Quantum Transport Study in 3D Topological Insulators Nanostructures

Quantum Transport Study in 3D Topological Insulators Nanostructures PDF Author: Louis Veyrat
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

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Quantum Transport Study in 3D Topological Insulators Nanostructures

Quantum Transport Study in 3D Topological Insulators Nanostructures PDF Author: Louis Veyrat
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

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Topological Insulators

Topological Insulators PDF Author: Jeroen B. Oostinga
Publisher: Elsevier Inc. Chapters
ISBN: 0128086890
Category : Science
Languages : en
Pages : 48

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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.

Topological Insulators

Topological Insulators PDF Author: Gregory Tkachov
Publisher: CRC Press
ISBN: 9814613266
Category : Science
Languages : en
Pages : 180

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Book Description
This book is the result of dynamic developments that have occurred in condensed matter physics after the recent discovery of a new class of electronic materials: 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 car

Quantum Transport in HgTe Topological Insulator Nanostructures

Quantum Transport in HgTe Topological Insulator Nanostructures PDF Author: Johannes Ziegler
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

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Topological Insulators

Topological Insulators PDF Author: Frank Ortmann
Publisher: John Wiley & Sons
ISBN: 3527681604
Category : Technology & Engineering
Languages : en
Pages : 434

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Book Description
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.

Quantum Transport in 2 and 3 Dimensional Topological Insulators

Quantum Transport in 2 and 3 Dimensional Topological Insulators PDF Author: Di Xiao
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Book Description
Topological insulators are materials that are insulating in the bulk but that conduct via topologically protected states on the boundary. The concept of topology in condensed matter physics was first introduced to explain the integer quantum Hall (IQH) effect. The perfect quantization of these topologically protected edge states, insensitive to sample geometry and disorder, stimulated an extensive search for many exciting new topological materials. One of the milestones along the journey was the theoretical prediction and experimental discovery of Z2 topological insulators.The first class of Z2 topological insulators discovered was the 2-dimensional topological insulator (2D TI), also known as the quantum spin Hall (QSH) insulator. The 2D TI can be viewed as a variation of the IQH system but with time-reversal-symmetry (TRS). The topological invariant for a 2D TI is the Z2 number, defined by its nontrivial band structure instead of the Chern number in the IQH case. Generalizing this idea to 3 dimensions led to the discovery of the 3D TI with four Z2 invariants. Both the 2D and 3D TIs are of interest as model platforms for testing theoretical problems of fundamental interest. For instance, they allow us to realize artificial condensed matter analogs of fundamental particles such as Majorana fermions and axions that have yet to be observed in nature. They are also of interest for potential technological applications, principally spintronics and quantum computing.This dissertation focuses on the synthesis, characterization, and transport properties of both 2D and 3D TIs. We first discuss the 2D TI candidate material system, type II InAs/GaSb quantum wells, which exhibits a rich topological phase diagram that can be tuned by several parameters such as sample geometry or electrostatic gating. By changing the thicknesses of relevant layers, we are able to enter a new insulating regime where unexpected high-density quantum oscillations are observed. We elucidate this phenomenon through theoretical calculation and through control experiments. The seemingly controversial coexistence of high density states and the insulating regime can be explained by the effect of the attractive Coulomb interaction, which was not considered in earlier theories.The second topic we address is quantum transport in 3D TI systems. Breaking the TRS of the 3D TI surface states leads to many exotic phenomena, including the quantum anomalous Hall (QAH) effect and the axion insulator state. By constructing a sandwich heterostructure that has different magnetic coercive fields in the top and bottom magnetic layers, while keeping the center layer free from magnetic impurities, both the QAH and the axion insulator state can be observed in low-temperature transport measurements, when the magnetization alignment of the top and bottom layers is parallel and antiparallel, respectively. We also discuss the scaling behavior of the topological quantum phase transition between these two states.

Spin-Helical Dirac Fermions in 3D Topological Insulator Quantum Wires

Spin-Helical Dirac Fermions in 3D Topological Insulator Quantum Wires PDF Author: Romain Giraud
Publisher:
ISBN:
Category : Science
Languages : en
Pages :

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Book Description
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.

Topological Insulators

Topological Insulators PDF Author: Frank Ortmann
Publisher: John Wiley & Sons
ISBN: 3527681582
Category : Technology & Engineering
Languages : en
Pages : 432

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Book Description
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.

Topological Insulators

Topological Insulators PDF Author: Joel E. Moore
Publisher: Elsevier Inc. Chapters
ISBN: 0128086831
Category : Science
Languages : en
Pages : 31

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Book Description
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.

Heterojunctions and Nanostructures

Heterojunctions and Nanostructures PDF Author: Vasilios N. Stavrou
Publisher: BoD – Books on Demand
ISBN: 1789234689
Category : Science
Languages : en
Pages : 130

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Book Description
The current book entitled Heterojunctions and Nanostructures is divided into two sections. In Section 1, the chapters are related to topological insulators where their theoretical aspects, their current experiments, and their applications are presented. A few presented topics are, among others, the topological phases of matter, band topology of insulators and also of Weyl semimetals, transport properties of 3D topological insulator quantum wires and the influence of disorder, transport properties of quasi-1D (and 2D) topological surface states, quantum coherence, and topological insulator thin-film Hall bar device. In Section 2, the chapters are related to light devices such as laser diodes and their fabrication techniques. This section includes, among others, topics such as semiconductor quantum nanowire laser diodes, solutions of Schrodinger equation in nanostructures, numerical methods, light-to-electricity conversion devices, photoexcited carrier transportation process in quantum wells and quantum dots, growth mode and characterization of heterostructure of large lattice mismatch, and photoionization cross section.