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 16 of 16 for “"Weyl semimetals"”.
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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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DEGENERATE SECOND ORDER NONLINEAR OPTICAL SPECTROSCOPY OF CHIRAL WEYL SEMIMETALS
… the measurement of topological properties of the Weyl semimetals. The first portion of this thesis describes technical developments of the nonlinear optical spectroscopic probes rotational anisotropy second harmonic generation (RA-SHG) and transient grating. In our work on SHG, we describe a …
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Nonreciprocal and Exotic Radiative Transfer in Type-I Magnetic Weyl Semimetals
… recently 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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Determination of Realistic Effective Models for Weyl Semimetals of the TaAs Family
… insulators with the material family Bi2Se3 and Weyl semimetals with the material family TaAs as concrete application examples. After a detailed introduction into the peculiarities of topological quantum materials, the essential physical properties of topological insulators and Weyl semimetals …
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Development of Broadband Time-Resolved Spectroscopy and Investigation of the Dynamics of Photoexcited Carriers and Lattice Excitations in Chiral Weyl Semimetals
… carriers and topological phonons in chiral Weyl semimetals. In the first portion of this thesis, we describe a novel, optical pump supercontinuum probe technique based upon a nonlinear photonic crystal fiber and a digital micro-mirror device enabling the use of single element detector and …
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Higher-order topological phases with crystalline symmetries
… states. We then study the gapless topological semimetals having crystalline symmetries. We identify a new type of Weyl semimetals, the higher-order Weyl semimetal (HOWSM), which hosts arc-like gapless states at both the surfaces and the hinges in a bounded 3D lattice. A 2nd-order Weyl node can …
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Genetic algorithm gradient ascent (GAGA) optimization of compact symmetry-breaking photonic crystals
… thesis presents 1D photonic crystals composed of Weyl/Dirac semimetal and dielectric layers, whose structures are optimized to maximize the nonreciprocity of infrared radiation absorptance/emittance in planar and compact designs. Two different mechanisms to enable nonreciprocal infrared …
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Exploring linear and nonlinear electromagnetic responses in topological materials
… are 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 …
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Optical and electrical properties of narrow gap germanium-tin alloys with high tin contents for middle and far infrared applications
… and 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 …
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Implications of Vorticity and Disorder on Quantum Transport in Topological Semimetals
… vortical and converse vortical effects in Weyl semimetals that break inversion symmetry. Using semiclassical and quantum kinetic frameworks, we analyze how Berry curvature and orbital magnetic moments generate charge and current responses in the presence of rotation and vorticity. The …
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Quantum Transport in Topological Phases of Matter
… of extrinsic Nernst effect in Dirac and Weyl semimetals, providing interpretation of existing experimental results and predictions for new enhanced responses in materials such as Fe3Sn2. In the following section, I demonstrate that a strong disorder can lead to a novel behavior of Dirac …
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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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Geometry and topological phase of matter
… I investigate the geometry related issues in Weyl semimetals and SPT states, and explore the novel character of geometry defect in SPT states inherited from the topological nature of manybody system. In addition, I would introduce a general way to induce topological phase transition via …
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Engineering relativistic fermions in condensed matter systems
… predicted in doped inversion symmetric Weyl semimetals (WSM). Using a four terminal measurement configuration, we show that the nodal points may be shifted and induce a topological phase transition by an application of transverse uniform current in doped WSM. We analyze the topological …
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Scanning tunneling microscopy and spectroscopy study of phase transitions and topology in layered transition metal dichalcogenides
… charge density wave (CDW), Mott physics, Weyl fermions and others. This class of materials has been known for decades but it received a renovated interest after the discovery of graphene and the development of tools to isolate single layers from layered materials. TMDs are suitable for …
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Examining Topological Insulators and Topological Semimetals Using First Principles Calculations
… surface states of topological insulators and semimetals. Topological materials have protected qualities which are not removed by weak perturbations. The manifestations of these qualities in topological insulators are spin-momentum-locked surface states, and in Weyl and Dirac semimetals they …