Download or read book Theoretical Study of Magnetic Topological Insulators written by 赵安 and published by . This book was released on 2013 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Theoretical Study of Magnetic Topological Insulators written by An Zhao and published by Open Dissertation Press. This book was released on 2017-01-26 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation, "Theoretical Study of Magnetic Topological Insulators" by An, Zhao, 赵安, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: In recent years, the discovery of topological insulators brought a topological classification of materials and opened a new field in condensed matter physics. Due to the nontrivial topological properties, the topological insulators have insulating bulk and metallic edge/surface relating to some exotic physics such as quantum anomalous Hall effect, quantum spin Hall effect, and magneto-electric effect. Followed realizations of the Z2 topological insulators in two and three dimensions, the quantum anomalous Hall effect was realized in the magnetic-doped topological insulators very recently, which attracts intensive interest. In this thesis, the magnetic topological insulators as a consequence of time-reversal symmetry breaking in the Z2 topological insulators in two or three dimensions are studied. As an introduction, a review of the topological insulators including some relevant theories is given. The approaches involved in this study are also presented. The results can be summarized in two parts. First, the quantum anomalous Hall effect can be found on the two-dimensional decorated lattice with spin-orbit coupling and electron-electron interaction. Without interaction, this model exhibits the quantum spin Hall effect and has at bands in the middle of the spectra. A at-band ferrimagnetism which breaks the time-reversal symmetry and a charge-density wave can be induced by the electron-electron interaction. Altogether they can modulate the Chern number of the system and give rise to the quantum anomalous Hall effect. In the second part, the realization of the quantum anomalous Hall effect in magnetic-doped topological insulator thin films is investigated. With an effective Hamiltonian of the surface states of a topological insulator thin _lm, the condition of the quantum anomalous Hall effect and the behavior of the longitudinal and Hall conductivity is given, which agrees with the experimental results. The effects of the structural inversion asymmetry potential and the particle-hole symmetry breaking term are studied. With a thin _lm model of the three-dimensional topological insulator, it is shown that the lateral surface states account for the non-quantized value of the Hall conductance and the nonzero longitudinal conductance. The quantized Hall conductance restores when the lateral surface state electrons are thoroughly localized by disorder. The quantum anomalous Hall phase in magnetic topological insulator thin film in the present of disorder is also studied. The disorder will shrink the regime of the quantum anomalous Hall effect in a thick film and becomes an obstacle to the realization of the quantum anomalous Hall effect. DOI: 10.5353/th_b5194784 Subjects: Condensed matter
Download or read book Topological Insulators and Topological Superconductors written by B. Andrei Bernevig and published by Princeton University Press. This book was released on 2013-04-07 with total page 264 pages. Available in PDF, EPUB and Kindle. Book excerpt: This graduate-level textbook is the first pedagogical synthesis of the field of topological insulators and superconductors, one of the most exciting areas of research in condensed matter physics. Presenting the latest developments, while providing all the calculations necessary for a self-contained and complete description of the discipline, it is ideal for graduate students and researchers preparing to work in this area, and it will be an essential reference both within and outside the classroom. The book begins with simple concepts such as Berry phases, Dirac fermions, Hall conductance and its link to topology, and the Hofstadter problem of lattice electrons in a magnetic field. It moves on to explain topological phases of matter such as Chern insulators, two- and three-dimensional topological insulators, and Majorana p-wave wires. Additionally, the book covers zero modes on vortices in topological superconductors, time-reversal topological superconductors, and topological responses/field theory and topological indices. The book also analyzes recent topics in condensed matter theory and concludes by surveying active subfields of research such as insulators with point-group symmetries and the stability of topological semimetals. Problems at the end of each chapter offer opportunities to test knowledge and engage with frontier research issues. Topological Insulators and Topological Superconductors will provide graduate students and researchers with the physical understanding and mathematical tools needed to embark on research in this rapidly evolving field.
Download or read book Theoretical and Experimental Study of Topological Invariants in Topological Crystalline Insulators written by Juan Sebastián Calderón García and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The topological crystalline Insulators (TCI) are topological materials with metallic surface states protected by a symmetry given by the crystalline structure, and not by the Time reversal one as in the usual topological insulators. These insulators, whose band structures are classified by new topological invariants, are the counterpart of the topological insulators but without the spin-orbit coupling being the principal aspect. In this work, a theoretical study on the present topological invariants is shown by means of experimental measurements in monocrystals of (Pb1-xSnx)Te which are grown for this project. Particularly, it is desired to understand the evolution with magnetic field of the Landau energy levels of this kind of topological insulators.
Download or read book Topology in Magnetism written by Jiadong Zang and published by Springer. This book was released on 2018-09-24 with total page 416 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents both experimental and theoretical aspects of topology in magnetism. It first discusses how the topology in real space is relevant for a variety of magnetic spin structures, including domain walls, vortices, skyrmions, and dynamic excitations, and then focuses on the phenomena that are driven by distinct topology in reciprocal momentum space, such as anomalous and spin Hall effects, topological insulators, and Weyl semimetals. Lastly, it examines how topology influences dynamic phenomena and excitations (such as spin waves, magnons, localized dynamic solitons, and Majorana fermions). The book also shows how these developments promise to lead the transformative revolution of information technology.
Download or read book Topological Insulators written by Naoto Nagaosa and published by Elsevier Inc. Chapters. This book was released on 2013-11-23 with total page 39 pages. Available in PDF, EPUB and Kindle. Book excerpt: The discovery of the rich topological structures of electronic states in solids has opened up many interesting possibilities. The “twist” of the wavefunctions in momentum space, which is characterized by topological invariants, leads to the robust edge or surface states. The electron fractionalization associated with these topological states brings about the novel physics such as absence of localization, topological magneto-electric effect, and Majorana fermions. Here we describe the principles and some concrete examples of the theoretical design of the topological materials and their functions based on these recent developments.
Download or read book Investigation of Magnetic Interactions in Topological Insulators written by Mingda Li (Ph. D.) and published by . This book was released on 2015 with total page 111 pages. Available in PDF, EPUB and Kindle. Book excerpt: Topological insulators are a category of phases in condensed matter with inverted conduction and valence bands, which is protected by time reversal symmetry. As a result, the bulk keeps insulating while the surface supports an exotic high-mobility spin-polarized electronic states. Introducing magnetism into topological insulators will break the surface time reversal symmetry and alter the spin texture at the surface, and is an essential step to bring topological insulators towards the observation of new quantum states and for device applications. This thesis is a comprehensive study of magnetic interactions in topological insulators, from both experimental and theoretical perspective. Generically, there are two approaches to bring TI magnetic, the proximity effect and the conventional transitional metal ion doping. In the proximity effect, a layer of magnetic insulator is in proximally contact with a topological insulator, which forms a heterostructure and introduces magnetic exchange with the topological insulator states; while in the transitional metal ion doping, the magnetic dopants will induce magnetic order inside topological insulators. The main content and contribution of this thesis are five-fold. First and foremost, this thesis provides conclusive experimental evidence to demonstrate a long-predicted new type of magnetism, the "Van Vleck ferromagnetism" in magnetic topological insulator Vanadium doped Sb2Te3. Compared with the traditional RKKY magnetism in diluted magnetic semiconductors which needs undesired free carriers to mediate the magnetism, such magnetism has an carrier-free origin and solves the dark current issue for spintronics applications, such as quantum anomalous Hall effect. Secondly, this thesis provides conclusive experimental evidence to demonstrate the magnetic proximity effect at topological insulator / ferromagnetic insulator interface, where magnetism is penetrated into the side of topological insulator. The main obstacle for this study is the inter-diffusion of magnetic ions to topological insulator, causing false positive signal. This is conquered through experimental means which is capable to resolve the layer-dependent compositional contrast as well as magnetization simultaneously. Thirdly, this thesis discusses a theoretical proposal to show that how to resolve the particular electronic state of topological insulator participating in the proximity effect. The determination of the magnetized electronic state of topological insulator turns out to be highly difficult for conventional experiments. We utilize the indirect interlayer exchange coupling, i.e. the magnetic coupling between two magnetic layers when a topological insulator is sandwiched in between, to demonstrate the possibility to resolve electronic state in a direct manner. The fourth point, this thesis also discusses a theoretical model to describe a plasmonic device based on topological insulator / superconductor hybrid structure, which has much low energy dissipation compared with metallic plasmon device and might be used to detect Majorana Fermions, an yet-to-be-confirmed particle as building block for quantum computation. Last but not least, combining the merits of high-Curie temperature of magnetic doping and the uniformity of magnetic proximity effect, we also report an enhanced proximity effect based on proximity induced coupling in magnetically doped topological insulator hybrid heterostructure.
Download or read book Magnetism in Topological Insulators written by Vladimir Litvinov and published by . This book was released on 2020 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This book serves as a brief introduction to topological insulator physics and device applications. Particular attention is paid to the indirect exchange interaction mediated by near surface Dirac fermions and the spin texture this interaction favors. Along with useful information on semiconductor material systems, the book provides a theoretical background for most common concepts of TI physics. Readers will benefit from up to date information and methods needed to start working in TI physics, theory, experiment and device applications. Discusses inter-spin interaction via massless and massive Dirac excitations;Includes coverage of near-surface spin texture of the magnetic atoms as related to their mutual positions as well to their positions with respect to top and bottom surfaces in thin TI film;Describes non-RKKY oscillating inter-spin interaction as a signature of the topological state;Explains the origin of the giant Rashba interaction at quantum phase transition in TI-conventional semiconductors.
Download or read book Magnetism in Topological Insulators written by Vladimir Litvinov and published by Springer. This book was released on 2019-05-07 with total page 163 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book serves as a brief introduction to topological insulator physics and device applications. Particular attention is paid to the indirect exchange interaction mediated by near surface Dirac fermions and the spin texture this interaction favors. Along with useful information on semiconductor material systems, the book provides a theoretical background for most common concepts of TI physics. Readers will benefit from up to date information and methods needed to start working in TI physics, theory, experiment and device applications. Discusses inter-spin interaction via massless and massive Dirac excitations; Includes coverage of near-surface spin texture of the magnetic atoms as related to their mutual positions as well to their positions with respect to top and bottom surfaces in thin TI film; Describes non-RKKY oscillating inter-spin interaction as a signature of the topological state; Explains the origin of the giant Rashba interaction at quantum phase transition in TI-conventional semiconductors.
Download or read book Theoretical Study of Topological Insulators written by and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 Topological Insulators written by Frank Ortmann and published by John Wiley & Sons. This book was released on 2015-04-07 with total page 434 pages. Available in PDF, EPUB and Kindle. Book excerpt: There are only few discoveries and new technologies in physical sciences that have the potential to dramatically alter and revolutionize our electronic world. Topological insulators are one of them. The present book for the first time provides a full overview and in-depth knowledge about this hot topic in materials science and condensed matter physics. Techniques such as angle-resolved photoemission spectrometry (ARPES), advanced solid-state Nuclear Magnetic Resonance (NMR) or scanning-tunnel microscopy (STM) together with key principles of topological insulators such as spin-locked electronic states, the Dirac point, quantum Hall effects and Majorana fermions are illuminated in individual chapters and are described in a clear and logical form. Written by an international team of experts, many of them directly involved in the very first discovery of topological insulators, the book provides the readers with the knowledge they need to understand the electronic behavior of these unique materials. Being more than a reference work, this book is essential for newcomers and advanced researchers working in the field of topological insulators.
Download or read book Topological Insulators written by Inamuddin and published by Materials Research Forum LLC. This book was released on 2024-01-15 with total page 195 pages. Available in PDF, EPUB and Kindle. Book excerpt: A topological insulator is an area that has yet to be fully explored and developed. The charge-induced bandgap fluctuation in the best-known bismuth-chalcogenide-based topological insulators is approximately 10MeV in magnitude. The major focus has shifted to the investigation of the presence of high-symmetry electronic bands as well as the utilization of easily produced materials. As the subject of topological insulators is still in the nascent stage, there is growing research and knowledge in the emerging field. This book is intended to provide the readers with an understanding of the needs and application of these materials. Keywords: Topological Insulators, Insulators, One-Dimensional Topological Insulators, Graphene, Magnetic Topological Insulator, Antiferromagnetic Phase, Ferromagnetic Phase, Topological Superconductor, Nonlinear Optical Behavior, Saturable Absorber, Quantum, Band Gap, Photonic Topological Insulators.
Download or read book Topological Quantum Numbers In Nonrelativistic Physics written by David Thouless and published by World Scientific. This book was released on 1998-03-12 with total page 440 pages. Available in PDF, EPUB and Kindle. Book excerpt: Topological quantum numbers are distinguished from quantum numbers based on symmetry because they are insensitive to the imperfections of the systems in which they are observed. They have become very important in precision measurements in recent years, and provide the best measurements of voltage and electrical resistance. This book describes the theory of such quantum numbers, starting with Dirac's argument for the quantization of electric charge, and continuing with discussions on the helium superfluids, flux quantization and the Josephson effect in superconductors, the quantum Hall effect, solids and liquid crystals, and topological phase transitions. The accompanying reprints include some of the classic experimental and theoretical papers in this area.Physicists — both experimental and theoretical — who are interested in the topic will find this book an invaluable reference.
Download or read book Studies on Time reversal Invariant Topological Insulators written by Joseph Maciejko and published by Stanford University. This book was released on 2011 with total page 242 pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation brings together a number of topics in the theory of time-reversal invariant topological insulators. The first four chapters are devoted to the transport properties of the two-dimensional (2D) quantum spin Hall state. We explain nonlocal transport measurements in mercury telluride (HgTe) quantum wells in terms of a Landauer-Büttiker theory of helical edge transport and confirm the discovery of the quantum spin Hall state in this material. We find that decoherence can lead to backscattering without breaking microscopic time-reversal symmetry. As an example of incoherent scattering, we study a Kondo impurity in an interacting helical edge liquid. A renormalization group analysis shows the existence of an impurity quantum phase transition governed by the Luttinger parameter of the edge liquid between a local helical Fermi liquid with T^6 scaling of the low-temperature conductance, and an insulating strongly correlated phase with fractionally charged emergent excitations. In the presence of a time-reversal symmetry breaking magnetic field, it is known that even coherent scattering can lead to backscattering. Through exact numerical diagonalization we find that nonmagnetic quenched disorder has a strong localizing effect on the edge transport if the disorder strength is comparable to the bulk gap. The predicted magnetoconductance agrees qualitatively with experiment. The last two chapters are devoted to 3D topological insulators. We propose a combined magnetooptical Kerr and Faraday rotation experiment as a universal measure of the Z_2 invariant. Finally, we propose a fractional generalization of 3D topological insulators in strongly correlated systems, characterized by ground state degeneracy on topologically nontrivial spatial 3-manifolds, a quantized fractional bulk magnetoelectric polarizability without time-reversal symmetry breaking, and a halved fractional quantum Hall effect on the surface.
Download or read book Glide Symmetric Z2 Magnetic Topological Crystalline Insulators written by Heejae Kim and published by Springer Nature. This book was released on 2022-01-25 with total page 171 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 Bulk and Boundary Invariants for Complex Topological Insulators written by Emil Prodan and published by Springer. This book was released on 2016-02-05 with total page 217 pages. Available in PDF, EPUB and Kindle. Book excerpt: This monograph offers an overview of rigorous results on fermionic topological insulators from the complex classes, namely, those without symmetries or with just a chiral symmetry. Particular focus is on the stability of the topological invariants in the presence of strong disorder, on the interplay between the bulk and boundary invariants and on their dependence on magnetic fields. The first part presents motivating examples and the conjectures put forward by the physics community, together with a brief review of the experimental achievements. The second part develops an operator algebraic approach for the study of disordered topological insulators. This leads naturally to the use of analytical tools from K-theory and non-commutative geometry, such as cyclic cohomology, quantized calculus with Fredholm modules and index pairings. New results include a generalized Streda formula and a proof of the delocalized nature of surface states in topological insulators with non-trivial invariants. The concluding chapter connects the invariants to measurable quantities and thus presents a refined physical characterization of the complex topological insulators. This book is intended for advanced students in mathematical physics and researchers alike.
