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Fabrication And Electrical Properties Of Topological Insulator Thin Films
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Book Synopsis Fabrication and Electrical Properties of Topological Insulator Thin Films by : Li Zhang
Download or read book Fabrication and Electrical Properties of Topological Insulator Thin Films written by Li Zhang and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Book Synopsis Transport Studies of the Electrical, Magnetic and Thermoelectric properties of Topological Insulator Thin Films by : Jinsong Zhang
Download or read book Transport Studies of the Electrical, Magnetic and Thermoelectric properties of Topological Insulator Thin Films written by Jinsong Zhang and published by Springer. This book was released on 2016-04-18 with total page 128 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents the transport studies of topological insulator thin films grown by molecular beam epitaxy. Through band structure engineering, the ideal topological insulators, (Bi1−xSbx)2Te3 ternary alloys, are successfully fabricated, which possess truly insulating bulk and tunable conducting surface states. Further transport measurements on these ternary alloys reveal a disentanglement between the magnetoelectric and thermoelectric properties. In magnetically doped topological insulators, the fascinating quantum anomalous Hall effect was experimentally observed for the first time. Moreover, the topology-driven magnetic quantum phase transition was Systematically controlled by varying the strength of the spin-orbital coupling. Readers will not only benefit from the description of the technique of transport measurements, but will also be inspired by the understanding of topological insulators.
Book Synopsis Topological Insulator and Magnetically Doped Topological Insulator Thin Films by Molecular Beam Epitaxy by : Shuang Li
Download or read book Topological Insulator and Magnetically Doped Topological Insulator Thin Films by Molecular Beam Epitaxy written by Shuang Li and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Book Synopsis Optical and electrical properties of topological insulator Bi2Se3 by : Jiajun Zhu
Download or read book Optical and electrical properties of topological insulator Bi2Se3 written by Jiajun Zhu and published by diplom.de. This book was released on 2017-07-12 with total page 88 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Book Synopsis Binary and Rare Earth-doped Topological Insulator Thin Films by : Sara Elizabeth Harrison
Download or read book Binary and Rare Earth-doped Topological Insulator Thin Films written by Sara Elizabeth Harrison and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Topological insulators (TIs) are a newly discovered class of electronic materials which are characterized by an insulating bulk band gap and metallic conducting edge/surface states. Their novel electronic band structure arises from strong spin-orbit coupling that leads to bulk energy band inversion which necessitates the formation of metallic states at their physical boundaries with dissimilar materials. These metallic edge/surface states have intriguing spin-momentum locking properties and a very robust nature, due to scattering protection by time-reversal symmetry (TRS), which make them interesting from both a fundamental science perspective as well as for their potential use in future generation electronic and spintronic applications. Recently, the discovery of the three-dimensional (3D) TIs in the bismuth telluride family of materials has provided an exciting new direction for TI research. The surface states on these 3D TIs are detectable at room temperature which eases the harsh requirements previously needed to study TIs and increases their potential for use in practical applications. As commercially successful thermoelectric materials, the use of widely accessible bulk crystals of the bismuth telluride family of 3D TIs has enabled early studies of their topological surface states. However, a prerequisite for realizing many proposed TI applications is the synthesis of high crystalline quality thin films which necessitates efforts in thin film materials engineering. In addition, a new area of TI materials research has also recently emerged around breaking the TRS in 3D TIs by inducing ferromagnetism through magnetic doping. This approach is predicted to provide a promising route for realizing exotic physical states, such as the recently discovered quantum anomalous Hall state. However, exploring magnetically induced phenomena has been experimentally challenging which has prompted the search for alternative TI systems through fundamental magnetic doping studies. This dissertation focuses on the growth and characterization of binary and rare earth-doped bismuth telluride thin films. All samples were fabricated using molecular beam epitaxy (MBE) and their structural, electronic, and magnetic properties were characterized using a comprehensive set of surface- and bulk-sensitive analytical techniques. The development of a new two-temperature step MBE growth process for bismuth telluride thin films is presented. The two-step method is shown to yield films of high crystallinity with significantly improved material properties over films grown using other growth recipes. This growth technique served as the starting platform for other studies presented in this work, including investigations into surface preparation techniques for ex situ grown TI thin films and magnetic doping studies with rare earth elements. Major shortcomings of conventional preparation techniques for preserving or restoring the surface of air exposed TI films are also presented. Commonly employed sputter cleaning is shown to be incompatible with TI samples that are prone to severe oxidation such as magnetically doped TIs. Se- and Te-capping layer studies provide new evidence that this commonly employed technique is ineffective at preserving the as-grown properties of bismuth telluride thin films. Alternatively, the efficacy of in situ cleaving for preparation of clean binary and rare earth-doped TI surfaces is demonstrated. Finally, the first experimental work on MBE-grown Dy-doped bismuth telluride thin films is presented. X-ray studies reveal that large concentrations of Dy, ranging from 0% to 35.5% (in % of the Bi sites), can be incorporated into the host bismuth telluride crystal lattice without the formation of secondary phases. A subset of films in the doping series are shown to maintain a high degree of crystallinity with evidence for substitutional doping of Dy and the absence of intercalation in the van der Waals gaps. Electronic band structure measurements show that there is a critical Dy doping concentration above which evidence for a sizable gap (tens of meV) in the surface state is detected. Bulk magnetometry reveals paramagnetic behavior down to low temperatures for all samples in the doping series. The use of rare earth dopants introduces the highest magnetic moments into a TI system, which could have a transformative potential for TI-based applications in the future.
Book Synopsis Epitaxial Engineering of High Quality Topological Insulator Films by : Nikesh Koirala
Download or read book Epitaxial Engineering of High Quality Topological Insulator Films written by Nikesh Koirala and published by . This book was released on 2016 with total page 93 pages. Available in PDF, EPUB and Kindle. Book excerpt: Topological insulator is an exciting phase of matter because at its boundaries reside table-top version of Dirac fermions, while its bulk is supposed to be insulating. However, in real materials this latter condition is often far from being fulfilled and the bulk of the material is usually highly conducting due to the presence of inevitable defects. The aim of this dissertation is to understand the role of these defects on electrical properties of chalcogenide based topological insulators and utilize this knowledge to fabricate high quality films. Topological insulator is an exciting phase of matter because at its boundaries reside table-top version of Dirac fermions, while its bulk is supposed to be insulating. However, in real materials this latter condition is often far from being fulfilled and the bulk of the material is usually highly conducting due to the presence of inevitable defects. The aim of this dissertation is to understand the role of these defects on electrical properties of chalcogenide based topological insulators and utilize this knowledge to fabricate high quality films. We start out by briefly introducing topological insulators. This is followed by Chapter 2, where we discuss experimental techniques that are pertinent to this work: thin film growth technique and electrical measurement. In Chapter 3, we will first seek theoretical understanding of role of defects in determining electrical properties of topological insulators and follow this by experimental results on Bi2Se3 films grown on epitaxially engineered virtual substrate, which show near ideal topological insulator behavior: namely, high mobility conduction through topological surface states and highly insulating bulk. We follow this in Chapter 4 with report of topological surface state originated quantum Hall effect in these films. A summary of results followed by future outlook will conclude the dissertation.
Book Synopsis Optical Properties of Bismuth-Based Topological Insulators by : Paola Di Pietro
Download or read book Optical Properties of Bismuth-Based Topological Insulators written by Paola Di Pietro and published by Springer Science & Business Media. This book was released on 2013-10-24 with total page 129 pages. Available in PDF, EPUB and Kindle. Book excerpt: Topological Insulators (TIs) are insulators in the bulk, but have exotic metallic states at their surfaces. The topology, associated with the electronic wavefunctions of these systems, changes when passing from the bulk to the surface. This work studies, by means of infrared spectroscopy, the low energy optical conductivity of Bismuth based TIs in order to identify the extrinsic charge contribution of the bulk and to separate it from the intrinsic contribution of the surface state carriers. The extensive results presented in this thesis definitely shows the 2D character of the carriers in Bismuth-based topological insulators. The experimental apparatus and the FTIR technique, the theory of optical properties and Surface Plasmon Polaritons, as well as sample preparation of both crystals and thin films, and the analysis procedures are thoroughly described.
Book Synopsis Topological Insulators by : Inamuddin
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 Insulators written by Ke He and published by Elsevier Inc. Chapters. This book was released on 2013-11-23 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Book Synopsis Polarization Dependent Photocurrents in Thin Films of the Topological Insulator Bi2Se3 by : Claudia M. Lau
Download or read book Polarization Dependent Photocurrents in Thin Films of the Topological Insulator Bi2Se3 written by Claudia M. Lau and published by . This book was released on 2012 with total page 68 pages. Available in PDF, EPUB and Kindle. Book excerpt: Topological insulators are a new class of three-dimensional quantum materials whose interior or bulk is an insulator but whose surface is a conductor. Bi2Se3 is a prototypical topological insulator that physicists at MIT are manufacturing and studying. Various interesting properties of the topological insulator include the flow of pure spin currents and topological protection. Pure spin current, distinct from electric current, is a net flow of spin without a net flow of charge. Recent research at MIT has revealed that shining circularly polarized laser light on a topological insulator turns its surface's pure spin current into a spin-polarized electrical current. The band structure of the bulk of a topological insulator resembles that of an ordinary insulator; the conduction band and valence band are separated, with the Fermi level falling between them. However, for Bi2Se3, the conducting surface's dispersion relation can be modeled by a Dirac cone, which crosses the Fermi level. Electrons with opposing spins reside on opposite sides of the Dirac cone. Illuminating a topological insulator with either left or right circularly polarized light depopulates one side of the Dirac cone, leaving on the other side the desired spin-polarized electrical current. In the experiment performed for this thesis, thin films of Bi2Se3 were grown on substrates of sapphire via molecular beam epitaxy (MBE). Electrical devices on a micron scale were then fabricated on the thin film surface and used to measure surface currents. Steps of this experiment included characterizing the surface quality of a sapphire substrate using atomic force microscopy (AFM), making electrical devices with Bi2Se3 via the processes of optical lithography, ion milling, and electron beam metal deposition. Photocurrents across these electrical devices were induced by the manipulation of optics and lasers and measured using low noise electronics. Experimental results revealed that it was indeed possible to induce spin-polarized electrical currents on thin films of MBE grown Bi2Se3. The desired photocurrent was observed when the laser beam spot size was enlargened to illuminate the entirety of the Bi2Se3 device simultaneously. These results were not replicable when the laser was more tightly focused onto a smaller area. Scanning the focused laser beam across the Bi2Se3 confirmed that different photocurrents were being induced at different points; these results led us to the conclude that there was something inhomogenous about our device. The reason behind this device inhomogeneity is still under investigation.
Book Synopsis The Fabrication, Microstructure and Electrical Properties of Thallium-based High Temperature Superconductor Thin Films by : John D. O'Connor
Download or read book The Fabrication, Microstructure and Electrical Properties of Thallium-based High Temperature Superconductor Thin Films written by John D. O'Connor and published by . This book was released on 1997 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Applications of Laser Ablation by : Dongfang Yang
Download or read book Applications of Laser Ablation written by Dongfang Yang and published by BoD – Books on Demand. This book was released on 2016-12-21 with total page 430 pages. Available in PDF, EPUB and Kindle. Book excerpt: Laser ablation refers to the phenomenon in which a low wavelength and short pulse (ns-fs) duration of laser beam irradiates the surface of a target to induce instant local vaporization of the target material generating a plasma plume consisting of photons, electrons, ions, atoms, molecules, clusters, and liquid or solid particles. This book covers various aspects of using laser ablation phenomenon for material processing including laser ablation applied for the deposition of thin films, for the synthesis of nanomaterials, and for the chemical compositional analysis and surface modification of materials. Through the 18 chapters written by experts from international scientific community, the reader will have access to the most recent research and development findings on laser ablation through original research studies and literature reviews.
Book Synopsis Advanced Topological Insulators by : Huixia Luo
Download or read book Advanced Topological Insulators written by Huixia Luo and published by John Wiley & Sons. This book was released on 2019-03-12 with total page 400 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Book Synopsis Thermoelectric Thin Films by : Paolo Mele
Download or read book Thermoelectric Thin Films written by Paolo Mele and published by Springer. This book was released on 2019-07-17 with total page 211 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book will provide readers with deep insight into the intriguing science of thermoelectric thin films. It serves as a fundamental information source on the techniques and methodologies involved in thermoelectric thin film growth, characterization and device processing. This book involves widespread contributions on several categories of thermoelectric thin films: oxides, chalcogenides, iodates, nitrides and polymers. This will serve as an invaluable resource for experts to consolidate their knowledge and will provide insight and inspiration to beginners wishing to learn about thermoelectric thin films. Provides a single-source reference on a wide spectrum of topics related to thermoelectric thin films, from organic chemistry to devices, from physical chemistry to applied physics, from synthesis to device implementation; Covers several categories of thermoelectric thin films based on different material approaches such as oxides, chalcogenides, iodates, nitrides and polymers; Discusses synthesis, characterization, and device processing of thermoelectric thin films, as well as the nanoengineering approach to tailor the properties of the used materials at the nanoscale level.
Book Synopsis Topological Insulators by : Inamuddin
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.
Author :Satishchandra B. Ogale Publisher :Springer Science & Business Media ISBN 13 :9780387258027 Total Pages :440 pages Book Rating :4.2/5 (58 download)
Book Synopsis Thin Films and Heterostructures for Oxide Electronics by : Satishchandra B. Ogale
Download or read book Thin Films and Heterostructures for Oxide Electronics written by Satishchandra B. Ogale and published by Springer Science & Business Media. This book was released on 2005-07-15 with total page 440 pages. Available in PDF, EPUB and Kindle. Book excerpt: Oxides form a broad subject area of research and technology development which encompasses different disciplines such as materials science, solid state chemistry, physics etc. The aim of this book is to demonstrate the interplay of these fields and to provide an introduction to the techniques and methodologies involving film growth, characterization and device processing. The literature in this field is thus fairly scattered in different research journals covering one or the other aspect of the specific activity. This situation calls for a book that will consolidate this information and thus enable a beginner as well as an expert to get an overall perspective of the field, its foundations, and its projected progress.
Book Synopsis Emergent Transport Properties of Magnetic Topological Insulator Heterostructures by : Kenji Yasuda
Download or read book Emergent Transport Properties of Magnetic Topological Insulator Heterostructures written by Kenji Yasuda and published by Springer Nature. This book was released on 2020-09-07 with total page 109 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book reveals unique transport phenomena and functionalities in topological insulators coupled with magnetism and superconductivity. Topological insulators are a recently discovered class of materials that possess a spin-momentum-locked surface state. Their exotic spin texture makes them an exciting platform for investigating emergent phenomena, especially when coupled with magnetism or superconductivity. Focusing on the strong correlation between electricity and magnetism in magnetic topological insulators, the author presents original findings on current-direction-dependent nonreciprocal resistance, current-induced magnetization reversal and chiral edge conduction at the domain wall. In addition, he demonstrates how the coupling between superconductivity and topological surface state leads to substantial nonreciprocal resistance. The author also elucidates the origins of these phenomena and deepens readers’ understanding of the topologically nontrivial electronic state. The book includes several works which are published in top journals and were selected for the President’s Award by the University of Tokyo and for the Ikushi Prize, awarded to distinguished Ph.D. students in Japan.
