Ferroelectricity is the material property such that we can induce spontaneous polarization, reverse it and modulate it by varying the applied electrical field on the ferroelectric material. Recently, doped hafnium oxide (HfO2) has garnered attention with its excellent scalability, reliability, and …
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