Download or read book Dynamics of electrons in 2D materials written by Sami Siraj-Dine and published by . This book was released on 2020 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Au cours de cette thèse, nous avons proposé des méthodes théoriques et numériques pour étudier le comportement des électrons dans les matériaux périodiques, avec un intérêt particulier pour les matériaux 2D, comme le graphène, et les isolants topologiques. La thèse se compose de trois parties, organisées comme suit. La première partie fournit un algorithme simple et doté d'une preuve mathématique pour construire des fonctions Wannier localisées, avec pour seule condition que le système ait des nombres de Chern triviaux. Sur la base d'une preuve explicite et constructive des homotopies pour le groupe unitaire, l'algorithme permet de construire des Wannier localisés pour des isolateurs topologiques tels que le modèle Kane-Mele. La méthode est validée par des tests numériques pour plusieurs systèmes. Dans la deuxième partie, nous proposons une méthode d'approximation des fonctions de Wannier adaptée au calcul des Hamiltoniens de tight-binding dans les hétérostructures de van der Waals non périodiques, c'est-à-dire des couches de matériaux 2D empilées les unes sur les autres, liées entre elles par des forces de van der Waals relativement faibles. Ce cadre n'est pas adapté pour les outils de calcul habituels de la physique des solides, qui reposent sur la périodicité des cristaux. Dans ce contexte, une approximation du premier ordre consiste à considérer les fonctions de Wannier calculées sur chaque couche indépendamment. Nous proposons donc un schéma d'approximation pour les fonctions de Wannier qui permet un calcul efficace des coefficients de matrice tight-binding, même dans le cas non périodique. La troisième partie est théorique et consacrée à l'étude des électrons indépendants à l'état fondamental dans un cristal périodique, mis en mouvement par un champ électrique uniforme à l'instant initial. Nous définissons rigoureusement le courant par unité de volume et étudions ses propriétés en utilisant à la fois la réponse linéaire et la théorie adiabatique. Nos résultats fournissent un cadre unifié pour divers phénomènes tels que la quantification de la conductivité de Hall des isolants topologiques, le régime balistique des électrons dans les métaux, les oscillations de Bloch dans la réponse en temps long des métaux et la conductivité statique du graphène.
Download or read book Optics Light and Lasers written by Dieter Meschede and published by John Wiley & Sons. This book was released on 2017-06-06 with total page 563 pages. Available in PDF, EPUB and Kindle. Book excerpt: Dieses Buch ist genau richtig für Einsteiger in das Fachgebiet. Schwierige Effekte werden direkt und leicht verständlich präsentiert. Diese aktualisierte, erweiterte Auflage bietet neue Kapitel zu neuen Themen wie Plasmonik, Frequenzkämme auf Femto-Ebene und Quantenkaskadenlaser
Download or read book 2D Monoelemental Materials Xenes and Related Technologies written by Zongyu Huang and published by CRC Press. This book was released on 2022-04-19 with total page 166 pages. Available in PDF, EPUB and Kindle. Book excerpt: Monoelemental 2D materials called Xenes have a graphene-like structure, intra-layer covalent bond, and weak van der Waals forces between layers. Materials composed of different groups of elements have different structures and rich properties, making Xenes materials a potential candidate for the next generation of 2D materials. 2D Monoelemental Materials (Xenes) and Related Technologies: Beyond Graphene describes the structure, properties, and applications of Xenes by classification and section. The first section covers the structure and classification of single-element 2D materials, according to the different main groups of monoelemental materials of different components and includes the properties and applications with detailed description. The second section discusses the structure, properties, and applications of advanced 2D Xenes materials, which are composed of heterogeneous structures, produced by defects, and regulated by the field. Features include: Systematically detailed single element materials according to the main groups of the constituent elements Classification of the most effective and widely studied 2D Xenes materials Expounding upon changes in properties and improvements in applications by different regulation mechanisms Discussion of the significance of 2D single-element materials where structural characteristics are closely combined with different preparation methods and the relevant theoretical properties complement each other with practical applications Aimed at researchers and advanced students in materials science and engineering, this book offers a broad view of current knowledge in the emerging and promising field of 2D monoelemental materials.
Download or read book Valleytronics In 2d Materials written by Kuan Eng Johnson Goh and published by World Scientific. This book was released on 2023-06-26 with total page 360 pages. Available in PDF, EPUB and Kindle. Book excerpt: Driven by the advent of two-dimensional materials, valleytronics is emerging as the next hot field of research in materials science. While the use of charge or spin degrees of freedom in electronic materials as information carriers is familiar and well-appreciated, employment of the valley degree of freedom as an information carrier has remained elusive for many decades. Shortly following the discovery of isolated graphene, 2D semiconductors such as transition metal dichalcogenides were also isolated and investigated. We now understand that these materials can have separately addressable valleys because each valley can be uniquely coupled to a spin state. This imparts the ability to address different valleys (like pseudospins) with electric field, magnetic field, or light, and there is now a real possibility to engineer practical devices based on using valley as the information carrier.Valleytronics in 2D Materials is the first book in the world on the topic of valleytronics. The reader is introduced to the concept via a brief history emphasizing the challenges that impeded its development for so long. We then dive into the valley physics of 2D semiconductors to explain the recent excitement in 2D valleytronics, the scientific investigations to confirm the addressable valleys, and the attempts to engineer valley devices for practical purposes. The text takes on a decidedly practical approach towards the subject, seeking to bring the reader quickly into the field by presenting the minimum theoretical basis for understanding the use of the valley degree of freedom in devices. A selection of key works establishing the scientific underpinnings of valley addressability and control are described to help the reader grasp the current stage of understanding, the technical foundations established, and the open questions. The renewal in valleytronics is yet unfinished, but with more than a decade of research and engineering efforts devoted in recent times, this book seeks to provide a timely reference for students, scientists and engineers to join this exciting journey and perhaps help to create the next disruption in information technology.
Download or read book Spin Dynamics in Two Dimensional Quantum Materials written by Marc Vila Tusell and published by Springer Nature. This book was released on 2021-11-10 with total page 169 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis focuses on the exploration of nontrivial spin dynamics in graphene-based devices and topological materials, using realistic theoretical models and state-of-the-art quantum transport methodologies. The main outcomes of this work are: (i) the analysis of the crossover from diffusive to ballistic spin transport regimes in ultraclean graphene nonlocal devices, and (ii) investigation of spin transport and spin dynamics phenomena (such as the (quantum) spin Hall effect) in novel topological materials, such as monolayer Weyl semimetals WeTe2 and MoTe2. Indeed, the ballistic spin transport results are key for further interpretation of ultraclean spintronic devices, and will enable extracting precise values of spin diffusion lengths in diffusive transport and guide experiments in the (quasi)ballistic regime. Furthermore, the thesis provides an in-depth theoretical interpretation of puzzling huge measured efficiencies of the spin Hall effect in MoTe2, as well as a prediction of a novel canted quantum spin Hall effect in WTe2 with spins pointing in the yz plane.
Download or read book Two Dimensional Materials for Nonlinear Optics written by Qiang Wang and published by John Wiley & Sons. This book was released on 2024-01-03 with total page 373 pages. Available in PDF, EPUB and Kindle. Book excerpt: Comprehensive resource covering concepts, perspectives, and skills required to understand the preparation, nonlinear optics, and applications of two-dimensional (2D) materials Bringing together many interdisciplinary experts in the field of 2D materials with their applications in nonlinear optics, Two-Dimensional Materials for Nonlinear Optics covers preparation methods for various novel 2D materials, such as transition metal dichalcogenides (TMDs) and single elemental 2D materials, excited-state dynamics of 2D materials behind their outstanding performance in photonic devices, instrumentation for exploring the photoinduced excited-state dynamics of the 2D materials spanning a wide time scale from ultrafast to slow, and future trends of 2D materials on a series of issues like fabrications, dynamic investigations, and photonic/optoelectronic applications. Powerful nonlinear optical characterization techniques, such as Z-scan measurement, femtosecond transient absorption spectroscopy, and microscopy are also introduced. Edited by two highly qualified academics with extensive experience in the field, Two-Dimensional Materials for Nonlinear Optics covers sample topics such as: Foundational knowledge on nonlinear optical properties, and fundamentals and preparation methods of 2D materials with nonlinear optical properties Modulation and enhancement of optical nonlinearity in 2D materials, and nonlinear optical characterization techniques for 2D materials and their applications in a specific field Novel nonlinear optical imaging systems, ultrafast time-resolved spectroscopy for investigating carrier dynamics in emerging 2D materials, and transient terahertz spectroscopy 2D materials for optical limiting, saturable absorber, second and third harmonic generation, nanolasers, and space use With collective insight from researchers in many different interdisciplinary fields, Two-Dimensional Materials for Nonlinear Optics is an essential resource for materials scientists, solid state chemists and physicists, photochemists, and professionals in the semiconductor industry who are interested in understanding the state of the art in the field.
Download or read book Spintronic 2D Materials written by Wenqing Liu and published by Woodhead Publishing. This book was released on 2019-11-28 with total page 322 pages. Available in PDF, EPUB and Kindle. Book excerpt: Spintronic 2D Materials: Fundamentals and Applications provides an overview of the fundamental theory of 2D electronic systems that includes a selection of the most intensively investigated 2D materials. The book tells the story of 2D spintronics in a systematic and comprehensive way, providing the growing community of spintronics researchers with a key reference. Part One addresses the fundamental theoretical aspects of 2D materials and spin transport, while Parts Two through Four explore 2D material systems, including graphene, topological insulators, and transition metal dichalcogenides. Each section discusses properties, key issues and recent developments. In addition, the material growth method (from lab to mass production), device fabrication and characterization techniques are included throughout the book. - Discusses the fundamentals and applications of spintronics of 2D materials, such as graphene, topological insulators and transition metal dichalcogenides - Includes an in-depth look at each materials system, from material growth, device fabrication and characterization techniques - Presents the latest solutions on key challenges, such as the spin lifetime of 2D materials, spin-injection efficiency, the potential proximity effects, and much more
Download or read book 2D Materials written by Phaedon Avouris and published by Cambridge University Press. This book was released on 2017-06-29 with total page 521 pages. Available in PDF, EPUB and Kindle. Book excerpt: Learn about the most recent advances in 2D materials with this comprehensive and accessible text. Providing all the necessary materials science and physics background, leading experts discuss the fundamental properties of a wide range of 2D materials, and their potential applications in electronic, optoelectronic and photonic devices. Several important classes of materials are covered, from more established ones such as graphene, hexagonal boron nitride, and transition metal dichalcogenides, to new and emerging materials such as black phosphorus, silicene, and germanene. Readers will gain an in-depth understanding of the electronic structure and optical, thermal, mechanical, vibrational, spin and plasmonic properties of each material, as well as the different techniques that can be used for their synthesis. Presenting a unified perspective on 2D materials, this is an excellent resource for graduate students, researchers and practitioners working in nanotechnology, nanoelectronics, nanophotonics, condensed matter physics, and chemistry.
Download or read book Conductor Insulator Quantum Phase Transitions written by Vladimir Dobrosavljevic and published by Oxford University Press. This book was released on 2012-06 with total page 583 pages. Available in PDF, EPUB and Kindle. Book excerpt: When many particles come together how do they organize themselves? And what destroys this organization? Combining experiments and theory, this book describes intriguing quantum phases - metals, superconductors and insulators - and transitions between them. It captures the excitement and the controversies on topics at the forefront of research.
Download or read book Fundamentals and Sensing Applications of 2D Materials written by Chandra Sekhar Rout and published by Woodhead Publishing. This book was released on 2019-06-15 with total page 514 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fundamentals and Sensing Applications of 2D Materials provides a comprehensive understanding of a wide range of 2D materials. Examples of fundamental topics include: defect and vacancy engineering, doping and advantages of 2D materials for sensing, 2D materials and composites for sensing, and 2D materials in biosystems. A wide range of applications are addressed, such as gas sensors based on 2D materials, electrochemical glucose sensors, biosensors (enzymatic and non-enzymatic), and printed, stretchable, wearable and flexible biosensors. Due to their sub-nanometer thickness, 2D materials have a high packing density, thus making them suitable for the fabrication of thin film based sensor devices. Benefiting from their unique physical and chemical properties (e.g. strong mechanical strength, high surface area, unparalleled thermal conductivity, remarkable biocompatibility and ease of functionalization), 2D layered nanomaterials have shown great potential in designing high performance sensor devices. - Provides a comprehensive overview of 2D materials systems that are relevant to sensing, including transition metal dichalcogenides, metal oxides, graphene and other 2D materials system - Includes information on potential applications, such as flexible sensors, biosensors, optical sensors, electrochemical sensors, and more - Discusses graphene in terms of the lessons learned from this material for sensing applications and how these lessons can be applied to other 2D materials
Download or read book Theoretical Study of Charge Dynamics in Two dimensional Materials written by Yuxiang Liu and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Exfoliation of graphene in 2004 initiated intensive attention on layered two-dimensional (2D) materials. So far, except for graphene, a large family of 2D materials has been reported, such as transition metal dichalcogenides (TMDCs), hexagonal boron nitride, black phosphorene, metal nitrides/carbides and their van der Waals heterostructures, etc. The large number of species, unique electrical and optical properties and versatile functionalities render 2D materials as promising materials for electronic, optoelectronic and photovoltaic devices. This thesis investigates ultrafast charge dynamics in 2D material system based on real-time time-dependent density functional theory method within Ehrenfest framework. This work is divided into three major parts. In first part, we investigate the ultrafast interlayer charge transfer process in the graphene/WS2 heterostructure. Our results demonstrate that photo-induced holes transfer from WS2 to graphene more efficient than electrons. The ultrafast charge dynamics arises from the coupling to nuclear vibrations and its amplitude and polarity show a strong dependence on the external electric fields. Further analysis reveals that carrier dynamics in the heterostructure is the result of competition between interlayer and intralayer relaxation process, which is governed by the couplings between carriers and their acceptor states. This work establishes a firm correlation between the charge dynamics and couplings between states in 2D heterostructures, and provide practical methodology to manipulate carrier dynamics at heterointerfaces. In second part, we study the carrier multiplication (CM) phenomenon in six monolayer TMDCs MX2 (M = Mo, W; X = S, Se, Te). Our results present that CM is observed in all six TMDCs. The threshold energy of CM can be substantially reduced to 1.75 bandgap (Eg) via couplings to phonon modes. Since electron-phonon couplings can result in significant changes in electronic structures, even trigger semiconductor-metal transition, and eventually assist CM beyond threshold limit. Chalcogen vacancies can further decrease the threshold due to sub-gap defect states. In particular for WS2, CM occurs with excitation energy of only 1.51Eg. Our results identify TMDCs as attractive candidate materials for efficient photovoltaic devices with the advantages of high photo-conductivity and phonon-assisted CM characteristic. In third part, we report the effect of doping levels on CM in graphene. Our calculation results indicate that doping level can introduce remarkable differences in CM conversion efficiency in graphene. Specifically, the CM quantum yield can be promoted from 1.41 to 1.89 when the Fermi level rising from 0.40 eV to 0.78 eV via n-doping. Consistently, time- and angle-resolved photoemission spectroscopy measurements on n-doped graphene present the same correlation between doping levels and CM conversion efficiency. Our results provide a practical strategy to promote the performance of graphene as a photovoltaic material by tuning doping levels.
Download or read book Spin Current written by Sadamichi Maekawa and published by Oxford University Press. This book was released on 2017 with total page 541 pages. Available in PDF, EPUB and Kindle. Book excerpt: In a new branch of physics and technology, called spin-electronics or spintronics, the flow of electrical charge (usual current) as well as the flow of electron spin, the so-called "spin current", are manipulated and controlled together. This book is intended to provide an introduction and guide to the new physics and applications of spin current.
Download or read book Correlated Electron Phenomena in 2D Materials written by Joseph G. Lambert and published by . This book was released on 2016 with total page 268 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this thesis, I present experimental results on coherent electron phenomena in layered two-dimensional materials: single layer graphene and van der Waals coupled 2D TiSe2. Graphene is a two-dimensional single-atom thick sheet of carbon atoms first derived from bulk graphite by the mechanical exfolia- tion technique in 2004. Low-energy charge carriers in graphene behave like massless Dirac fermions, and their density can be easily tuned between electron-rich and hole-rich quasiparticles with electrostatic gating techniques. The sharp interfaces between regions of different carrier densities form barriers with selective transmission, making them behave as partially reflecting mirrors. When two of these interfaces are set at a separation distance within the phase coherence length of the carriers, they form an electronic version of a Fabry-Perot cavity. I present measurements and analysis of multiple Fabry-Perot modes in graphene with parallel electrodes spaced a few hundred nanometers apart. Transition metal dichalcogenide (TMD) TiSe2 is part of the family of materials that coined the term "materials beyond graphene". It contains van der Waals coupled trilayer stacks of Se-Ti-Se. Many TMD materials exhibit a host of interesting correlated electronic phases. In particular, TiSe2 exhibits chiral charge density waves (CDW) below TCDW ~ 200 K. Upon doping with copper, the CDW state gets suppressed with Cu concentration, and CuxTiSe2 becomes superconducting with critical temperature of Tc = 4.15 K. There is still much debate over the mechanisms governing the coexistence of the two correlated electronic phases - CDW and superconductivity. I will present some of the first conductance spectroscopy measurements of proximity coupled superconductor- CDW systems. Measurements reveal a proximity-induced critical current at the Nb-TiSe2 interfaces, suggesting pair correlations in the pure TiSe2. The results indicate that superconducting order is present concurrently with CDW in pure TiSe2, contradicting the notion of a competition between two correlated electron states.
Download or read book 2D Materials for Nanophotonics written by Young Min Jhon and published by Elsevier. This book was released on 2020-11-29 with total page 413 pages. Available in PDF, EPUB and Kindle. Book excerpt: 2D Materials for Nanophotonics presents a detailed overview of the applications of 2D materials for nanophotonics, covering the photonic properties of a range of 2D materials including graphene, 2D phosphorene and MXenes, and discussing applications in lighting and energy storage. This comprehensive reference is ideal for readers seeking a detailed and critical analysis of how 2D materials are being used for a range of photonic and optical applications. - Outlines the major photonic properties in a variety of 2D materials - Demonstrates major applications in lighting and energy storage - Explores the challenges of using 2D materials in photonics
Download or read book Two dimensional Materials written by Pramoda Kumar Nayak and published by BoD – Books on Demand. This book was released on 2016-08-31 with total page 282 pages. Available in PDF, EPUB and Kindle. Book excerpt: There are only a few discoveries and new technologies in materials science that have the potential to dramatically alter and revolutionize our material world. Discovery of two-dimensional (2D) materials, the thinnest form of materials to ever occur in nature, is one of them. After isolation of graphene from graphite in 2004, a whole other class of atomically thin materials, dominated by surface effects and showing completely unexpected and extraordinary properties, has been created. This book provides a comprehensive view and state-of-the-art knowledge about 2D materials such as graphene, hexagonal boron nitride (h-BN), transition metal dichalcogenides (TMD) and so on. It consists of 11 chapters contributed by a team of experts in this exciting field and provides latest synthesis techniques of 2D materials, characterization and their potential applications in energy conservation, electronics, optoelectronics and biotechnology.
Download or read book The Physics of the Two Dimensional Electron Gas written by J.T. Devreese and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 444 pages. Available in PDF, EPUB and Kindle. Book excerpt: The 1986 Advanced Study Institute on "The Physics of the two-Dimen sional Electron Gas" took place at the Conference Centre liTer Helme", close to Oostende (Belgium), from June 2 till 16, 1986. We were motivated to organize this Advanced Study Institute in view of the recent experimental and theoretical progress in the study of the two-dimensional electron gas. An additional motivation was our own theore tical interest in cyclotron resonance in two-dimensional electron systems at our institute. It is my pleasure to thank several instances and people who made this Advanced Study Institute possible. First of all, the sponsor of the Advanced Study Institute, the NATO Scientific Committee. Furthermore, the co sponsors: Agfa Gevaert, Bell Telephone Mfg. Co. N.V., Burroughs Belgium. Control Data. Digital Equipment Corporation, Esso Belgium. European Research Office (USA). Kredietbank. National Science Foundation (USA). Special thanks are due to the members of the Program Committee and the members of the Organizing Committee. I would also like to thank Mrs. H. Evans for typing assistance.
Download or read book Advanced 2D Materials written by Ashutosh Tiwari and published by John Wiley & Sons. This book was released on 2016-06-22 with total page 544 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book brings together innovative methodologies and strategies adopted in the research and developments of Advanced 2D Materials. Well-known worldwide researchers deliberate subjects on (1) Synthesis, characterizations, modeling and properties, (2) State-of-the-art design and (3) innovative uses of 2D materials including: Two-dimensional layered gallium selenide Synthesis of 2D boron nitride nanosheets The effects of substrates on 2-D crystals Electrical conductivity and reflectivity of models of some 2D materials Graphene derivatives in semicrystalline polymer composites Graphene oxide based multifunctional composites Covalent and non-covalent polymer grafting of graphene oxide Graphene-semiconductor hybrid photocatalysts for solar fuels Graphene based sensors Graphene composites from bench to clinic Photocatalytic ZnO-graphene hybrids Hydroxyapatite-graphene bioceramics in orthopaedic applications
