Download or read book Electronic Transport of a 2D Quantum Material WTe2 written by Wenjin Zhao and published by . This book was released on 2020 with total page 101 pages. Available in PDF, EPUB and Kindle. Book excerpt: Quantum materials, such as superconductors, topological insulators, magnets, and Weyl semimetals, are materials whose properties cannot be explained without quantum mechanics. Strong correlation and band topology play very important roles in quantum materials. The study of two-dimensional (2D) quantum materials was triggered by the discovery of graphene, the first atomically thin crystal wherein electrons are confined in a single 2D sheet. In this regime, critical material parameters such as carrier density, electron correlation strength and topology can be modified by electrostatic gate, screening effect and magnetic field, respectively. Moreover, the stacking of different 2D quantum materials enables creation of novel structures which can host new electronic phenomena and realize new device functionalities. All of these make 2D quantum materials a perfect platform to study the physics of strong correlation, magnetism, and topology. This thesis focuses on electronic properties of a 2D quantum material WTe2. In the first part, I will discuss the discovery of the first ferroelectric metal in few-layer WTe2. As WTe2 is thinned down to trilayer and bilayer, it exhibits coexistence of ferroelectric and metallic phases. Then, I will discuss the quantum spin Hall (QSH) edge state of a monolayer WTe2 in three aspects. The spin axis is first established by study of the anisotropy of conductance in an external magnetic field. Then I will show the magnetic proximity effect between the QSH edge and a 2D magnet CrI3. Finally, I will summarize the experiment of spin current injection into the QSH edge.
Download or read book Quantum Electronic Transport in Atomically Layered Topological Insulators written by Valla Fatemi and published by . This book was released on 2018 with total page 180 pages. Available in PDF, EPUB and Kindle. Book excerpt: The merger of topology and symmetry established a new foundation for understanding the physics of condensed matter, beginning with the notion of topological insulators (TIs) for electronic systems. For the time-reversal invariant TIs, a key aspect is the "helical" mode at the boundary of the system - that is, the ID edge of a 2D topological insulator or the 2D surface of a 3D topological insulator. These helical modes represent the extreme limit of spin-orbit coupling in that the spin-degenercy has been completely lifted while preserving time-reversal symmetry. This property is crucial for proposals realizing exotic excitations like the Majorana bound state. In this thesis, I present a series of experiments investigating electronic transport through the boundary modes of 3D and 2D topological insulators, specifically Bi1.5 Sb0.5 Te1.7 Se1.3 and monolayer WTe 2 , respectively. For the case of ultra-thin WTe 2 , I also present experiments detailing investigations of the 2D bulk states, finding a semimetallic state for the trilayer and a superconducting phase for the monolayer, both of which are strongly tunable by the electric field effect. The discovery of 2D topological insulator and 2D superconductor phases within the same material, accessible by standard solid state elecrostatic gates, places WTe2 in a unique situation among both TIs and superconductors, potentially enabling gate-configurable topological devices within a homogenous material platform.
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 Nature of the Electronic States in Monolayer WTe2 written by Bosong Sun and published by . This book was released on 2021 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Quantum materials are those with essential properties that cannot be described in terms of semiclassical particles and elementary quantum mechanics. In these materials, strong electronic correlations or electronic order, such as superconducting or magnetic order, or topologically nontrivial electronic structure play a key role. The study of two-dimensional quantum materials was triggered by the discovery of graphene as the first stable, isolated atomic monolayer. Beyond graphene, the emergence of other atomically thin two-dimensional materials, such as transition metal dichalcogenides, has offered a promising platform for realizing tunable quantum states. This thesis focuses on the nature of electronic states in monolayer tungsten ditelluride (WTe2). In the first part, I will introduce the discovery of the quantum spin Hall insulator (QSHI) state and superconducting state in single layer WTe2. There, the carrier density-dependent phase transition from a topological insulator to superconductor hints at BCS-like excitonic condensation in this exotic material. In the second part, I will address studies of the possibility of forming excitons and an exciton condensate in monolayer WTe2 with both experimental and theoretical evidence. Then, I will show studies of stacking induced ferroelectricity in few-layer WTe2 and illustrate that bilayer WTe2 is another potential excitonic insulator candidate with further study on its insulating state. At the end, I will talk about a selection of other approaches to studying two-dimensional materials and give an outlook to future opportunities in the study.
Download or read book Electronic Transport in 2D Materials with Strong Spin orbit Coupling written by Artem Pulkin and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Mots-clés de l'auteur: 2D materials ; transition metal dichalcogenides ; line defects ; domain boundaries ; spin-orbit coupling ; density functional theory ; ballistic transport ; spin current ; quantum spin Hall effect ; topological insulators.
Download or read book Electronic Transport in Two dimensional Systems in the Quantum Hall Regime written by Vinicio Tarquini and published by . This book was released on 2016 with total page 142 pages. Available in PDF, EPUB and Kindle. Book excerpt: Moreover, probing the breakdown via inner and outer edges reveals a breakdown in discontinuous steps characterized by exactly the Landau level spacing. These results are the first-time evidence for a resonant quantum tunneling mechanism realized through aligning the edge and bulk energy levels. We also explored the fundamental physics of graphene-based devices with an eye focused on possible applications as ultra-high gain and quantum efficiency hybrid graphene-quantum dots phototransistors. We have confirmed that natural graphene presents better transport properties as mobility (10-fold higher) and delta point closer to zero. Also we have been able to observe the anomalous quantum Hall effect, unique to graphene, symbol of the high quality of the device. More experimental work is needed to gain more insights on the real efficiency of the devices and a more efficient fabrication.
Download or read book Quantum Transport Properties in Tungsten Ditelluride Based Devices written by Xurui Zhang and published by . This book was released on 2021 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The success of mechanical exfoliation on graphene has paved a new field of research in two-dimensional (2D) materials. As one of the transition metal dichalcogenides (TMDCs), tungsten ditelluride (WTe2) has attracted a mass of interests since a novel non-saturating positive magnetoresistance was discovered in 2014. A lot of researches in this material have been published, such as band structure studies with angle-resolved photoelectron spectroscopy (ARPES), quantum oscillations in transport measurements, superconductivity in WTe2 etc. It is worth mentioning that the topological properties of WTe2 have been verified in both bulk (type-II Weyl semi-metal) and in monolayer (2D topological insulator) forms. The topological properties make WTe2 a potential candidate for hosting Majorana bound state, which is theoretically predicted to arise from the proximity effect between a s-wave superconductor and the surface states of a topological insulator (TI). This dissertation will present quantum transport studies in multi-layer WTe2, which acts as an intermediate between the bulk and monolayer limits. Our goal is to explore the transport properties in WTe2 itself, and investigate its interaction with other quantum materials, especially superconductors. A series of different types of devices based on multi-layer WTe2, including Hall bars, FET-like devices and Josephson junctions, have been fabricated and measured in the magnetic fields up to 12 T at low temperatures down to 20 mK. In order to improve the performance of the devices, the hexagonal boron nitride (hBN) flakes are used to build sandwiched structures for thin WTe2 flakes. The main results are presented as follows. First, thickness-dependent quantum transport measurements suggest that the novel "turn-on" behavior in WTe2 take the origin of the Kohler's rule in Fermi liquid state. The "turn-on" behavior accompanied by the large magnetoresistance (MR) will be effectively suppressed by the loss of perfect carrier compensation. Strikingly, however, the trend of non-saturation is unaffected at all which indicates the possibility of other origins of the non-saturating MR. In addition, the angle-dependent MR measurements reveal that the electronic 3D nature of multi-layer WTe2 and the Fermi surface anisotropy depends on the sample thickness. Second, we observe an obvious crossover between weak anti-localization (WAL) and weak localization (WL) in an disordered ultrathin WTe2 flake. The mechanism of the crossover shows coexistence and competition among several characteristic lengths, including the dephasing length, the spin-flip length, and the mean free path. Furthermore, the interplay of quantum interference and electron-electron interaction is also observed. Third, an unconventional quasi-3D quantum Hall effect (QHE) is observed in a high quality flake with much lower carrier density and higher mobility than ordinary WTe2. The quasi-3D QHE act as a collection of several weakly-coupled 2D QHE layers, which might be resulted from a dimerization or tetramization effect. Fourth, in the Ta-WTe2-Ta Josephson junctions, supercurrent state is successfully induced into the multi-layer WTe2 by proximity effect. We observe the fast mode superconducting quantum interference pattern, which indicates the presence of edge supercurrent resulted from the intrinsic edge states of WTe2. In addition, the multiple frequencies observed in the interference pattern might be from the terrace structure along the sample edges. Finally, the presence of the multi-dips in differential resistance in the Josephson junctions with incomplete superconducting state marks the multiple Andreev reflections in WTe2, which might be due to the multiple channels formed along the Josephson junction length. Furthermore, the related experimental procedures, improvements and different data processing methods have also been presented in the main text and appendixes.
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 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: A comprehensive and accessible introduction to 2D materials, covering basic physics, electronic and optical properties, and potential applications.
Download or read book Atomic and Electronic Properties of 2D Moir Interfaces written by Astrid Weston and published by Springer Nature. This book was released on 2022-10-06 with total page 148 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis provides the first atomic length-scale observation of the structural transformation (referred to as lattice reconstruction) that occurs in moiré superlattices of twisted bilayer transition metal dichalcogenides (TMDs) at low (θ 2 ̊) twist angles. Such information is essential for the fundamental understanding of how manipulating the rotational twist-angle between two adjacent 2-dimensional crystals subsequently affects their optical and electrical properties./ppStudies using Scanning transmission electron microscopy (STEM), a powerful tool for atomic-scale imaging, were limited due to the complexity of the (atomically-thin) sample fabrication requirements. This work developed a unique way to selectively cut and re-stack monolayers of TMDs with a controlled rotational twist angle which could then be easily suspended on a TEM grid to meet the needs of the atomically thin sample requirements. The fabrication technique enabled the study of the two common stacking-polytypes including 3R and 2H (using MoS2 and WS2 as the example) as well as their structural evolution with decreasing twist-angle./ppAtomic-scale studies were followed by a comprehensive investigation of their electronic properties using scanning probe microscopy and electrical transport measurements of the artificially-engineered structures. The electronic structure of two common stacking-polytypes (3R and 2H) were strikingly different, as revealed by conductive atomic force microscopy. Further studies focused on the 3R-stacking polytype to reveal room-temperature out-of-plane ferroelectricity using tools such as kelvin probe force microscopy, scanning electron microscopy and electrical transport measurements. This work highlights that the unique intrinsic properties of TMDs (i.e. semiconductors with strongly light-matter interaction) combined with the additional twisted degree-of-freedom has great potential to create atomically thin transistors/LEDs with built-in memory storage functions and will further aid in the development of the next generation of optoelectronics.
Download or read book Magnetoresistance in Metals written by A. B. Pippard and published by Cambridge University Press. This book was released on 1989-01-26 with total page 270 pages. Available in PDF, EPUB and Kindle. Book excerpt: First published in 1989, this book contained the first systematic account of magnetoresistance in metals, the study of which has provided solid-state physicists with much valuable information about electron motion in metals. The electrical resistance of a metal is usually changed when a magnetic field is applied to it; at low temperatures the change may be very large indeed and when magnetic breakdown is involved, very complex. Every metal behaves differently, and the effect is highly dependent on the direction of the field relative to the crystal axes. Quite apart from its usefulness for determining the Ferni surfaces of individual metals, the phenomenon presents many interesting problems in its own right; it is the phenomenon, rather than its applications, that Professor Pippard concentrates on in this book. The level of treatment is aimed at readers with a basic knowledge of undergraduate solid-state physics, and makes no great demand on mathematical ability. The text is copiously illustrated with real experimental results.
Download or read book Electronic Transport in Functional Materials and Two Dimensional Hole System written by Shuhao Liu and published by . This book was released on 2018 with total page 120 pages. Available in PDF, EPUB and Kindle. Book excerpt: Understanding the transport properties of semiconductor materials has been a key to the discovery of various intriguing quantum phenomena in condensed matter physics and the development of new semiconductor technologies. In this dissertation, electronic transport properties of the 2D hole system at the GaAs/AlGaAs heterointerface, the exceptional thermoelectric material SnSe and the emerging solar cell material lead halide perovskite are investigated.
Download or read book 21st Century Nanoscience A Handbook written by Klaus D. Sattler and published by CRC Press. This book was released on 2020-11-26 with total page 864 pages. Available in PDF, EPUB and Kindle. Book excerpt: 21st Century Nanoscience - A Handbook: Nanophotonics, Nanoelectronics, and Nanoplasmonics (Volume 6) will be the most comprehensive, up-to-date large reference work for the field of nanoscience. Handbook of Nanophysics by the same editor published in the fall of 2010 and was embraced as the first comprehensive reference to consider both fundamental and applied aspects of nanophysics. This follow-up project has been conceived as a necessary expansion and full update that considers the significant advances made in the field since 2010. It goes well beyond the physics as warranted by recent developments in the field. This sixth volume in a ten-volume set covers nanophotonics, nanoelectronics, and nanoplasmonics. Key Features: Provides the most comprehensive, up-to-date large reference work for the field. Chapters written by international experts in the field. Emphasises presentation and real results and applications. This handbook distinguishes itself from other works by its breadth of coverage, readability and timely topics. The intended readership is very broad, from students and instructors to engineers, physicists, chemists, biologists, biomedical researchers, industry professionals, governmental scientists, and others whose work is impacted by nanotechnology. It will be an indispensable resource in academic, government, and industry libraries worldwide. The fields impacted by nanophysics extend from materials science and engineering to biotechnology, biomedical engineering, medicine, electrical engineering, pharmaceutical science, computer technology, aerospace engineering, mechanical engineering, food science, and beyond.
Download or read book Modeling A C Electronic Transport Through a Two Dimensional Quantum Point Contact written by and published by . This book was released on 1998 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Non layered 2D Materials written by and published by Elsevier. This book was released on 2023-11-20 with total page 370 pages. Available in PDF, EPUB and Kindle. Book excerpt: Semiconductors and Semimetals series, highlights new advances in the field, with this new volume presenting interesting chapters. Each chapter is written by an international board of authors. The existence of this book is a testament to the dedication and expertise of our esteemed authors and contributors from across the globe, all of whom are at the forefront of this rapidly evolving field Serves as your gateway to a comprehensive exploration of non-layered 2D materials Not only teaches you something new but also sparks your creativity and curiosity
Download or read book Electronic Transport in Quantum Matter Systems written by Daniel Destraz and published by . This book was released on 2020 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Two Dimensional Transition Metal Dichalcogenides written by Chi Sin Tang and published by John Wiley & Sons. This book was released on 2023-11-08 with total page 357 pages. Available in PDF, EPUB and Kindle. Book excerpt: Two-Dimensional Transition-Metal Dichalcogenides Comprehensive resource covering rapid scientific and technological development of polymorphic two-dimensional transition-metal dichalcogenides (2D-TMDs) over a range of disciplines and applications Two-Dimensional Transition-Metal Dichalcogenides: Phase Engineering and Applications in Electronics and Optoelectronics provides a discussion on the history of phase engineering in 2D-TMDs as well as an in-depth treatment on the structural and electronic properties of 2D-TMDs in their respective polymorphic structures. The text addresses different forms of in-situ synthesis, phase transformation, and characterization methods for 2D-TMD materials and provides a comprehensive treatment of both the theoretical and experimental studies that have been conducted on 2D-TMDs in their respective phases. Two-Dimensional Transition-Metal Dichalcogenides includes further information on: Thermoelectric, fundamental spin-orbit structures, Weyl semi-metallic, and superconductive and related ferromagnetic properties that 2D-TMD materials possess Existing and prospective applications of 2D-TMDs in the field of electronics and optoelectronics as well as clean energy, catalysis, and memristors Magnetism and spin structures of polymorphic 2D-TMDs and further considerations on the challenges confronting the utilization of TMD-based systems Recent progress of mechanical exfoliation and the application in the study of 2D materials and other modern opportunities for progress in the field Two-Dimensional Transition-Metal Dichalcogenides provides in-depth review introducing the electronic properties of two-dimensional transition-metal dichalcogenides with updates to the phase engineering transition strategies and a diverse range of arising applications, making it an essential resource for scientists, chemists, physicists, and engineers across a wide range of disciplines.
