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 54 for “"Semimetal"”.
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CHARGE ORDER AND STRUCTURAL TRANSITION IN TOPOLOGICAL SEMIMETAL FAMILY AAL4
The BaAl$_4$-type structure hosts a variety of interesting and exotic properties, with descendant crystal structure resulting numerous interesting ground states of matter including magnetic, super-conducting and strongly correlated electron phenomena. BaAl$_4$ itself has recently been shown to host …
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COMPOSITION AND PRESSURE DEPENDENT STUDY ON WEYL SEMIMETAL Mo1-xWxTe2
… the doping and pressure effects on the Weyl semimetal Mo1−xWxTe2 have been investigated. A series of single crystals of Mo1−xWxTe2 for x = 0, 0.10, 0.30, 0.40, 0.50, 0.70, 0.75, 0.90, and 1 were synthesized using the self-flux method (for parent compounds MoTe2 and WTe2) and the chemical …
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Scanning tunneling microscopy studies of a tunable topological insulator and magnetic Weyl semimetal
… system Ge(Bix,Sb1-x)2Te4 and the magnetic Weyl semimetal Co3Sn2S2 were studied. In Ge(Bix,Sb1-x)2Te4, increasing Sb substitution effectively electron dopes the sample and moves the Dirac point from 300 meV below the Fermi energy to energies above the Fermi energy while remaining topological. As …
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A neutron diffraction study of the field-induced diamagnetism in the semimetal bismuth.
Thesis: Ph. D., Massachusetts Institute of Technology, Department of Physics, 1979
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Electronic properties of topological semimetal candidates ACd$_2$Pn$_2$ (A = Eu, Sr; Pn = As, Sb)
Weyl semimetals have attracted significant attention due to their intriguing electronic properties arising from the presence of Weyl points. Among them, ideal magnetic Weyl semimetals, characterized by a single pair of Weyl points close to the Fermi level, have long been sought for exploring the …
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Quantum oscillation studies in the unconventional superconductor YFe₂Ge₂ and in the Dirac semimetal candidates NbXSb (X = Ge/Si)
We have performed experiments to probe the ground state dynamics of YFe₂Ge₂, NbGeSb and NbSiSb. An unusually large Sommerfeld coefficient (γ ~ 100 mJmol⁻¹K⁻²) has been observed in the d-electron system YFe₂Ge₂. It also shows an anomalous power law temperature dependence of the electrical …
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An Investigation into Topological Crystals and Flat Band Systems
… the topological insulator Cu₂Ti, the Weyl semimetal VMg₂O₄, and the nodal semimetal PtSeTe. The flat band systems investigated all incorporate the 2-dimensional Kagome lattice in their 3-dimensional structures, and include the materials Zr₂Fe₃(Si,Ge) and Fe₆Ge₆Zr. Synthesis campaigns for …
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Magnetic Weyl Semimetals for Spintronic Applications
Magnetic Weyl semimetals are a category of topological materials that hold promise for spintronic applications due to their unconventional transport properties, which arise from both bulk and surface topological states, as well as the rich interplay between band topology and magnetism. Among the …
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Angle-resolved photoemission studies of topological thin films and superconducting heterostructures
… (Bi{1-x}Sbx)2Te3/Nb, and the Type-II Dirac semimetal candidate NiTe2. A major component of this thesis research was the engineering of clean, nearly intrinsic TI/SC systems to probe the mechanism of proximity-induced pairing in these systems. Interfacing a TI with a simple isotropic s-wave …
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Topological Phases in Perovskite Iridates with Strong Spin-Orbit Coupling
… are broken, including a Weyl and nodal-line semimetal. Secondly, we provide a generic condition to identify a novel three-dimensional topological semi-metallic phase in materials with strong spin-orbit coupling. Such a semi-metallic phase is featured by bulk gapless four-fold degenerate …
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Exploring linear and nonlinear electromagnetic responses in topological materials
… covered in this thesis are the conventional Weyl semimetal, the Kramers Weyl semimetal, and the moiré Chern insulator. We begin this research topic by understanding how charge-density waves impact electric field-induced transport in the topological system: the Weyl semimetal.Research over the past …
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Optical and electrical properties of narrow gap germanium-tin alloys with high tin contents for middle and far infrared applications
… expand on the current predictive models. ☐ Weyl semimetals are a new topological state of matter in semimetals without either spatial inversion or time-reversal symmetry, are characterized by their zero-energy, direct bandgaps, and exhibit novel electronic properties. An active area of research …
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Angle-resolved photoemission studies of thin-film topological materials
… Bi2Te3, and a newly discovered topological Dirac semimetal (TDS), α-Sn under suitable strain. TIs and TDSs have nontrivial surface states and unique bulk electronic structures. Because of that, they possess many unusual physical properties and are promising materials for realizing novel device …
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Angle-resolved photoemission and first-principles studies of topological semimetals and heterostructures
… study the electronic properties of topological semimetals and topological heterostructures. The topological heterostructures are prepared using molecular beam epitaxy (MBE) and characterized by experimental techniques such as reflective-high energy electron diffraction (RHEED) and low-energy …
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Probing the Dynamics of Pressure- and Magnetic Field -Tuned Transitions in Strongly-Correlated Electron Systems: Raman Scattering Studies
… a function of decreasing T: (i) a paramagnetic semimetal regime, characterized by a collision-dominated electronic scattering response whose scattering rate Gamma decreases with decreasing temperature; (ii) a spin-disorder scattering regime, characterized by a collision-dominated electronic …
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Surface studies of group IV-VI layered crystals
… radiation. The results indicate that TiSe2 a semimetal with a band overlap of less than 0.25 eV, while TiSi2 a semiconductor. These measured bands are in good agreement with recent theoretical band calculations.
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Nonreciprocal and Exotic Radiative Transfer in Type-I Magnetic Weyl Semimetals
… discovered family of quantum materials—Weyl semimetals—can possess intrinsic nonreciprocity due to the Berry curvature, an internal, pseudo-magnetic field. In this dissertation, we explore thermal radiation from type-I magnetic Weyl semimetals in planar configurations in the far- and …
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Patterns of electro-magnetic response in topological semi-metals
Topological semimetals are gapless states of matter which have robust and unique electromagnetic responses and surface states. In this thesis, we consider semimetals which have point like Fermi surfaces in various spatial dimensions $D=1,2,3$ which naturally occur in the transition between $n$th …
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Tailoring charge to spin conversion in novel materials for efficient spintronics
… order in the newly discovered magnetic Weyl semimetal (MWSM), Co₂MnGa, we can control the spin-charge conversion. Tailoring this interconversion efficiency will lead to energy-efficient and highly tunable memory and computing devices.
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Quantum oscillations in Dirac semimetals
Dirac semimetals have recently gained interest due to their unique experimental signatures many of which can be explained by the topologically non-trivial band structure in these materials. Among the many candidates, the tellurides NbTe₄, TaPtTe₅ and TaNiTe₅ appear to provide a promising platform …
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