Download or read book Two dimensional Superconducting States Near Zero Temperature Quantum Phase Transitions written by Lukas Urban and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The competition between localization and superconductivity in two dimensions has puzzled physicists for decades. In two dimensions, only two electronic phases are predicted to exist at zero temperature 0́3 superconducting and insulating. Contrary to this theoretical expectation, previous transport measurements on 2-dimensional (2D) thin films have found evidence for metallic resistivity down to extremely low temperatures when using either disorder or magnetic field to tune between the superconducting and insulating phases. In this thesis we further investigate the mechanism for the superconductor to insulator transition at zero temperature. We study the destruction of superconductivity due to the application of sufficient magnetic field in 2D films of MoGe and InOx. Unlike previous works, which concentrated on four point resistivity measurements, we focus primarily on measuring the AC conductivity of the 2D films, which probes the superfluid response. Using a contactless technique, we have been able to measure the superconducting transition as a function of temperature and demonstrate the existence of a Kosterlitz-Thouless (KT) transition in zero magnetic field. Applying a magnetic field to the sample, we have been able to observe the suppression of the superconducting response. Temperature sweeps in a magnetic field showed a similar discontinuity as observed in the zero field KT transition, suggesting a similar process for the destruction of superconductivity in both the zero and non-zero magnetic field cases. Analysis of the change in the critical temperature as a function of magnetic field suggests a quantum phase transition at zero temperature.
Download or read book Quantum Phase Transitions and Enhancement of Superconductivity by a Parallel Magnetic Field in Two Dimensional Superconductors written by H. Jeffrey Gardner and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: ABSTRACT: This dissertation describes several studies of superconducting phenomena in two dimensions. We have investigated the superconductor:insulator quantum phase transitions (SITs) tuned by several parameters, namely disorder (d), magnetic field (B), and magnetic impurities (MI). The films have been examined through electrical transport measurements and tunneling spectroscopy. Our experiments are carried out in a unique experimental setup which has allowed us to study these three SITs in situ on the same sample. There are two major theoretical frameworks to describe the superconductor:insulator transitions. One theory calls for a transition from a superconductor to a fermionic insulator. The other points to an bosonic insulator with localized Cooper pairs and itinerant vortices. Our experimental capabilities let us make direct comparisons of the SITs and comment on the nature of transition. We consider the MI:tuned SIT a canonical example of an SIT in the fermionic framework. The resistive transitions in the superconducting state are sharp, the phase boundary is well defined, and the insulating state shows weakly insulating behavior. The B:tuned SIT is representative of a bosonic SIT. In this case, the resistive transitions broaden as magnetic field strength is increased and there is no distinct boundary between the superconducting and insulating phases. Transport reveals a likely activated behavior just on the insulating side of the transition indicative of localized superconductivity. At higher magnetic fields, the temperature dependence weakens, possibly to logarithmic, signaling a break up of Cooper pairs into single electrons. Direct evidence of localized Cooper pairs comes via tunneling spectroscopy measurements on d:tuned granular films where full, bulk superconducting energy gaps are measured in the global insulating state. We have performed transport and tunneling spectroscopy measurements of the d:tuned SIT on amorphous Pb films. The transport behavior is qualitatively similar to what we observed for the MI:tuned SIT. We will also show that our observations of the B:tuned SIT on amorphous Pb films are analogous to the d:tuned SIT on granular films. One goal of our studies was to use tunneling spectroscopy to probe the nature of the insulating states of the d:tuned and MI:tuned SITs. We were only able to complete preliminary measurements on the d:tuned transition, however they are consistent with previous experiments in which increasing disorder leads to a decrease of TC and a concomitant suppression of the normal state density of state (DOS). Our in:house designed and fabricated sample rotation system affords us the opportunity to study the same sample in both perpendicular and parallel magnetic field orientations in situ without breaking vacuum. This capability led us to the observation of parallel magnetic field enhanced superconductivity in amorphous Pb films and the 2:D electron gas at the heteroepitaxial interface of the band insulators LaAlO3 and SrTiO3. We found that the mean field TC of the a:Pb films can be enhanced by as much as 13% above the zero:field value. A qualitatively similar field:enhancement effect has been observed in the LaAlO3/SrTiO3 interfacial superconductor. Moreover, our experiments show the field:enhancement is strongly dependent on the film thickness and magnetic impurity concentration. Clearly, the Bardeen Cooper Schrieffer (BCS) and Ginzburg:Landau (GL) theories of superconductivity do not contain the physics which would account for field:enhanced superconductivity. Presently, we do not have a complete theoretical understanding of the enhancement effect. However, our experimental results have placed significant constraints on any viable theoretical model. In this dissertation, several theoretical explanations of parallel field:enhanced superconductivity are discussed and compared with our observations.
Download or read book Understanding Quantum Phase Transitions written by Lincoln Carr and published by CRC Press. This book was released on 2010-11-02 with total page 756 pages. Available in PDF, EPUB and Kindle. Book excerpt: Quantum phase transitions (QPTs) offer wonderful examples of the radical macroscopic effects inherent in quantum physics: phase changes between different forms of matter driven by quantum rather than thermal fluctuations, typically at very low temperatures. QPTs provide new insight into outstanding problems such as high-temperature superconductivit
Download or read book Introduction to Unconventional Superconductivity written by V.P. Mineev and published by CRC Press. This book was released on 1999-09-21 with total page 204 pages. Available in PDF, EPUB and Kindle. Book excerpt: Unconventional superconductivity (or superconductivity with a nontrivial Cooper pairing) is believed to exist in many heavy-fermion materials as well as in high temperature superconductors, and is a subject of great theoretical and experimental interest. The remarkable progress achieved in this field has not been reflected in published monographs and textbooks, and there is a gap between current research and the standard education of solid state physicists in the theory of superconductivity. This book is intended to meet this information need and includes the authors' original results.
Download or read book Quantum Phase Transitions in Cold Atoms and Low Temperature Solids written by Kaden Richard Alan Hazzard and published by Springer Science & Business Media. This book was released on 2011-06-28 with total page 239 pages. Available in PDF, EPUB and Kindle. Book excerpt: The primary focus of this thesis is to theoretically describe nanokelvin experiments in cold atomic gases, which offer the potential to revolutionize our understanding of strongly correlated many-body systems. The thesis attacks major challenges of the field: it proposes and analyzes experimental protocols to create new and interesting states of matter and introduces theoretical techniques to describe probes of these states. The phenomena considered include the fractional quantum Hall effect, spectroscopy of strongly correlated states, and quantum criticality, among others. The thesis also clarifies experiments on disordered quantum solids, which display a variety of exotic phenomena and are candidates to exhibit so-called "supersolidity." It collects experimental results and constrains their interpretation through theoretical considerations. This Doctoral Thesis has been accepted by Cornell University, Ithaca, USA.
Download or read book Electronic Phase Transitions written by Yu.V. Kopaev and published by Elsevier. This book was released on 2012-12-02 with total page 353 pages. Available in PDF, EPUB and Kindle. Book excerpt: Electronic Phase Transitions deals with topics, which are presently at the forefront of scientific research in modern solid-state theory. Anderson localization, which has fundamental implications in many areas of solid-state physics as well as spin glasses, with its influence on quite different research activities such as neural networks, are two examples that are reviewed in this book. The ab initio statistical mechanics of structural phase transitions is another prime example, where the interplay and connection of two unrelated disciplines of solid-state theory - first principle electronic structure calculations and critical phenomena - has given rise to impressive new insights. Clearly, there is more and more need for accurate, stable numerical simulations of models of interacting electrons, presently discussed with great vigor in connection with high-Tc superconductors where the superconducting transition is close to a magnetic transition, i.e. an antiferromagnetic spin structure. These topics and others are discussed and reviewed by leading experts in the field.
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 Quantum Phase Transitions in Transverse Field Models written by Amit Dutta and published by Cambridge University Press. This book was released on 2015-01-28 with total page 357 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book establishes the fundamental connections between the physics of quantum phase transitions and the technological promise of quantum information.
Download or read book Advances in Superconductivity XII written by T. Yamashita and published by Springer Science & Business Media. This book was released on 2013-11-11 with total page 1162 pages. Available in PDF, EPUB and Kindle. Book excerpt: The 12th International Symposium on Superconductivity was held in Morioka, Japan, October 17-19, 1999. Convened annually since 1988, the symposium covers the whole field of superconductivity from fundamental physics and chemistry to a variety of applications. At the 12th Symposium, a mini-symposium focusing on the two-dimensionality of high-temperature superconductors, or the c-axis transport, and a session on vortex physics were organized. There were also many reports on the recent developments of YBCO-based coated conductors both in the United States and in Japan, AC losses of wires and tapes, developments of bulk materials with strong flux pinning, the recent progress in thin film and junction technologies, and the demonstration of various electronics applications using SQUIDs, microwave devices, and single-flux-quantum (SFQ) digital devices. This volume is a valuable resource for all those working in the field of superconductivity.
Download or read book Quantum Phase Transitions written by Subir Sachdev and published by Cambridge University Press. This book was released on 2011-04-07 with total page 521 pages. Available in PDF, EPUB and Kindle. Book excerpt: Describing the physical properties of quantum materials near critical points with long-range many-body quantum entanglement, this book introduces readers to the basic theory of quantum phases, their phase transitions and their observable properties. This second edition begins with a new section suitable for an introductory course on quantum phase transitions, assuming no prior knowledge of quantum field theory. It also contains several new chapters to cover important recent advances, such as the Fermi gas near unitarity, Dirac fermions, Fermi liquids and their phase transitions, quantum magnetism, and solvable models obtained from string theory. After introducing the basic theory, it moves on to a detailed description of the canonical quantum-critical phase diagram at non-zero temperatures. Finally, a variety of more complex models are explored. This book is ideal for graduate students and researchers in condensed matter physics and particle and string theory.
Download or read book The Vortex State written by N. Bontemps and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 330 pages. Available in PDF, EPUB and Kindle. Book excerpt: One of the most spectacular consequences of the description of the superfluid condensate in superfluid He or in superconductors as a single macroscopic quantum state is the quantization of circulation, resulting in quantized vortex lines. This book draws no distinction between superfluid He3 and He4 and superconductors. The reader will find the essential introductory chapters and the most recent theoretical and experimental progress in our understanding of the vortex state in both superconductors and superfluids, from lectures given by leading experts in the field, both experimentalists and theoreticians, who gathered in Cargèse for a NATO ASI. The peculiar features related to short coherence lengths, 2D geometry, high temperatures, disorder, and pinning are thoroughly discussed.
Download or read book A Modern Approach to Critical Phenomena written by Igor Herbut and published by Cambridge University Press. This book was released on 2007-01-04 with total page 223 pages. Available in PDF, EPUB and Kindle. Book excerpt: Critical phenomena is one of the most exciting areas of modern physics. This 2007 book provides a thorough but economic introduction into the principles and techniques of the theory of critical phenomena and the renormalization group, from the perspective of modern condensed matter physics. Assuming basic knowledge of quantum and statistical mechanics, the book discusses phase transitions in magnets, superfluids, superconductors, and gauge field theories. Particular attention is given to topics such as gauge field fluctuations in superconductors, the Kosterlitz-Thouless transition, duality transformations, and quantum phase transitions - all of which are at the forefront of physics research. This book contains numerous problems of varying degrees of difficulty, with solutions. These problems provide readers with a wealth of material to test their understanding of the subject. It is ideal for graduate students and more experienced researchers in the fields of condensed matter physics, statistical physics, and many-body physics.
Download or read book BCS written by Leon N. Cooper and published by World Scientific. This book was released on 2011 with total page 586 pages. Available in PDF, EPUB and Kindle. Book excerpt: Named a Top Five Book of 2011 by Physics Today, USA.The BCS theory of superconductivity developed in 1957 by Bardeen, Cooper and Schrieffer has been remarkably successful in explaining the properties of superconductors. In addition, concepts from BCS have been incorporated into diverse fields of physics, from nuclear physics and dense quark matter to the current standard model. Practical applications include SQUIDs, magnetic resonance imaging, superconducting electronics and the transmission of electricity. This invaluable book is a compilation of both a historical account and a discussion of the current state of theory and experiment.With contributions from many prominent scientists, it aims to introduce students and researchers to the origins, the impact and the current state of the BCS theory.
Download or read book The Physics of Superconductors written by Karl-Heinz Bennemann and published by Springer Science & Business Media. This book was released on 2011-06-27 with total page 1149 pages. Available in PDF, EPUB and Kindle. Book excerpt: This is the second volume of a comprehensive two-volume treatise on superconductivity that represents the first such publication since the earlier widely acclaimed books by R. Parks. It systematically reviews the basic physics and recent advances in the field. Leading researchers describe the state of the art in conventional phonon-induced superconductivity, high-Tc superconductivity, and in novel superconductivity, including triplet pairing in the ruthenates. The second volume is largely concerned with novel superconductors, such as heavy-fermion metals and organic materials, and also includes granular superconductors. Important new results on current problems are presented in a manner designed to stimulate further research. Numerous illustrations, diagrams and tables make this book especially useful as a reference work for students, teachers and researchers. Volume 1 treats Conventional and High-Tc Superconductors (3-540-43883-1).
Download or read book Dissipative Quantum Mechanics of Nanostructures written by Andrei D. Zaikin and published by CRC Press. This book was released on 2019-05-24 with total page 393 pages. Available in PDF, EPUB and Kindle. Book excerpt: Continuing miniaturization of electronic devices, together with the quickly growing number of nanotechnological applications, demands a profound understanding of the underlying physics. Most of the fundamental problems of modern condensed matter physics involve various aspects of quantum transport and fluctuation phenomena at the nanoscale. In nanostructures, electrons are usually confined to a limited volume and interact with each other and lattice ions, simultaneously suffering multiple scattering events on impurities, barriers, surface imperfections, and other defects. Electron interaction with other degrees of freedom generally yields two major consequences, quantum dissipation and quantum decoherence. In other words, electrons can lose their energy and ability for quantum interference even at very low temperatures. These two different, but related, processes are at the heart of all quantum phenomena discussed in this book. This book presents copious details to facilitate the understanding of the basic physics behind a result and the learning to technically reproduce the result without delving into extra literature. The book subtly balances the description of theoretical methods and techniques and the display of the rich landscape of the physical phenomena that can be accessed by these methods. It is useful for a broad readership ranging from master’s and PhD students to postdocs and senior researchers.
Download or read book Foundations Of Quantum Mechanics In The Light Of New Technology Selected Papers From The Proceedings Of The First Through Fourth International Symposia On Foundations Of Quantum Mechanics written by Yoshimasa Murayama and published by World Scientific. This book was released on 1997-01-03 with total page 500 pages. Available in PDF, EPUB and Kindle. Book excerpt: ”I re-experience once again the stimulating atmosphere of each of the ISQMs: There were theoretical discussions in diverse frontier areas of physics as well as descriptions of beautiful new (or planned) experiments and technologies. From each of the Symposia I always came away with the exciting feeling of how wonderful physics is and how lucky it is to be a physicist in this era.”Chen Ning YangThis volume is selected from the First through Fourth International Symposia on Foundations of Quantum Mechanics. The International Symposia on Foundations of Quantum Mechanics in the Light of New Technology (ISQMs) provide a unique interdisciplinary forum where distinguished theorists and experimentalists of diverse fields of research gather to discuss basic problems in quantum mechanics in the light of new technology. This volume collects 51 papers selected from over 200 papers by many distinguished scientists. It includes articles by C N Yang, J A Wheeler, Y Nambu, L Esaki and M P A Fisher, to name just a few, and contains topics ranging from quantum measurements to quantum cosmology.
Download or read book Observation of Superconductivity in Epitaxially Grown Atomic Layers written by Satoru Ichinokura and published by Springer. This book was released on 2017-11-01 with total page 135 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis presents first observations of superconductivity in one- or two-atomic-scale thin layer materials. The thesis begins with a historical overview of superconductivity and the electronic structure of two-dimensional materials, and mentions that these key ingredients lead to the possibility of the two-dimensional superconductor with high phase-transition temperature and critical magnetic field. Thereafter, the thesis moves its focus onto the implemented experiments, in which mainly two different materials thallium-deposited silicon surfaces and metal-intercalated bilayer graphenes, are used. The study of the first material is the first experimental demonstration of both a gigantic Rashba effect and superconductivity in the materials supposed to be superconductors without spatial inversion symmetry. The study of the latter material is relevant to superconductivity in a bilayer graphene, which was a big experimental challenge for a decade, and has been first achieved by the author. The description of the generic and innovative measurement technique, highly effective in probing electric resistivity of ultra-thin materials unstable in an ambient environment, makes this thesis a valuable source for researchers not only in surface physics but also in nano-materials science and other condensed-matter physics.
