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Author: Andrew Patton Weber Publisher: ISBN: Category : Bismuth Languages : en Pages : 148
Book Description
As the size of a solid shrinks, the ratio of surface area to bulk volume grows and surface effects become more important. In a world where technologies advance with the shrinking size of electronic devices, one phase of matter has emerged which is fit for the near future of surface-dominated performance. Moreover, it has brought a new set of ideas to solid-state physics and chemistry, especially the understanding that the discipline of topology can be applied to classify the electron band structures. The topological insulator phase yields an exotic metal surface state in which the orientation of the electron's spin is locked perpendicular to its momentum. This property suppresses backscattering (making it possible to pass spin-polarized currents through the material without loss), offers a crucial ingredient for innovative approaches to quantum computation, and provides the basis for observing unique magnetoelectric effects. However, the surface states of materials in the topological insulator phase can wildly differ, so it is of interest to systematically characterize new materials to understand how the structure in position-space is related to the spin-resolved structure of electrons in energy- and momentum-space. We will discuss this relationship as it is probed through spin- and angle-resolved photoemission spectroscopy experiments on three topological (Bi2)m(Bi2Se3)n superlattices: (a) Bi2Se3 (m = 0, n = 1), (b) Bi4Se3 (m = 1, n = 1), and (c) BiSe (m = 1, n = 2). Our studies have not only proven the topological nature of these materials, but also demonstrate how bulk band structure and polar chemical bonding control the surface meta's concentration, dispersion, and spin-orbital character. Case (a) is considered to provide an ideal model of the topological surface metal. Case (b) provides the three important findings: (1) the chemical identity of the surface-termination controls the orbital composition and energy distribution of the surface states, (2) there are two topological states in sequential bulk band gaps, (3) of these, one of topological state undergoes a hybridization effect that yields a momentum-dependent gap in the band structure as large as 85 meV. Case (c) has a practical significance in that the surface metal has a potentially record-breaking carrier density of ~1013cm−2 (estimated from the Fermi surface area), more than an order of magnitude higher than in Bi2Se3. This occurs as a result of charge transfer from the Bi2 layers to the Bi2Se3 layers.
Author: Andrew Patton Weber Publisher: ISBN: Category : Bismuth Languages : en Pages : 148
Book Description
As the size of a solid shrinks, the ratio of surface area to bulk volume grows and surface effects become more important. In a world where technologies advance with the shrinking size of electronic devices, one phase of matter has emerged which is fit for the near future of surface-dominated performance. Moreover, it has brought a new set of ideas to solid-state physics and chemistry, especially the understanding that the discipline of topology can be applied to classify the electron band structures. The topological insulator phase yields an exotic metal surface state in which the orientation of the electron's spin is locked perpendicular to its momentum. This property suppresses backscattering (making it possible to pass spin-polarized currents through the material without loss), offers a crucial ingredient for innovative approaches to quantum computation, and provides the basis for observing unique magnetoelectric effects. However, the surface states of materials in the topological insulator phase can wildly differ, so it is of interest to systematically characterize new materials to understand how the structure in position-space is related to the spin-resolved structure of electrons in energy- and momentum-space. We will discuss this relationship as it is probed through spin- and angle-resolved photoemission spectroscopy experiments on three topological (Bi2)m(Bi2Se3)n superlattices: (a) Bi2Se3 (m = 0, n = 1), (b) Bi4Se3 (m = 1, n = 1), and (c) BiSe (m = 1, n = 2). Our studies have not only proven the topological nature of these materials, but also demonstrate how bulk band structure and polar chemical bonding control the surface meta's concentration, dispersion, and spin-orbital character. Case (a) is considered to provide an ideal model of the topological surface metal. Case (b) provides the three important findings: (1) the chemical identity of the surface-termination controls the orbital composition and energy distribution of the surface states, (2) there are two topological states in sequential bulk band gaps, (3) of these, one of topological state undergoes a hybridization effect that yields a momentum-dependent gap in the band structure as large as 85 meV. Case (c) has a practical significance in that the surface metal has a potentially record-breaking carrier density of ~1013cm−2 (estimated from the Fermi surface area), more than an order of magnitude higher than in Bi2Se3. This occurs as a result of charge transfer from the Bi2 layers to the Bi2Se3 layers.
Author: Eryin Wang Publisher: Springer Nature ISBN: 981151447X Category : Technology & Engineering Languages : en Pages : 90
Book Description
This book focuses on angle-resolved photoemission spectroscopy studies on novel interfacial phenomena in three typical two-dimensional material heterostructures: graphene/h-BN, twisted bilayer graphene, and topological insulator/high-temperature superconductors. Since the discovery of graphene, two-dimensional materials have proven to be quite a large “family”. As an alternative to searching for other family members with distinct properties, the combination of two-dimensional (2D) materials to construct heterostructures offers a new platform for achieving new quantum phenomena, exploring new physics, and designing new quantum devices. By stacking different 2D materials together and utilizing interfacial periodical potential and order-parameter coupling, the resulting heterostructure’s electronic properties can be tuned to achieve novel properties distinct from those of its constituent materials. This book offers a valuable reference guide for all researchers and students working in the area of condensed matter physics and materials science.
Author: Jeroen B. Oostinga Publisher: Elsevier Inc. Chapters ISBN: 0128086890 Category : Science Languages : en Pages : 48
Book Description
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.
Author: M. Zahid Hasan Publisher: Elsevier Inc. Chapters ISBN: 0128086874 Category : Science Languages : en Pages : 50
Book Description
Topological Surface States (TSS) represent new types of two dimensional electron systems with novel and unprecedented properties distinct from any quantum Hall-like or spin-Hall effects. Their topological order can be realized at room temperatures without magnetic fields and they can be turned into magnets, exotic superconductors or Kondo insulators leading to worldwide interest and activity in the topic. We review the basic concepts defining such topological matter and the key experimental probe that revealed the topological order in the bulk of these spin-orbit interaction dominated insulators. This review focuses on the key results that demonstrated the fundamental topological properties such as spin-momentum locking, non-trivial Berrys phases, mirror Chern number, absence of backscattering, protection by time-reversal and other discrete (mirror) symmetries and their remarkable persistence up to the room temperature elaborating on results first discussed by M.Z. Hasan and C.L. Kane in the Rev. of Mod. Phys., 82, 3045 (2010). Additionally, key results on broken symmetry phases such as quantum magnetism and uperconductivity induced in topological materials are briefly discussed.
Author: Christian Pauly Publisher: Springer ISBN: 3658118113 Category : Science Languages : en Pages : 172
Book Description
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.
Author: Ke He Publisher: Elsevier Inc. Chapters ISBN: 0128086904 Category : Science Languages : en Pages : 36
Book Description
Material is a key to the experimental observation of novel quantum phenomena predicted in topological insulators. In this chapter, we review the recent theoretic and experimental efforts devoted to improving the existing topological insulator materials and exploring new topological insulators. The emphasis is on growth and engineering of the properties of topological insulator thin films by molecular beam epitaxy for realization of various quantum effects.
Author: Publisher: Elsevier ISBN: 0444633189 Category : Science Languages : en Pages : 349
Book Description
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
Author: Huixia Luo Publisher: John Wiley & Sons ISBN: 1119407338 Category : Technology & Engineering Languages : en Pages : 416
Book Description
This book 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 researchers and graduate students preparing to work in this area, and it will be an essential reference both within and outside the classroom. The book begins with the fundamental description on the topological phases of matter such as one, two- and three-dimensional topological insulators, and methods and tools for topological material's investigations, topological insulators for advanced optoelectronic devices, topological superconductors, saturable absorber and in plasmonic devices. Advanced Topological Insulators provides researchers and graduate students with the physical understanding and mathematical tools needed to embark on research in this rapidly evolving field.
Author: Andrew Patton Weber
Author: Andrew Patton Weber
Author: 莊霈于
Author: Eryin Wang
Author: Jeroen B. Oostinga
Author: Yuqi Xia
Author: M. Zahid Hasan
Author: Christian Pauly
Author: Ke He
Author: 
Author: Huixia Luo