Download or read book Effects of Surface Roughness on Transport Properties of Dirac Fermions on Topological Insulators written by 張東英 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 Topological Insulators written by and published by Elsevier. This book was released on 2013-11-23 with total page 349 pages. Available in PDF, EPUB and Kindle. Book excerpt: Topological Insulators, volume six in the Contemporary Concepts of Condensed Matter Series, describes the recent revolution in condensed matter physics that occurred in our understanding of crystalline solids. The book chronicles the work done worldwide that led to these discoveries and provides the reader with a comprehensive overview of the field. Starting in 2004, theorists began to explore the effect of topology on the physics of band insulators, a field previously considered well understood. However, the inclusion of topology brings key new elements into this old field. Whereas it was thought that all band insulators are essentially equivalent, the new theory predicts two distinct classes of band insulators in two spatial dimensions and 16 classes in three dimensions. These "topological" insulators exhibit a host of unusual physical properties, including topologically protected gapless surface states and exotic electromagnetic response, previously thought impossible in such systems. Within a short time, this new state of quantum matter, topological insulators, has been discovered experimentally both in 2D thin film structures and in 3D crystals and alloys. It appears that topological insulators are quite common in nature, and there are dozens of confirmed substances that exhibit this behavior. Theoretical and experimental studies of these materials are ongoing with the goal of attaining the fundamental understanding and exploiting them in future practical applications. Usable as a textbook for graduate students and as a reference resource for professionals Includes the most recent discoveries and visions for future technological applications All authors are prominent in the field
Download or read book Topological Insulators written by Jeroen B. Oostinga and published by Elsevier Inc. Chapters. This book was released on 2013-11-23 with total page 48 pages. Available in PDF, EPUB and Kindle. Book excerpt: The discovery of topological insulators as a new state of matter has generated immense interest in this new class of materials. Three-dimensional (3D) topological insulators are characterized by the presence of an odd number of families of Dirac fermions—ideally one- at each of their surfaces. Angle-resolved photoemission experiments have demonstrated the presence of the expected Dirac fermions, but it is clear that to explore the electronic properties of these systems, transport measurements in many different device geometries are called for, just as it has been the case for Dirac fermions in graphene. In this chapter we review the status of transport studies through 3D topological insulators as of early summer 2012, after that a first generation of experiments has been performed. The results provide many different indications of the presence of surface fermions, as well as evidence of their Dirac nature. However, no textbook “manifestation” of surface Dirac fermions has been reported so far in these materials. Indeed, experiments also show that investigations are severely hampered by the material quality in most cases, because of the effect of high conductivity in the bulk, of low carrier mobility, of technical difficulties hampering device fabrication, and other reasons. In this chapter, we attempt to give a balanced overview of the work done during this first period and of the results obtained, stressing the implications and the limits of many of the observations that have been reported in the literature.
Download or read book Topological Insulators written by Joel E. Moore and published by Elsevier Inc. Chapters. This book was released on 2013-11-23 with total page 31 pages. Available in PDF, EPUB and Kindle. Book excerpt: The theory of the topological insulator phase that emerges via spin-orbit coupling in three-dimensional materials is introduced, stressing its relationship to earlier topological phases in two dimensions. An unusual surface state with an odd number of “Dirac points” appears as a consequence of bulk topological invariants of the band structure. A different theoretical approach is then presented, based on the Berry phase of Bloch electrons, in order to illustrate a deep connection to the orbital contribution to the magnetoelectric polarizability in all materials. The unique features of transport in the topological insulator surface state are reviewed with an emphasis on possible experiments. The final section discusses briefly connections to interacting phases including topological superconductors and some recent efforts to construct fractional topological insulators in three dimensions.
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 Transport of dirac fermions on the surface of strong topological insulator and graphene written by Arijit Kundu and published by . This book was released on 2012 with total page 137 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Topological Insulator and Related Topics written by and published by Academic Press. This book was released on 2021-09-24 with total page 240 pages. Available in PDF, EPUB and Kindle. Book excerpt: Topological Insulator and Related Topics, Volume 108 in the Semiconductors and Semimental series, highlights new advances in the field, with this new volume presenting interesting chapters on topics such as Majorana modes at the ends of one dimensional topological superconductors, Optical/electronic properties of Weyl semimetals, High magnetic fields to unveil the electronic structure, magnetic field-induced transitions, and unconventional transport properties of topological semimetals, New aspects of strongly correlated superconductivity in the nearly flat-band regime, Anomalous transport properties in topological semimetals, Pseudo-gauge field and piezo-electromagnetic response in topological materials, Topological Gapped States Protected by Spatial Symmetries, and more. Provides the authority and expertise of leading contributors from an international board of authors Presents the latest release in the Semiconductors and Semimetals series Updated release includes the latest information on Topological Insulator and Related Topics
Download or read book Topological Insulators written by Haim Beindenkopf and published by Elsevier Inc. Chapters. This book was released on 2013-11-23 with total page 35 pages. Available in PDF, EPUB and Kindle. Book excerpt: Topological insulators are materials in which spin-orbit coupling is strong enough as to invert the ordering of bulk bands about the insulating bulk gap. While the bulk properties of these materials are not much different than any other insulating material their topological classification ensures the existence of exotic states on their surfaces. These surface electrons behave as massless relativistic particles obeying Dirac dynamics which locks their spin degree of freedom to their momentum thus reducing by half their phase space relative to any other fermionic state. Furthermore, the helical spin-texture associated with their Dirac nature greatly restricts scattering of surface states as long as time-reversal symmetry is preserved. In particular it forbids backscattering and therefore immunes the topological surface electrons from localizing. Scanning tunneling microscopy (STM) and spectroscopic mappings have played a key role in the characterization of these unique properties of the topological surface states. By visualizing electronic standing wave patterns next to impurities it was verified that the helical surface states do not backscatter. On the other hand, the Dirac electrons were found to be susceptible to the electrostatic charging of these scaterres, which induce spatial fluctuation of the Dirac energy and spectrum. Nevertheless, the unusual resilience of the helical surface states to disorder was strikingly demonstrated by measuring their high transmittance in an atomic-scale Fabry-Perot interferometry set up. The latter is a consequence of the existence of the topological surface states on all surface terminations which stems directly from the bulk topological classification. In the following chapter these insightful contributions of STM to the field of topological insulators will be discussed in detail alongside with future directions.
Download or read book Transport Properties of Dirac Fermions in Two Dimensions written by Ashley M. Dasilva and published by . This book was released on 2012 with total page 127 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Reflectionless Transport of Surface Dirac Fermions on Topological Insulators with Induced Ferromagnetic Domain Walls written by Christian Wickles and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 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 Two Dimensional Dirac Fermions in a Topological Insulator written by and published by . This book was released on 2011 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: Pulsed magnetic fields of up to 55T are used to investigate the transport properties of the topological insulator Bi2Se3 in the extreme quantum limit. For samples with a bulk carrier density of n = 2.9 x 1016 cm−3, the lowest Landau level of the bulk 3D Fermi surface is reached by a field of 4T. For fields well beyond this limit, Shubnikov-de Haas oscillations arising from quantization of the 2D surface state are observed, with the? = 1 Landau level attained by a field of H"35T. These measurements reveal the presence of additional oscillations which occur at fields corresponding to simple rational fractions of the integer Landau indices.
Download or read book Ultrafast Study of Dirac Fermions in Topological Insulators written by Lama Khalil and published by . This book was released on 2018 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis presents an experimental study of the electronic properties of two topological materials, namely, the irradiated three-dimensional topological insulator Bi2Te3 and the natural topological superlattice phase Sb2Te. Both systems were investigated by techniques based on photoemission spectroscopy. The Bi2Te3 compounds have been irradiated by high-energy electron beams. Irradiation with electron beams is a very promising approach to realize materials that are really insulating in the bulk, in order to emphasize the quantum transport in the protected surface states. By studying a series of samples of Bi2Te3 using time- and angle-resolved photoemission spectroscopy (trARPES) we show that, while the topological properties of the Dirac surface states are preserved after electron irradiation, their ultrafast relaxation dynamics are very sensitive to the related modifications of the bulk properties. Furthermore, we have studied the occupied and unoccupied electronic band structure of Sb2Te. Using scanning photoemission microscopy (SPEM), we have consistently found various nonequivalent regions on the same surface after cleaving several Sb2Te single crystals. We were able to identify three distinct terminations characterized by different Sb/Te surface stoichiometric ratios and with clear differences in their band structure. For the dominating Te-rich termination, we also provided a direct observation of the excited electronic states and of their relaxation dynamics by means of trARPES. Our results clearly indicate that the surface electronic structure is strongly affected by the bulk properties of the superlattice. Therefore, for both systems, we show that the surface electronic structure is absolutely connected to the bulk properties.
Download or read book Spin Helical Dirac Fermions in 3D Topological Insulator Quantum Wires written by Romain Giraud and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The next generation of electronic devices based on 3D topological insulators will be developed from advanced functional nanostructures and heterostructures. Toward this goal, single-crystalline nanowires offer interesting opportunities for new developments due to the strong quantum confinement of spin-helical surface Dirac fermions and to the possibility to realize core-shell lateral nanostructures adapted to the control of the electro-chemical potential at the interface with a topological insulator. Here, we review the specific transport properties of 3D topological insulator quantum wires and the influence of disorder. Having a large energy quantization, weakly-coupled Dirac surface modes are prone to quasi-ballistic transport, with some analogies to carbon nanotubes but with spin-textured quantum states weakly coupled by non-magnetic disorder. Due to a small interaction with their environment, these surface modes are good candidates to realize novel quantum spintronic devices, spanning from ballistic spin conductors to localized spin filters. A specific topological mode also holds promises to control chiral edge states and Majorana bound states in truly 1D quantum wires, being tunable with a magnetic field or an electrical gate. Challenges toward these goals are briefly discussed, as well as the need for novel functional heterostructures.
Download or read book Topological Insulators written by Gregory Tkachov and published by Pan Stanford. This book was released on 2015-09-30 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book came into being under the influence of dynamic developments that have occurred in condensed matter physics after the recent discovery of a new class of electronic materials called topological insulators. A topological insulator is a material that behaves as a band insulator in its interior, while acting as a metallic conductor at its surface. The surface current carriers in these systems have Dirac-like nature and are protected by an intrinsic topological order, which is of great interest for both fundamental research and emerging technologies, especially, in the fields of electronics, spintronics, and quantum information. The realization of the application potential of topological insulators requires a comprehensive and deep understanding of transport processes in these novel materials. The book explores the origin of the protected Dirac-like states in topological insulators and gives insight into some of their representative transport properties. These include the quantum spin–Hall effect, nonlocal edge transport, backscattering of helical edge and surface states, weak antilocalization, unconventional triplet p-wave superconductivity, topological bound states, and emergent Majorana fermions in Josephson junctions, as well as superconducting Klein tunneling.
Download or read book Quantum Transport of Two species Dirac Fermions in Dual gated Three dimensional Topological Insulators written by and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Topological insulators are a novel class of quantum matter with a gapped insulating bulk, yet gapless spin-helical Dirac fermion conducting surface states. Here, we report local and non-local electrical and magneto transport measurements in dual-gated BiSbTeSe2 thin film topological insulator devices, with conduction dominated by the spatially separated top and bottom surfaces, each hosting a single species of Dirac fermions with independent gate control over the carrier type and density. We observe many intriguing quantum transport phenomena in such a fully tunable two-species topological Dirac gas, including a zero-magnetic-field minimum conductivity close to twice the conductance quantum at the double Dirac point, a series of ambipolar two-component half-integer Dirac quantum Hall states and an electron-hole total filling factor zero state (with a zero-Hall plateau), exhibiting dissipationless (chiral) and dissipative (non-chiral) edge conduction, respectively. As a result, such a system paves the way to explore rich physics, ranging from topological magnetoelectric effects to exciton condensation.
