Download or read book Disorder and Interaction in Low Dimensional Electronic Systems written by Akshay Krishna and published by . This book was released on 2020 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: All electrons are identical and subject to the same forces, yet the materials they make up possess a dazzling diversity of physical properties. The interplay of electron-electron interaction and random disorder is largely responsible for this emergent complexity. This thesis presents some examples of non-trivial behavior arising from simple theoretical models of electronic systems in low dimensions.The first part of this thesis describes modifications to two well-studied models of disorder in one-dimensional non-interacting systems. In the ?Dyson?? model, electrons on a chain hop randomly between nearest neighbors in the absence of an on-site potential. It is shown that a choice of singular hopping distributions induces continuously tunable non-universal behavior in the localization length and density of states at the band center. The next topic is the Anderson model, in which a random potential causes complete breakdown of transport. Adding an energy penalty for the propagation of electrons along one direction truncates the Hilbert space; this leads to the possibility of multifractal behavior, and a mobility edge between localized and extended states.The second part of this thesis focuses on aspects of the quantum Hall effect of a two-dimensional interacting electron gas in a high magnetic field, observed in semiconductor heterostructures, graphene and layered compounds. Here the single particle spectrum resolves into dispersionless and highly degenerate Landau levels (LLs). We study the response of the many-body ground state to band mass anisotropy in the lowest LL and find it to be a nontrivial (and non-analytic) function of interaction type, filling fraction and particle statistics. Finally, this thesis reports on the influence of disorder on nearly flat subbands of the lowest LL, in both the interacting and non-interacting settings. These subbands are obtained by adding a carefully tuned periodic potential. Topologically trivial subbands, with Chern number zero, may host a many-body localized (MBL) phase at large disorder. However, MBL is absent in topologically nontrivial subbands, with nonzero Chern number. This approach enables one to disentangle the roles of topology and dimensionality in destabilizing MBL in the quantum Hall system.

Download or read book New Horizons in Low Dimensional Electron Systems written by H. Aoki and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 471 pages. Available in PDF, EPUB and Kindle. Book excerpt: In Bird of Passage by Rudolf Peierls, we find a paragraph in which he de scribes his Cambridge days in the 1930s: On these [relativistic field theory] problems my main contacts were Dirac, and the younger theoreticians. These included in particular Nevill (now Sir Nevill) Mott, perhaps the friendliest among many kind and friendly people we met then. Professor Kamimura became associated with Sir Rudolf Peierls in the 1950s, when he translated, with his colleagues, Peierls's 1955 textbook, Quantum Theory of Solids, into Japanese. This edition, to which Sir Rudolf himself contributed a preface, benefitted early generations of Japanese solid state physicists. Later in 1974/5, during a sabbatical year spent at the Cavendish Laboratory, Professor Kamimura met and began a long association with Sir Nevill Mott. In particular, they developed ideas for disordered systems. One of the outcomes is a paper coauthored by them on ESR-induced variable range hopping in doped semiconductors. A series of works on disordered systems, together with those on two-dimensional systems, have served as building blocks for Physics of Interacting Electrons in Disordered Systems, in the International Series of Monographs on Physics, coauthored by Aoki and published in 1989 by the Oxford University Press. Soon after Professor Kamimura obtained a D. Sc. in 1959 for the work on the ligand field theory under the supervision ofMasao Kotani, his strong con nections in the international physical community began when he worked at the Bell Telephone Laboratories in 1961/64.

Download or read book New Horizons in Low Dimensional Electron Systems written by Hideo Aoki and published by Springer Science & Business Media. This book was released on 1991-12-31 with total page 498 pages. Available in PDF, EPUB and Kindle. Book excerpt: In Bird of Passage by Rudolf Peierls, we find a paragraph in which he de scribes his Cambridge days in the 1930s: On these [relativistic field theory] problems my main contacts were Dirac, and the younger theoreticians. These included in particular Nevill (now Sir Nevill) Mott, perhaps the friendliest among many kind and friendly people we met then. Professor Kamimura became associated with Sir Rudolf Peierls in the 1950s, when he translated, with his colleagues, Peierls's 1955 textbook, Quantum Theory of Solids, into Japanese. This edition, to which Sir Rudolf himself contributed a preface, benefitted early generations of Japanese solid state physicists. Later in 1974/5, during a sabbatical year spent at the Cavendish Laboratory, Professor Kamimura met and began a long association with Sir Nevill Mott. In particular, they developed ideas for disordered systems. One of the outcomes is a paper coauthored by them on ESR-induced variable range hopping in doped semiconductors. A series of works on disordered systems, together with those on two-dimensional systems, have served as building blocks for Physics of Interacting Electrons in Disordered Systems, in the International Series of Monographs on Physics, coauthored by Aoki and published in 1989 by the Oxford University Press. Soon after Professor Kamimura obtained a D. Sc. in 1959 for the work on the ligand field theory under the supervision ofMasao Kotani, his strong con nections in the international physical community began when he worked at the Bell Telephone Laboratories in 1961/64.

Download or read book Localization and Confinement of Electrons in Semiconductors written by Friedemar Kuchar and published by Springer. This book was released on 1990-12-10 with total page 353 pages. Available in PDF, EPUB and Kindle. Book excerpt: The winter school on Localization and Confinement of Electrons in Semicon ductors was the sixth of a series dealing with new developments in solid~state physics organized by the Austrian Physical Society. The school, which was held in the castle of Mautemdorf, in the federal province of Salzburg, Austria, February 19-23, 1990, was attended by about 200 participants. This is the fourth such winter school to have the proceedings published in the Springer Series in Solid-State Sciences, the earlier ones appearing as Vols. 53, 67 and 83. The contributions of the invited speakers are arranged in seven parts according to topic: quantum boxes and quantum wires; localization and the metal-insulator transition; the integer and fractional quantum Hall effects and electron-electron interactions; tunneling and localization in low-dimensional structures and superlattices; optical properties of confined systems; impurities in quantum well structures; and optical and magnetic properties of dilute mag netic semiconductor quantum well. structures. A particular intention of this book is to present relevant introductory articles alongside the most recent research reports, all written by experts in the fields of localization and condensation of electrons in semiconductors, the quantum Hall effect, lateral superlattices, ballistic transport, etc. The fascinating subject of quantum boxes (dots) and quantum wires is treated in considerable detail. Experimental techniques for producing later ally structured two-dimensional electron gas systems are described together with methods for studying their electrical and optical properties.

Download or read book Low Dimensional Systems written by Tobias Brandes and published by Springer. This book was released on 2008-01-11 with total page 220 pages. Available in PDF, EPUB and Kindle. Book excerpt: Experimental progress over the past few years has made it possible to test a n- ber of fundamental physical concepts related to the motion of electrons in low dimensions. The production and experimental control of novel structures with typical sizes in the sub-micrometer regime has now become possible. In parti- lar, semiconductors are widely used in order to con?ne the motion of electrons in two-dimensional heterostructures. The quantum Hall e?ect was one of the ?rst highlights of the new physics that is revealed by this con?nement. In a further step of the technological development in semiconductor-heterostructures, other arti?cial devices such as quasi one-dimensional ‘quantum wires’ and ‘quantum dots’ (arti?cial atoms) have also been produced. These structures again di?er very markedly from three- and two-dimensional systems, especially in relation to the transport of electrons and the interaction with light. Although the technol- ical advances and the experimental skills connected with these new structures are progressing extremely fast, our theoretical understanding of the physical e?ects (such as the quantum Hall e?ect) is still at a very rudimentary level. In low-dimensional structures, the interaction of electrons with one another and with other degrees of freedoms such as lattice vibrations or light gives rise to new phenomena that are very di?erent from those familiar in the bulk ma- rial. The theoretical formulation of the electronic transport properties of small devices may be considered well-established, provided interaction processes are neglected.

Download or read book Low Dimensional Electronic Systems written by Guenther Neubauer and published by Springer Science & Business Media. This book was released on 2013-03-13 with total page 367 pages. Available in PDF, EPUB and Kindle. Book excerpt: Owing to new physical, technological, and device concepts of low-dimensionalelectronic systems, the physics and fabrication of quasi-zero, one- and two-dimensional systems are rapidly growing fields. The contributions presented in this volume cover results of nanostructure fabrication including recently developed techniques, for example, tunneling probe techniques and molecular beam epitaxy, quantum transport including the integer and fractional quantum Hall effect, optical and transport studies of the two-dimensional Wigner solid, phonon studies of low-dimensional systems, and Si/SiGe heterostructures and superlattices. To the readers new in the field this volume gives a comprehensive introduction and for the experts it is an update of their knowledge and a great help for decisions about future research activities.

Download or read book Strongly Correlated Fermions and Bosons in Low Dimensional Disordered Systems written by Igor V. Lerner and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 405 pages. Available in PDF, EPUB and Kindle. Book excerpt: The physics of strongly correlated fermions and bosons in a disordered envi ronment and confined geometries is at the focus of intense experimental and theoretical research efforts. Advances in material technology and in low temper ature techniques during the last few years led to the discoveries of new physical of atomic gases and a possible metal phenomena including Bose condensation insulator transition in two-dimensional high mobility electron structures. Situ ations were the electronic system is so dominated by interactions that the old concepts of a Fermi liquid do not necessarily make a good starting point are now routinely achieved. This is particularly true in the theory of low dimensional systems such as carbon nanotubes, or in two dimensional electron gases in high mobility devices where the electrons can form a variety of new structures. In many of these sys tems disorder is an unavoidable complication and lead to a host of rich physical phenomena. This has pushed the forefront of fundamental research in condensed matter towards the edge where the interplay between many-body correlations and quantum interference enhanced by disorder has become the key to the understand ing of novel phenomena.

Download or read book Two Non equilibrium Phenomena in Low dimensional Electronic Systems written by Mathias Jacques Rufino and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Magnetization Measurements on Low Dimensional Electron Systems in High Mobility GaAs and SiGe Heterostructures written by and published by Cuvillier Verlag. This book was released on 2005-03-06 with total page 134 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this work, entitled "Magnetization Measurements on Low-Dimensional Electron Systems in High-Mobility GaAs and SiGe Heterostructures", micromechanical cantilever magnetometers have been used to measure the orbital magnetization of low-dimensional electron systems. The magnetization oscillations observed in the experiment at low temperature reflect the ground state energy of the electron systems. In particular we investigated two-dimensional electron systems (2DESs) of different mobility in GaAs as well as a high-mobility 2DES in Si as a function of magnetic field, temperature and tilt angle between 2DES normal and magnetic field. The 2DESs were realized by molecular beam epitaxy of AlGaAs/GaAs and SiGe/Si. Furthermore, GaAs quantum wires have been investigated. In the GaAs 2DESs we observe the de Haas-van Alphen (dHvA) effect at filling factors corresponding to the Fermi energy being located between Landau levels. In a sample of mobility µ = 9 x 106 cm2/Vs the dHvA effect is very close to an ideal sawtooth. Additional dHvA oscillations occur at fillings corresponding to the Fermi energy lying between spin split levels. The latter are found to be strongly enhanced by the Coulomb exchange interaction. In Si we additionally observe a splitting of the two occupied conduction band valleys in high magnetic fields that is also dominated by electron-electron interaction. Measurements in tilted fields revealed the coupling between the electric confinement and the magnetic confinement induced by a parallel magnetic field component. This led to a characteristic dependence of the dHvA effect on the tilt angle. Coincidence measurements have been used as an independent method to determine the spin splitting quantitatively. The valley splitting was found to be independent of the tilt angle. Comparison with calculations based on a model density of states (DOS) showed that a filling factor dependent background DOS has to be assumed in order to quantitatively model the data. This background can be attributed to the influence of the edge states. The measurements on quantum wires with many occupied subbands show that the confinement potential is effectively screened by the electron-electron interaction down to an electronic wire width of 160 nm. The dHvA oscillations directly reflect this effect. Comparison with calculations assuming a parabolic confinement shows that the DOS between Landau levels increases with decreasing wire width. In dieser Arbeit mit dem Titel "Magnetization Measurements on Low-Dimensional Electron Systems in High-Mobility GaAs and SiGe Heterostructures" wurden mikromechanische Cantilever-Magnetometer benutzt, um die orbitale Magnetisierung von niedrigdimensionalen Elektronensystemen zu untersuchen. Die Magnetisierungsoszillationen, die im Experiment bei tiefer Temperatur auftreten, spiegeln den Verlauf der Grundzustandsenergie wider. Im Speziellen wurden zweidimensionale Elektronensysteme (2DES) verschiedener Beweglichkeit in GaAs sowie ein hochbewegliches 2DES in Si als Funktion des Magnetfeldes, der Temperatur und des Verkippungswinkels zwischen 2DES Normale und Magnetfeld untersucht. Die 2DES wurden mittels Molekularstrahlepitaxie von AlGaAs/GaAs und SiGe/Si realisiert. Weiterhin wurden GaAs Quantendrähte untersucht. In den GaAs 2DES wurde der de Haas-van Alphen (dHvA) Effekt an Füllfaktoren beobachtet, die einer Lage der Fermienergie zwischen den Landau-Niveaus entsprechen. In einer Probe mit Beweglichkeit µ = 9 x 106 cm2 ist der dHvA Effekt nahezu perfekt sägezahnförmig. Weitere dHvA Oszillationen treten bei Füllgraden auf, an denen die Fermienergie zwischen spinaufgespaltenen Niveaus liegt. Letztere sind durch die Coulomb-Austauschwechselwirk-ung stark vergrößert. In Si beobachten wir zusätzlich eine energetische Aufspaltung der bei-den besetzten Leitungsband-Täler in starken Magnetfeldern, die ebenfalls von der Elektron-Elektron Wechselwirkung dominiert wird. Messungen in verkippten Magnetfeldern zeigten den Einfluss der Kopplung zwischen dem elektrischen Einschlußpotenzial und dem magnetischen Einschluß aufgrund der parallelen Magnetfeldkomponente. Dies führte zu einer charakteristischen Abhängigkeit des dHvA Effektes vom Verkippungswinkel. Koinzidenz-Messungen wurden als unabhängige Methode benutzt, um die Spin- Aufspaltung quantitativ zu bestimmen. Die Täler-Aufspaltung erwies sich als unabhängig vom Verkippungswinkel. Der Vergleich mit auf einer Modellzustandsdichte basierenden Rechnungen zeigte, daß eine linear vom Füllfaktor abhängige Untergrundzustandsdichte angenommen werden muss, um die Messergebnisse quantitativ zu modellieren. Dieser Untergrund kann dem Einfluss der Randzustände zugeschrieben werden. Die Messungen an Quantendrähten mit vielen besetzten Subbändern zeigen, daß das Einschlußpotenzial bei einer elektronischen Drahtbreite von 160 nm noch effektiv durch die Elektron-Elektron Wechselwirkung abgeschirmt wird. Die dHvA Oszillationen spiegeln diesen Effekt direkt wider. Der Vergleich mit Modellrechnungen für ein parabolisches Einschlußpotenzial zeigt, daß die Zustandsdichte zwischen den Niveaus mit abnehmender Drahtbreite ansteigt.

Download or read book Physics and Chemistry of Low Dimensional Inorganic Conductors written by C. Schlenker and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 477 pages. Available in PDF, EPUB and Kindle. Book excerpt: The field of low-dimensional conductors has been very active for more than twenty years. It has grown continuously and both the inorganic and organic materials have remark able properties, such as charge and spin density waves and superconductivity. The discovery of superconductivity at high temperature in copper-based quasi two-dimensional conducting oxides nearly ten years ago has further enlarged the field and stimulated new research on inorganic conductors. It was obviously impossible to cover such a broad field in a ten day Institute and it seemed pertinent to concentrate on inorganic conductors, excluding the high Tc superconducting oxides. In this context, it was highly desirable to include both physics and chemistry in the same Institute in order to tighten or in some cases to establish links between physicists and chemists. This Advanced Study Institute is the continuation of a series of similar ones which have taken place every few years since 1974. 73 participants coming from 13 countries have taken part in this School at the beautiful site of the Centre de Physique des Houches in the Mont-Blanc mountain range. The scientific programme included more than forty lectures and seminars, two poster sessions and ten short talks. Several discussion sessions were organized for the evenings, one on New Materials, one on New Topics and one on the special problem of the Fermi and Luttinger liquids. The scientific activity was kept high from the beginning to the end of the Institute.

Download or read book Low dimensional Electronic Systems written by and published by . This book was released on 1992 with total page 440 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Electron phonon Interactions in Low dimensional Structures written by Lawrence John Challis and published by . This book was released on 2003 with total page 302 pages. Available in PDF, EPUB and Kindle. Book excerpt: The study of electrons and holes confined to two, one and even zero dimensions has uncovered a rich variety of new physics and applications. This book describes the interaction between these confined carriers and the optic and acoustic phonons within and around the confined regions. Phonons provide the principal channel of energy transfer between the carriers and their surroundings and also the main restriction to their room temperature mobility. But they have many other roles; they provide, for example, an essential feature of the operation of the quantum cascade laser. Since their momenta at relevant energies are well matched to those of electrons, they can also be used to probe electronic properties such as the confinement width of 2D electron gases and the dispersion curve of quasiparticles in the fractional quantum Hall effect. The book describes both the physics of the electron-phonon interaction in the different confined systems and the experimental and theoretical techniques that have been used in its investigation. The experimental methods include optical and transport techniques as well as techniques in which phonons are used as the experimental probe. The aim of the book is to provide an up to date review of the physics and its significance in device performance. It is also written to be explanatory and accessible to graduate students and others new to the field.

Download or read book FUNDAMENTALS OF PHYSICS Volume II written by José L. Mora-Lopez and published by EOLSS Publications. This book was released on 2009-11-10 with total page 326 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fundamentals of Physics is a component of Encyclopedia of Physical Sciences, Engineering and Technology Resources in the global Encyclopedia of Life Support Systems (EOLSS), which is an integrated compendium of twenty Encyclopedias. The Theme on Fundamentals of Physics provides an overview of the modern areas in physics, most of which had been crystallized in the 20th century, is given. The Theme on Fundamentals of Physics deals, in three volumes and cover several topics, with a myriad of issues of great relevance to our world such as: Historical Review of Elementary Concepts in Physics; Laws of Physical Systems; Particles and Fields; Quantum Systems; Order and Disorder in Nature; Topical Review: Nuclear Processes, which are then expanded into multiple subtopics, each as a chapter. These three volumes are aimed at the following five major target audiences: University and College Students, Educators, Professional Practitioners, Research Personnel and Policy Analysts, Managers, and Decision Makers, NGOs and GOs.

Download or read book Lower Dimensional Systems and Molecular Electronics written by Robert M. Metzger and published by Springer Science & Business Media. This book was released on 2013-11-11 with total page 729 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume represents the written account of the NATO Advanced Study Institute "Lower-Dimensional Systems and Molecular Electronics" held at Hotel Spetses, Spetses Island, Greece from 12 June to 23 June 1989. The goal of the Institute was to demonstrate the breadth of chemical and physical knowledge that has been acquired in the last 20 years in inorganic and organic crystals, polymers, and thin films, which exhibit phenomena of reduced dimensionality. The interest in these systems started in the late 1960's with lower-dimensional inorganic conductors, in the early 1970's with quasi-one-dimensional crystalline organic conductors. which by 1979 led to the first organic superconductors, and, in 1977, to the fITSt conducting polymers. The study of monolayer films (Langmuir-Blodgett films) had progressed since the 1930's, but reached a great upsurge in . the early 1980's. The pursuit of non-linear optical phenomena became increasingly popular in the early 1980's, as the attention turned from inorganic crystals to organic films and polymers. And in the last few years the term "moleculw' electronics" has gained ever-increasing acceptance, although it is used in several contexts. We now have organic superconductors with critical temperatures in excess of 10 K, conducting polymers that are soluble and processable, and used commercially; we have films of a few monolayers that have high in-plane electrical conductivity, and polymers that show great promise in photonics; we even have a few devices that function almost at the molecular level.

Download or read book Interaction Processes and Transport Properties of One and Two Dimensional Electronic Systems written by Kwong-Kit Choi and published by . This book was released on 1984 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Electron Electron Interactions in Disordered Systems written by A.L. Efros and published by Elsevier. This book was released on 2012-12-02 with total page 703 pages. Available in PDF, EPUB and Kindle. Book excerpt: ``Electron-Electron Interactions in Disordered Systems'' deals with the interplay of disorder and the Coulomb interaction. Prominent experts give state-of-the-art reviews of the theoretical and experimental work in this field and make it clear that the interplay of the two effects is essential, especially in low-dimensional systems.

Download or read book Conduction and Excitations of Low dimensional Electron Liquid written by Dongxiao Yue and published by . This book was released on 1995 with total page 218 pages. Available in PDF, EPUB and Kindle. Book excerpt: