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Edge Magnetization in Chiral Graphene Nanoribbons and Quantum Anomalous Hall Effect Interfaces in Graphene

Edge Magnetization in Chiral Graphene Nanoribbons and Quantum Anomalous Hall Effect Interfaces in Graphene PDF Author: André Ricardo Carvalho
Publisher:
ISBN: 9783668135864
Category :
Languages : en
Pages : 100

Book Description
Doctoral Thesis / Dissertation from the year 2015 in the subject Physics - Other, course: Graphene, language: English, abstract: This thesis is composed of two theoretical studies related to properties of edge states in nanostructures of graphene monolayers. In the first one, we analyze the magnetic properties of chiral graphene nanoribbons. Chiral edges corresponds to a symmetry property whose mirror image cannot be superposed on to the original one, inversely of an achiral. There are only two cases of achiral nanoribbon: armchair or zigzag edges. Chiral graphene nanoribbons, as well as those with zigzag edges, have localized states that favour to edge magnetization. In our analysis we use the tight-binging (TB) model with an electron-electron Hubbard mean-field interaction term. We show that only the standard tight-binding model with nearest-neighbor hopping is not sufficient to describe the low-energy and magnetic properties of graphene nanoribbons, i.e., the inclusion of next-nearest-neighbor hopping terms is necessary for an accurate modeling. We compare the results from our model with recent data from scanning tunneling spectroscopy and propose a new interpretation for the peaks experimentally observed in the local density of states. The second subject of this thesis corresponds to a study in progress of conducting states from the quantum anomalous Hall effect (QAHE) in graphene in the presence of a periodic exchange field and a Rashba spin-orbit interaction. We call interfaces the point where two systems meet, in this case, a system with positive sign in the exchange field interaction (EF) meet the analogous system with negative sign in the EF. The conducting states appear at the point of meet: gapless interfaces states. To this end, we analyze the formation of gapless states in the change of the sign from exchange field parameter in graphene with Rashba spin-orbit interaction. While the system in QAHE with a constant sign in exchange field has ener

Edge Magnetization in Chiral Graphene Nanoribbons and Quantum Anomalous Hall Effect Interfaces in Graphene

Edge Magnetization in Chiral Graphene Nanoribbons and Quantum Anomalous Hall Effect Interfaces in Graphene PDF Author: André Ricardo Carvalho
Publisher:
ISBN: 9783668135864
Category :
Languages : en
Pages : 100

Book Description
Doctoral Thesis / Dissertation from the year 2015 in the subject Physics - Other, course: Graphene, language: English, abstract: This thesis is composed of two theoretical studies related to properties of edge states in nanostructures of graphene monolayers. In the first one, we analyze the magnetic properties of chiral graphene nanoribbons. Chiral edges corresponds to a symmetry property whose mirror image cannot be superposed on to the original one, inversely of an achiral. There are only two cases of achiral nanoribbon: armchair or zigzag edges. Chiral graphene nanoribbons, as well as those with zigzag edges, have localized states that favour to edge magnetization. In our analysis we use the tight-binging (TB) model with an electron-electron Hubbard mean-field interaction term. We show that only the standard tight-binding model with nearest-neighbor hopping is not sufficient to describe the low-energy and magnetic properties of graphene nanoribbons, i.e., the inclusion of next-nearest-neighbor hopping terms is necessary for an accurate modeling. We compare the results from our model with recent data from scanning tunneling spectroscopy and propose a new interpretation for the peaks experimentally observed in the local density of states. The second subject of this thesis corresponds to a study in progress of conducting states from the quantum anomalous Hall effect (QAHE) in graphene in the presence of a periodic exchange field and a Rashba spin-orbit interaction. We call interfaces the point where two systems meet, in this case, a system with positive sign in the exchange field interaction (EF) meet the analogous system with negative sign in the EF. The conducting states appear at the point of meet: gapless interfaces states. To this end, we analyze the formation of gapless states in the change of the sign from exchange field parameter in graphene with Rashba spin-orbit interaction. While the system in QAHE with a constant sign in exchange field has ener

Electronic Structure and Topological Quantum Phase Transitions in Strained Graphene Nanoribbons

Electronic Structure and Topological Quantum Phase Transitions in Strained Graphene Nanoribbons PDF Author: Fanyao Qu
Publisher:
ISBN:
Category : Technology
Languages : en
Pages :

Book Description
In this chapter, we discuss the new classes of matter, such as the quantum spin Hall (QSH) and quantum anomalous Hall (QAH) states, that have been theoretically predicted and experimentally observed in graphene and beyond graphene systems. We further demonstrate how to manipulate these states using mechanical strain, internal exchange field, and spin-orbit couplings (SOC). Spin-charge transport in strained graphene nanoribbons is also discussed assuming the system in the QAH phase, exploring the prospects of topological devices with dissipationless edge currents. A remarkable zero-field topological quantum phase transition between the time-reversal-symmetry-broken QSH and quantum anomalous Hall states is predicted, which was previously thought to take place only in the presence of external magnetic field. In our proposal, we show as the intrinsic SOC is tuned, how it is possible to two different helicity edge states located in the opposite edges of the graphene nanoribbons exchange their locations. Our results indicate that the strain-induced pseudomagnetic field could be coupled to the spin degrees of freedom through the SOC responsible for the stability of a QSH state. The controllability of this zero-field phase transition with strength and direction of the strain is also explored as additional phase-tuning parameter. Our results present prospect of strain, electric and magnetic manipulation of the QSH, and QAH effect in these novel two-dimensional (2D) materials.

Physics and Chemistry of Graphene (Second Edition)

Physics and Chemistry of Graphene (Second Edition) PDF Author: Toshiaki Enoki
Publisher: CRC Press
ISBN: 0429662793
Category : Science
Languages : en
Pages : 348

Book Description
Graphene has been attracting growing attentions in physics, chemistry, and device applications after the discovery of micromechanically cleaved graphene sheet by A. Geim and K. Novoselov, who were awarded the 2010 Nobel Prize in Physics. The electronic structure of graphene, which is described in terms of massless Dirac fermions, brings about unconventional electronic properties, which are not only an important basic issue in condensed matter physics but also a promising target of cutting-edge electronics/spintronics device applications. Meanwhile, from chemistry aspect, graphene is the extreme of condensed polycyclic hydrocarbon molecules extrapolated to infinite size. Here, the concept on aromaticity, which organic chemists utilize, is applicable. Interesting issues appearing between physics and chemistry are pronounced in nanosized graphene (nanographene), as we recognize the importance of the shape of nanographene in understanding its electronic structure. This book comprehensively discusses the fundamental issues related to the electronic, magnetic, and chemical properties of condensed polycyclic hyodrocarbon molecules, nanographene, and graphene.

Physics of Graphene

Physics of Graphene PDF Author: Hideo Aoki
Publisher: Springer Science & Business Media
ISBN: 331902633X
Category : Science
Languages : en
Pages : 356

Book Description
This book provides a state of the art report of the knowledge accumulated in graphene research. The fascination with graphene has been growing very rapidly in recent years and the physics of graphene is now becoming one of the most interesting as well as the most fast-moving topics in condensed-matter physics. The Nobel prize in physics awarded in 2010 has given a tremendous impetus to this topic. The horizon of the physics of graphene is ever becoming wider, where physical concepts go hand in hand with advances in experimental techniques. Thus this book is expanding the interests to not only transport but optical and other properties for systems that include multilayer as well as monolayer graphene systems. The book comprises experimental and theoretical knowledge. The book is also accessible to graduate students.

Issues in General Physics Research: 2011 Edition

Issues in General Physics Research: 2011 Edition PDF Author:
Publisher: ScholarlyEditions
ISBN: 1464963282
Category : Science
Languages : en
Pages : 8864

Book Description
Issues in General Physics Research / 2011 Edition is a ScholarlyEditions™ eBook that delivers timely, authoritative, and comprehensive information about General Physics Research. The editors have built Issues in General Physics Research: 2011 Edition on the vast information databases of ScholarlyNews.™ You can expect the information about General Physics Research in this eBook to be deeper than what you can access anywhere else, as well as consistently reliable, authoritative, informed, and relevant. The content of Issues in General Physics Research: 2011 Edition has been produced by the world’s leading scientists, engineers, analysts, research institutions, and companies. All of the content is from peer-reviewed sources, and all of it is written, assembled, and edited by the editors at ScholarlyEditions™ and available exclusively from us. You now have a source you can cite with authority, confidence, and credibility. More information is available at http://www.ScholarlyEditions.com/.

Semiconductors

Semiconductors PDF Author: Martin I. Pech-Canul
Publisher: Springer
ISBN: 3030021718
Category : Technology & Engineering
Languages : en
Pages : 596

Book Description
This book is a practical guide to optical, optoelectronic, and semiconductor materials and provides an overview of the topic from its fundamentals to cutting-edge processing routes to groundbreaking technologies for the most recent applications. The book details the characterization and properties of these materials. Chemical methods of synthesis are emphasized by the authors throughout the publication. Describes new materials and updates to older materials that exhibit optical, optoelectronic and semiconductor behaviors; Covers the structural and mechanical aspects of the optical, optoelectronic and semiconductor materials for meeting mechanical property and safety requirements; Includes discussion of the environmental and sustainability issues regarding optical, optoelectronic, and semiconductor materials, from processing to recycling.

Oxford Handbook of Nanoscience and Technology

Oxford Handbook of Nanoscience and Technology PDF Author: A.V. Narlikar
Publisher: Oxford University Press
ISBN: 0199533059
Category : Language Arts & Disciplines
Languages : en
Pages : 957

Book Description
These three volumes are intended to shape the field of nanoscience and technology and will serve as an essential point of reference for cutting-edge research in the field.

Handbook of Spintronics

Handbook of Spintronics PDF Author: Yongbing Xu
Publisher: Springer
ISBN: 9789400768918
Category : Science
Languages : en
Pages : 0

Book Description
Over two volumes and 1500 pages, the Handbook of Spintronics will cover all aspects of spintronics science and technology, including fundamental physics, materials properties and processing, established and emerging device technology and applications. Comprising 60 chapters from a large international team of leading researchers across academia and industry, the Handbook provides readers with an up-to-date and comprehensive review of this dynamic field of research. The opening chapters focus on the fundamental physical principles of spintronics in metals and semiconductors, including an introduction to spin quantum computing. Materials systems are then considered, with sections on metallic thin films and multilayers, magnetic tunnelling structures, hybrids, magnetic semiconductors and molecular spintronic materials. A separate section reviews the various characterisation methods appropriate to spintronics materials, including STM, spin-polarised photoemission, x-ray diffraction techniques and spin-polarised SEM. The third part of the Handbook contains chapters on the state of the art in device technology and applications, including spin valves, GMR and MTJ devices, MRAM technology, spin transistors and spin logic devices, spin torque devices, spin pumping and spin dynamics and other topics such as spin caloritronics. Each chapter considers the challenges faced by researchers in that area and contains some indications of the direction that future work in the field is likely to take. This reference work will be an essential and long-standing resource for the spintronics community.

Advanced Topological Insulators

Advanced Topological Insulators PDF Author: Huixia Luo
Publisher: John Wiley & Sons
ISBN: 111940732X
Category : Technology & Engineering
Languages : en
Pages : 420

Book Description
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.

Topological Insulators and Topological Superconductors

Topological Insulators and Topological Superconductors PDF Author: B. Andrei Bernevig
Publisher: Princeton University Press
ISBN: 1400846730
Category : Science
Languages : en
Pages : 264

Book Description
This graduate-level textbook 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 graduate students and researchers preparing to work in this area, and it will be an essential reference both within and outside the classroom. The book begins with simple concepts such as Berry phases, Dirac fermions, Hall conductance and its link to topology, and the Hofstadter problem of lattice electrons in a magnetic field. It moves on to explain topological phases of matter such as Chern insulators, two- and three-dimensional topological insulators, and Majorana p-wave wires. Additionally, the book covers zero modes on vortices in topological superconductors, time-reversal topological superconductors, and topological responses/field theory and topological indices. The book also analyzes recent topics in condensed matter theory and concludes by surveying active subfields of research such as insulators with point-group symmetries and the stability of topological semimetals. Problems at the end of each chapter offer opportunities to test knowledge and engage with frontier research issues. Topological Insulators and Topological Superconductors will provide graduate students and researchers with the physical understanding and mathematical tools needed to embark on research in this rapidly evolving field.