Download or read book Reshaping of Dirac Cones in Topological Insulators and Graphene written by Álvaro Díaz Fernández and published by Springer Nature. This book was released on 2020-12-09 with total page 183 pages. Available in PDF, EPUB and Kindle. Book excerpt: Dirac cones are ubiquitous to non-trivial quantum matter and are expected to boost and reshape the field of modern electronics. Particularly relevant examples where these cones arise are topological insulators and graphene. From a fundamental perspective, this thesis proposes schemes towards modifying basic properties of these cones in the aforementioned materials. The thesis begins with a brief historical introduction which is followed by an extensive chapter that endows the reader with the basic tools of symmetry and topology needed to understand the remaining text. The subsequent four chapters are devoted to the reshaping of Dirac cones by external fields and delta doping. At all times, the ideas discussed in the second chapter are always a guiding principle to understand the phenomena discussed in those four chapters. As a result, the thesis is cohesive and represents a major advance in our understanding of the physics of Dirac materials.
Download or read book Reshaping of Dirac Cones in Topological Insulators and Graphene written by Álvaro Díaz Fernández and published by . This book was released on 2021 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Dirac cones are ubiquitous to non-trivial quantum matter and are expected to boost and reshape the field of modern electronics. Particularly relevant examples where these cones arise are topological insulators and graphene. From a fundamental perspective, this thesis proposes schemes towards modifying basic properties of these cones in the aforementioned materials. The thesis begins with a brief historical introduction which is followed by an extensive chapter that endows the reader with the basic tools of symmetry and topology needed to understand the remaining text. The subsequent four chapters are devoted to the reshaping of Dirac cones by external fields and delta doping. At all times, the ideas discussed in the second chapter are always a guiding principle to understand the phenomena discussed in those four chapters. As a result, the thesis is cohesive and represents a major advance in our understanding of the physics of Dirac materials.
Download or read book Strong and Weak Topology Probed by Surface Science written by Christian Pauly and published by Springer. This book was released on 2016-01-22 with total page 172 pages. Available in PDF, EPUB and Kindle. Book excerpt: Christian Pauly demonstrates the strong topological properties of the technologically relevant phase change materials Sb2Te3 and Ge2Sb2Te5 by using two powerful techniques for mapping the surface electronic structure: scanning tunneling spectroscopy (STS) and angle-resolved photoemission spectroscopy (ARPES). In the case of a phase change material, this opens up the possibility of switching between an insulating amorphous and a conducting topological phase on nanosecond-time scales. Moreover, the author presents first experimental results of a weak topological insulator, namely on the bismuth-based graphene-like sheet system Bi14Rh3I9, revealing a topologically protected one-dimensional edge channel as its fingerprint. The edge state is as narrow as 0.8 nm, making it extremely attractive to device physics. Those strong and weak topological insulators are a new phase of quantum matter giving rise to robust boundary states which are protected from backscattering and localization.
Download or read book Theoretical Study on Correlation Effects in Topological Matter written by Hiroki Isobe and published by Springer. This book was released on 2017-04-04 with total page 143 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis elucidates electron correlation effects in topological matter whose electronic states hold nontrivial topological properties robust against small perturbations. In addition to a comprehensive introduction to topological matter, this thesis provides a new perspective on correlated topological matter. The book comprises three subjects, in which electron correlations in different forms are considered. The first focuses on Coulomb interactions for massless Dirac fermions. Using a perturbative approach, the author reveals emergent Lorentz invariance in a low-energy limit and discusses how to probe the Lorentz invariance experimentally. The second subject aims to show a principle for synthesizing topological insulators with common, light elements. The interplay between the spin–orbit interaction and electron correlation is considered, and Hund's rule and electron filling are consequently found to play a key role for a strong spin–orbit interaction important for topological insulators. The last subject is classification of topological crystalline insulators in the presence of electron correlation. Unlike non-interacting topological insulators, such two- and three-dimensional correlated insulators with mirror symmetry are demonstrated to be characterized, respectively, by the Z4 and Z8 group by using the bosonization technique and a geometrical consideration.
Download or read book 2D Dirac Materials written by Desalegne Bekuretsion Teweldebrhan and published by . This book was released on 2011 with total page 120 pages. Available in PDF, EPUB and Kindle. Book excerpt: Silicon has been reaching physical limits as the semiconductor industry moves to smaller device feature sizes, increased integration densities and faster operation speeds. There is a strong need to engineer alternative materials, which can become foundation of new computational paradigms or lead to other applications such as efficient solid-state energy conversion. Recently discovered Dirac materials, which are characterized by the liner electron dispersion, are examples of such alternative materials. In this dissertation, I investigate two representatives of Dirac materials - graphene and topological insulators. Specifically, I focus on the (i) effects of electron beam irradiation on graphene properties and (ii) electronic and thermal characteristics of exfoliated films of Bi [subscript 2] Te [subscript 3] -family of topological insulators. I carried out Raman investigation of changes in graphene crystal lattice induced by the low and medium energy electron-beam irradiation (5.20 keV). It was found that radiation exposures result in appearance of the disorder D band around 1345 cm [superscript -1]. The dependence of the ratio of the intensities of D and G peaks, I(D)/I(G), on the irradiation dose is non-monotonic suggesting graphene.s transformation to polycrystalline and then to disordered state. By controlling the irradiation dose one can change the carrier mobility and increase the resistance at the minimum conduction point. The obtained results may lead to new methods of defect engineering of graphene properties. They also have important implications for fabrication of graphene nanodevices, which involve electron beams. Bismuth telluride and related compounds are the best thermoelectric materials known today. Recently, it was determined that they reveal the topological insulator properties. We succeeded in the first "graphene-like" exfoliation of large-area crystalline films and ribbons of Bi [subscript 2] Te [subscript 3] with the thickness going down to a single quintuple. The presence of van der Waals gaps allowed us to disassemble Bi [subscript 2] Te [subscript 3] crystal into the five mono-atomic sheets consisting of Te [superscript (1)] -Bi-Te [superscript (2)] -Bi-Te [superscript (1)]. The exfoliated films had extremely low thermal conductivity and electrical resistance in the range required for thermoelectric applications. The obtained results may pave the way for producing Bi [subscript 2] Te [subscript 3] films and stacked superlattices with strong quantum confinement of charge carriers and predominantly surface transport, and allow one to obtain theoretically predicted order-of-magnitude higher thermoelectric figure-of-merit.
Download or read book Topological States of Matter written by Vincenzo Parente and published by LAP Lambert Academic Publishing. This book was released on 2013 with total page 180 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract from dissertation: My research program is focused on the study of elastic deformation and topological defects in two materials: graphene and topological insulators. In both systems at low energies the electrons have a nearly linear spectrum, i.e. they behave like relativistic fermions. This allows the study of the effects of defects and deformations on the dynamics of electrons trough the formalism of Dirac equation on curved space-time. In this setting it's possible to derive correction to observables properties of the systems like the conductivity for example. In the case of graphene I have derived the contribution to conductivity in the Born approximation of the metric arising from the so-called bumps and made a comparison with the scattering on the gauge potential arising from the elastic deformation. A particular defect, the edge dislocation, is found to be a possible responsible for the behaviour of the conductivity at low energies. The topological insulators are a class of band insulators showing gapless edge states, capable of conduction. This situation is similar to Quantum Hall Effect, both physically and formally. Indeed, as in QHE topological invariants (Chern numbers) classify the behaviour of the material. I am thus focused on the study of these material both formally, on the ground of differential geometry, and physically, studying topological defect in topological insulators. Further investigation has been devoted to the analysis of electron-phonon interaction at the surface of a 3D TI, analysing superconductive instability.
Download or read book Single Dirac Cone Topological Surface State and Unusual Thermoelectric Property of Compounds from a New Topological Insulator Family written by and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Angle resolved photoemission spectroscopy (ARPES) study on TlBiTe2 and TlBiSe2 from a Thallium-based III-V-VI2 ternary chalcogenides family revealed a single surface Dirac cone at the center of the Brillouin zone for both compounds. For TlBiSe2, the large bulk gap (≈ 200meV) makes it a topological insulator with better mechanical properties than the previous binary 3D topological insualtor family. For TlBiTe2, the observed negative bulk gap indicates it as a semi-metal, rather than a narrow gap semi-conductor as conventionally believed; this semi-metality naturally explains its mysteriously small thermoelectric figure of merit comparing to other compounds in the family. Finally, the unique band structures of TlBiTe2 also suggests it as a candidate for topological superconductors.
Download or read book Dirac Cones in Germanene PT 111 written by Carmel Dansou and published by . This book was released on 2018 with total page 80 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Two photon Photoemission Studies of Graphene and Topological Insulators written by Daniel Niesner and published by . This book was released on 2013 with total page 117 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Berry Phases in Electronic Structure Theory written by David Vanderbilt and published by Cambridge University Press. This book was released on 2018-11 with total page 395 pages. Available in PDF, EPUB and Kindle. Book excerpt: An introduction to the role of Berry phases in our modern understanding of the physics of electrons in solids.
Download or read book Characterization and Modification of Graphene Based Interfacial Mechanical Behavior written by Guorui Wang and published by Springer. This book was released on 2020-08-22 with total page 139 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis shares new findings on the interfacial mechanics of graphene-based materials interacting with rigid/soft substrate and with one another. It presents an experimental platform including various loading modes that allow nanoscale deformation of atomically thin films, and a combination of atomic force microscopy (AFM) and Raman spectroscopy that allows both displacement and strain to be precisely measured at microscale. The thesis argues that the rich interfacial behaviors of graphene are dominated by weak van der Waals force, which can be effectively modulated using chemical strategies. The continuum theories are demonstrated to be applicable to nano-mechanics and can be used to predict key parameters such as shear/friction and adhesion. Addressing key interfacial mechanics issues, the findings in thesis not only offer quantitative insights in the novel features of friction and adhesion to be found only at nanoscale, but will also facilitate the deterministic design of high-performance graphene-based nanodevices and nanocomposites.
Download or read book Glide Symmetric Z2 Magnetic Topological Crystalline Insulators written by Heejae Kim and published by Springer. This book was released on 2023-01-27 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents a comprehensive theory on glide-symmetric topological crystalline insulators. Beginning with developing a theory of topological phase transitions between a topological and trivial phase, it derives a formula for topological invariance in a glide-symmetric topological phase when inversion symmetry is added into a system. It also shows that the addition of inversion symmetry drastically simplifies the formula, providing insights into this topological phase, and proposes potential implementations. Lastly, based on the above results, the author establishes a way to design topological photonic crystals. Allowing readers to gain a comprehensive understanding of the glide-symmetric topological crystalline insulators, the book offers a way to produce such a topological phase in various physical systems, such as electronic and photonic systems, in the future.
Download or read book Electrodynamics of Solids written by Martin Dressel and published by Cambridge University Press. This book was released on 2002-01-17 with total page 490 pages. Available in PDF, EPUB and Kindle. Book excerpt: The authors of this book present a thorough discussion of the optical properties of solids, with a focus on electron states and their response to electrodynamic fields. A review of the fundamental aspects of the propagation of electromagnetic fields, and their interaction with condensed matter, is given. This is followed by a discussion of the optical properties of metals, semiconductors, and collective states of solids such as superconductors. Theoretical concepts, measurement techniques and experimental results are covered in three interrelated sections. Well-established, mature fields are discussed (for example, classical metals and semiconductors) together with modern topics at the focus of current interest. The substantial reference list included will also prove to be a valuable resource for those interested in the electronic properties of solids. The book is intended for use by advanced undergraduate and graduate students, and researchers active in the fields of condensed matter physics, materials science and optical engineering.
Download or read book Plasmonics and Plasmonic Metamaterials written by Gennady Shvets and published by World Scientific. This book was released on 2012 with total page 469 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is a collection of the works of leading experts worldwide in the rapidly developing fields of plasmonics and metamaterials. These developments are promising to revolutionize ways of generating, controlling and processing light in the nanoscale. The technological applications range from nano-lasers to optical nano-waveguides to artificial media with unusual and exotic optical properties unattainable in natural materials. The volume cuts across all relevant disciplines and covers experiments, measurements, fabrication, physical and mathematical analysis, as well as computer simulation.
Download or read book Two Dimensional Transition Metal Dichalcogenides written by Narayanasamy Sabari Arul and published by Springer. This book was released on 2019-08-09 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents advanced synthesis techniques adopted to fabricate two-dimensional (2D) transition metal dichalcogenides (TMDs) materials with its enhanced properties towards their utilization in various applications such as, energy storage devices, photovoltaics, electrocatalysis, electronic devices, photocatalysts, sensing and biomedical applications. It provides detailed coverage on everything from the synthesis and properties to the applications and future prospects of research in 2D TMD nanomaterials.
Download or read book Quantum Fields on a Lattice written by Istvan Montvay and published by Cambridge University Press. This book was released on 1994 with total page 512 pages. Available in PDF, EPUB and Kindle. Book excerpt: Presents a comprehensive and coherent account of the theory of quantum fields on a lattice.
Download or read book The Physics of Graphene written by Mikhail I. Katsnelson and published by Cambridge University Press. This book was released on 2020-03-19 with total page 441 pages. Available in PDF, EPUB and Kindle. Book excerpt: Leading graphene research theorist Mikhail I. Katsnelson systematically presents the basic concepts of graphene physics in this fully revised second edition. The author illustrates and explains basic concepts such as Berry phase, scaling, Zitterbewegung, Kubo, Landauer and Mori formalisms in quantum kinetics, chirality, plasmons, commensurate-incommensurate transitions and many others. Open issues and unsolved problems introduce the reader to the latest developments in the field. New achievements and topics presented include the basic concepts of Van der Waals heterostructures, many-body physics of graphene, electronic optics of Dirac electrons, hydrodynamics of electron liquid and the mechanical properties of one atom-thick membranes. Building on an undergraduate-level knowledge of quantum and statistical physics and solid-state theory, this is an important graduate textbook for students in nanoscience, nanotechnology and condensed matter. For physicists and material scientists working in related areas, this is an excellent introduction to the fast-growing field of graphene science.
