Materials and Physical Properties of Topological Insulator Bi2Te3 Thin Films by Molecular Beam Epitaxy PDF Download

Author: 林柏皓
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Author: Shuang Li
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Book Description
Searching for energy dissipation-less systems has become increasingly important for low power electronic devices. Topological insulators, a new topological state of quantum matter, have recently been proposed as an emerging material for use in low power electronics, because of the unique transport along its topologically protected edge/surface states. In addition, it has been predicted that the incorporation of magnetic elements into topological insulators could lead to the quantum anomalous Hall state, which is a truly dissipation-less system. However, the material quality of topological insulator thin films remains as a major stumbling block for exploring the novel physics of topological insulators and their proposed applications. In the first part of this thesis, I will first describe an advanced thin film deposition technique, molecular beam epitaxy (MBE) and the mini-MBE system we designed and built for topological insulator thin film growth. Then I will briefly illustrate some basic principles and sample preparation methods for a variety of characterization techniques we used for the material property investigation. In the second part of this thesis, I will present the growth and characterization of topological insulator bismuth telluride thin films grown by a two-step MBE process developed as part of this research. By optimizing the growth recipe and particularly developing the two-step growth method, defect densities were significantly reduced and higher crystal and surface quality bismuth telluride thin films were achieved. The existence of a topological surface state on our bismuth telluride thin films was also confirmed. The Fermi level of our bismuth telluride thin film was tuned to very close to the bulk gap region. The successful growth of centimeter-sized, uniform, high quality topological insulator thin films provides an excellent platform for both fundamental studies of the properties of topological insulators and fabrications of mesoscopic devices. Finally, I will report on the first successful growth of gadolinium substituted bismuth telluride thin films with high Gd concentrations by MBE. We systematically investigated the crystal structure, band structure, magnetic, and electronic properties of gadolinium substituted bismuth telluride thin films. The topological surface state was found to remain intact by Gd substitution into bismuth telluride. Although ferromagnetic behavior in gadolinium substituted bismuth telluride thin films was not observed above 2K by both magnetic and magneto-transport measurements, gadolinium substituted bismuth telluride thin films were found to have a Curie susceptibility due to the paramagnetic Gd ions with an atomic magnetic moment of 6.93 Bohr magneton per Gd ion, which suggests that it is possible to realize dissipation-less transport with a small external magnetic field or with a ferromagnetic layer on top of gadolinium substituted bismuth telluride thin films.

Author: Ke He
Publisher: Elsevier Inc. Chapters
ISBN: 0128086904
Category : Science
Languages : en
Pages : 36

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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: Li Zhang
Publisher:
ISBN:
Category :
Languages : en
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Topological insulators are a special category of materials that are insulating in the bulk but have robust conducting surface states. As an ideal candidate for low power electronics, spintronic and quantum computation, topological insulators have been actively studied both theoretically and experimentally in the past couple of years. To achieve high quality thin films of topological insulators and understand their properties thoroughly is a critical step towards all potential applications. In this dissertation, I will introduce methods to fabricate high quality topological insulator Bi2Se3 thin films using both pulsed laser deposition (PLD) and molecular beam epitaxy (MBE) with a radio frequency (RF) cracker cell. Using PLD, bilayers of topological insulator Bi2Se3 and insulating ferromagnet EuS were fabricated. Weak localization of the surface states was observed at the interface under the Curie temperature of EuS, as a direct evidence of the proximity effect. Using MBE with the RF cracker cell, high quality ultrathin Bi2Se3 films were successfully grown. Analysis of the magneto-resistance of those ultrathin samples measured at low temperature shows both the characteristic weak antilocalization from the surface states and the weak localization from the quantized bulk states, in good agreement with theoretical predictions. With our abilities to add various dopants during the deposition, and to deposit high quality thin films of different materials other than topological insulators, in both the MBE and PLD systems, we are excited to see the door to more interesting structures and fascinating physics opening in front of us.

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

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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.

Author: Huixia Luo
Publisher: John Wiley & Sons
ISBN: 1119407338
Category : Technology & Engineering
Languages : en
Pages : 416

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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: Grant Smith
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Topological insulators (TIs) are an exciting class of material desired for potential applications to spintronics and low-power electronics. The bismuth chalcogenides are canonical examples materials that exhibit these properties. These materials are often synthesized as thin films using molecular beam epitaxy (MBE) thin film deposition. This technique, while powerful, is limited by issues of substrate compatibility, wherein the interfacing materials of the greatest experimental interest are not always the materials on which TI thin film grows with the highest quality or with the sharpest interface. There is, therefore, a desire to be able to grow a thin film of bismuth chalcogenides on a substrate on which they grow to a high degree of crystallinity and then transfer that film to a substrate of interest. Such a technique was described by Bansal, et al. in 2014. We have characterized the effectiveness of this technique using atomic force microscopy (AFM), x-ray diffraction (XRD), and transport studies finding that it engenders very little damage to the film and that transferred films are, for all intents and purposes, equivalent to unaltered MBE-grown films.We explore applications of this technique to TIs interfaced with the ferrimagnet yttrium iron garnet (YIG) in order to explore coupling between the magnetization of the YIG and the unique spin states on the surface of the TI. We also utilize this substrate transfer technique for simplified plan view transmission electron microscopy (TEM) sample preparation used for the characterization of our MBE process.

Author: Inamuddin
Publisher: Materials Research Forum LLC
ISBN: 1644902850
Category : Technology & Engineering
Languages : en
Pages : 195

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Book Description
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.

Author: Jiajun Zhu
Publisher: Anchor Academic Publishing
ISBN: 3960671601
Category : Science
Languages : en
Pages : 91

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Topological insulator is one of the hottest research topics in solid state physics. This is the first book to describe the vibrational spectroscopies and electrical transport of topological insulator Bi2Se3, one of the most exciting areas of research in condensed matter physics. In particular, attempts have been made to summarize and develop the various theories and new experimental techniques developed over years from the studies of Raman scattering, infrared spectroscopy and electrical transport of topological insulator Bi2Se3. It is intended for material and physics researchers and graduate students doing research in the field of optical and electrical properties of topological insulators, providing them the physical understanding and mathematical tools needed to engage research in this quickly growing field. Some key topics in the emerging field of topological insulators are introduced.

Author: Qiliang Li
Publisher: MDPI
ISBN: 3039212257
Category : Technology & Engineering
Languages : en
Pages : 242

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Book Description
As CMOS scaling is approaching the fundamental physical limits, a wide range of new nanoelectronic materials and devices have been proposed and explored to extend and/or replace the current electronic devices and circuits so as to maintain progress with respect to speed and integration density. The major limitations, including low carrier mobility, degraded subthreshold slope, and heat dissipation, have become more challenging to address as the size of silicon-based metal oxide semiconductor field effect transistors (MOSFETs) has decreased to nanometers, while device integration density has increased. This book aims to present technical approaches that address the need for new nanoelectronic materials and devices. The focus is on new concepts and knowledge in nanoscience and nanotechnology for applications in logic, memory, sensors, photonics, and renewable energy. This research on nanoelectronic materials and devices will be instructive in finding solutions to address the challenges of current electronics in switching speed, power consumption, and heat dissipation and will be of great interest to academic society and the industry.