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This book offers a comprehensive survey of the latest research concerning high-entropy alloy (HEA) superconductors, an emerging topic which has attracted significant attention since their discovery in 2014. HEAs represent a novel class of materials introduced in 2004, renowned for their exceptional mechanical attributes, robust resistance to corrosion, and remarkable thermal stability, among other characteristics. Superconductivity has emerged as a particularly prominent subject in this domain. Recent important findings are robust superconductivity under extraordinarily high pressure or ion irradiation, possible unconventional superconductivity, enhancement of bulk superconductivity, and high critical current density. In this book, HEA superconductors are classified into two primary categories: The first class encompasses alloy systems characterized by body-centered cubic and hexagonal close-packed structures; and the second class comprises intermetallic types. In each of these classes, the authors expound upon the exotic properties, applications, and materials design, aligning with the overarching themes of their work. This book delivers a topical and timely discussion of superconductivity associated with the high-entropy state, the potential applications under consideration, and the intricacies of materials design. These recent discoveries are poised to captivate many researchers in materials science, particularly those engaged in high-entropy alloys and the realm of superconducting properties and technology.

The book explores the properties and behaviors of high-critical-temperature superconductors in the yttrium barium copper oxide (YBCO) system, looking specifically at Y0.5Ln0.5BaSrCu3O6+z compounds, where Ln represents rare earth elements like europium (Eu), samarium (Sm), and (neodymium) Nd. Structured into several chapters, it navigates through key aspects of superconductivity and its characterization. Starting with an introduction to the discovery of high-critical-temperature superconductors and their far-reaching applications, it sheds light on unresolved questions in materials physics, particularly concerning the behavior of the copper(II)-oxide (CuO2) planes and the introduction of additional electronic holes. Emphasizing the pivotal role of the CuO2 planes in shaping material properties above the critical temperature, it also delves into the history of superconductivity, properties of superconducting materials, and various types of superconductors. Phenomenological theories like the London theory, Ginzburg-Landau theory, and Abrikosov's theory of the mixed state in type II superconductors are discussed, along with conventional theories such as the BCS theory and Josephson junctions. The book provides an overview of experimental techniques used to characterize structural, magnetic, and electrical properties of superconductor compounds, including X-ray diffraction, scanning electron microscopy, and magnetometry. Focusing on the structural, magnetic, and electrical properties of Y0.5Ln0.5BaSrCu3O6+z compounds, along with the effects of substitutions and thermal treatments, the book aims to achieve several objectives. These include a comparative study of superconducting and structural properties under various thermal treatments and isovalent substitutions, analysis of magnetic susceptibility and electrical resistivity as functions of temperature, investigation of the evolution of mixed-state properties with changing temperatures, and utilization of the Rietveld crystallographic refinement method to establish correlations between interatomic distances and critical temperatures. Additionally, the book presents the synthesis of studied compounds through solid-state reactions and subsequent thermal treatments, including annealing under oxygen and argon atmospheres. The results of these treatments are discussed in relation to improvements in irreversibility lines, magnetic shielding, and grain quality.

This thesis demonstrates the value of theoretical approaches in the discovery of new superconducting materials. It reports a detailed study of the recently discovered nickel-oxide (nickelate) superconductors using multiple first-principles computational tools, from density functional theory to dynamical mean field theory. In the context of superconductivity, discoveries have generally been linked to serendipitous experimental discovery; this thesis reports some of the few examples of predictions of new superconductors that have later been realized in practice, a prime example of the significance of the methodology it expounds. Overall, it represents a seminal systematic work in the electronic structure theory of the emergent field of nickelate superconductivity.

High efficiency, large scale, stationary computing systems – supercomputers and data centers – are becoming increasingly important due to the movement of data storage and processing onto remote cloud servers. This book is dedicated to a technology particularly appropriate for this application – superconductive electronics, in particular, rapid single flux quantum circuits. The primary purpose of this book is to introduce and systematize recent developments in superconductive electronics into a cohesive whole to support the further development of large scale computing systems. A brief background into the physics of superconductivity and the operation of common superconductive devices is provided, followed by an introduction into different superconductive logic families, including the logic gates, interconnect, and bias current distribution. Synchronization, fabrication, and electronic design automation methodologies are presented, reviewing both widely established concepts and techniques as well as recent approaches. Issues related to memory, synchronization, interconnects, coupling noise, bias networks, signal interfaces, and deep scaling of superconductive structures and design for testability are described, and models, expressions, circuits, algorithms, and design methodologies are discussed and placed in context. The aim of this book is to provide insight and engineering intuition into the design of large scale digital superconductive circuits and systems.

This book presents experimental studies of nonequilibrium phase transitions induced by ac and dc forces in collectively interacting systems—a superconducting vortex system with random pinning. It first shows that a phase transition from reversible to irreversible flow occurs by increasing vortex density as well as amplitude of ac shear, which is indicative of the universality of the reversible-irreversible transition. Two distinct flow regimes are also found in the reversible phase. Next, the book presents new methods for dc driven experiments—transverse mode-locking and transverse current-voltage measurements—and provides convincing evidence of the second-order dynamical transition from disordered plastic to anisotropically ordered smectic flow. Lastly it reports on the first experimental demonstration of the Kibble-Zurek mechanism for the nonequilibrium phase transition.The experimental results indicate that both the reversible-irreversible transition and the dynamical ordering transition belong to the directed percolation universality class which is one of the fundamental classes of nonequilibrium phase transitions. Hence, the findings will be generalized to other nonequilibrium systems and stimulate research on nonequilibrium physics.

This book presents advances in the field of rare-earth (R) – transition metal (M) – boron compounds with extensive references. Since titanium and scandium do not form compounds with rare-earths, the Sc/Ti-M-B series are additionally presented. In each chapter the crystal structures, the complex physical properties as determined from neutron diffraction, magnetic measurements, resonance studies, transport properties and band structure calculations are critical analyzed. The models used in describing the experimental evidence are also presented. Tables with the main properties of the R-M-B compounds are given and representative data are illustrated in figures. In this way, the book provides state-of-the art knowledge and a valuable analysis of up-to-date results in the field. The technical applications, as permanent magnets, thermoelectric and magnetocaloric devices, hydrogen storage are also highlighted along with the authors insights into future directions in the field. The book is ofinterest for scientists involved in the development of the field as well as those working in the technical uses of rare-earth compounds.

This book gathers selected papers from the 28th International Cryogenic Engineering Conference and International Cryogenic Materials Conference 2022 (ICEC28-ICMC 2022), held virtually in Hangzhou, China on 25-29 April 2022, due to COVID-19 pandemic. Highlighting the latest findings on cryogenic engineering and cryogenic materials, it covers topics including: large-scale cryogenic components, processes and systems for refrigeration, separation, and liquefaction of cryogenic fluids, small-scale cryocoolers, cryogenic space applications, thermal insulation, thermal-physical properties of cryogenic fluids and materials, superconducting materials, devices, systems and applications, etc. The book offers valuable information and insights for academic researchers, engineers in the industry, and operators in the cryogenic field.

This book explores the potential of magnetic superconductors in storage systems, specifically focusing on superconducting magnetic energy storage (SMES) systems and using the Spanish electricity system, controlled by Red Eléctrica de España (REE), as an example.The book provides a comprehensive analysis of the economic costs associated with the manufacture and maintenance of SMES systems, as well as a regulatory analysis for their implementation in the complex Spanish electrical system. The analysis also compares this system with the regulations of other countries, providing a comprehensive case study.The book examines the possible economic and environmental benefits of using magnetic superconductors in electrical systems and provides a technical study of the use of these systems in hybrid storage systems that complement each other to optimize network performance. The study is conducted from the perspective of new distribution networks, distributed generation, and the concepts of the smart city. The book also explores potential applications and developments, such as electric vehicles.Overall, this book offers an insightful and comprehensive analysis of the potential of magnetic superconductors in storage systems. It will be an invaluable resource for researchers, engineers, and policymakers interested in the future of energy storage systems

This book elucidates fascinating electronic phenomena of unusual Bi2-square net in layered R2O2Bi (R: rare earth) compounds using two approaches: the fabrication of epitaxial thin films and the synthesis of bulk polycrystalline powders. The Bi2-square net compounds are a promising platform to explore exotic physical properties originating from the interplay between a two-dimensional electronic state and strong spin–orbit coupling; however, there are few reports on Bi2-square net compounds due to the instability of unusual electronic configurations. The book presents the development of synthetic routes for R2O2Bi compounds, such as novel solid phase epitaxy techniques and chemical control of crystal structure, demonstrating the intrinsic physical properties of Bi2-square net for the first time. The most notable finding is the successful induction of two-dimensional superconductivity in Bi2-square net with the coexistence of rich electronic phases. The book also discusses the superconducting mechanisms and the effect of R cation substitution in detail and describes the mechanical properties of Bi2-square net. These findings overturn the results of previous studies of R2O2Bi. The book sheds light on hidden layered compounds, representing a significant advance in the field.

It used to be difficult to reliably fabricate clean heterostructures using magnetic and superconducting layers. Today this is no longer the case; such reproducible superconductor/ferromagnet heterostructures enable the quantitative study of the rich and varied phenomena associated with ferromagnet/superconductor proximity effects. These structures are eminent, suitable candidates for many switching devices, ranging from non-volatile low power memory elements to quantum computing applications involving Josephson junctions.This book's main purpose is to explain how the equilibrium and transport properties of these heterostructures can be accurately calculated starting from a standard BCS type Hamiltonian. The main techniques, including both analytical and numerical methods, are discussed in detail. Results obtained from these calculations are shown to be in excellent quantitative agreement with experiment.This is a theory book, but the theory is neither abstruse nor esoteric. Knowledge of only introductory graduate physics has been assumed; a solid undergraduate training and a bit of perseverance would also be enough. This book can easily be read and understood by experimentalists, and just about anybody can grasp the basics by referring to the figures and explanations. Quite apart from the manifold applications of superconductor/ferromagnet nanostructures, studying them provides us with considerable insights into fundamental physics and the general study of hybrid nanomaterials.

This thesis describes in-depth studies of the remarkable electronic transport within the ultrahigh conductivity delafossite metals PtCoO_2 and PdCoO_2 using the tool of focused ion beam (FIB) microstucturing. Despite being first synthesised over 50 years ago, important questions remain regarding both the origin of the unusually high conductivity of these compounds and the consequences of their unique properties for unconventional electronic transport, such as that within the ballistic regime. The thesis explores both these areas.High-energy electron irradiation is used to examine the effects of deliberately introducing point defects into PdCoO_2 and PtCoO_2, demonstrating that the extremely low resistivity of these materials stems from an extreme purity as high as 1 defect in 120,000 atoms, rather than a novel scattering suppression mechanism. In addition, studies of the electronic transport in micron-scale squares of these metals show that their broadly hexagonal Fermi surfaces lead not only to long range ballistic behaviour but novel ballistic regime phenomena which cannot be observed in materials with a higher-symmetry Fermi surface.

This PhD thesis reports on investigations of several oxide-based materials using advanced infrared and Raman spectroscopy techniques and in combination with external stimuli such as high magnetic or electric field, sptial confinement in thin film heterostructures and the radiation with UV light. This leads to new results in the fields of superconductivity, electronic polarization states and nanoscale phenomena.Among these, the observation of anomalous polar moments is of great relevance for understanding the electric-field-induced metal-to-insulator transistion; and the demonstration that confocal Raman spectroscopy of backfolded acoustic photons in metal-oxide multilayers can be used as a powerful characterization tool for monitoring their interface properties and layer thickness is an important technical development for the engineering of such functional oxide heterostructures.

This book presents comprehensive studies of charge density waves (CDW) in a high-Tc cuprate superconductor using x-ray scattering techniques under uniaxial pressure. Specifically, the work addresses inelastic x-ray scattering studies under uniaxial pressure performed on the underdoped cuprate YBa2Cu3O6.67(p=0.12, Tc=65K) with incoming photon energy in the resonant (E=931.3 eV, Cu-L3 edge) and non-resonant conditions (E=17.794 keV). This is a completely new approach to the investigation of charge density waves. It revealed new features of charge density waves in cuprates, whose properties had previously been inaccessible..

This thesis makes significant advances towards an understanding of superconductivity in the cuprate family of unconventional, high-temperature superconductors. Even though the high-temperature superconductors were discovered over 35 years ago, there is not yet a general consensus on an acceptable theory of superconductivity in these materials. One of the early proposals suggested that collective magnetic excitations of the conduction electrons could lead them to form pairs, which in turn condense to form the superconducting state at a critical temperature Tc. Quantitative calculations of Tc using experimental data were, however, not available to verify the applicability of this magnetic mechanism. In this thesis, the author constructed an angle-resolved photoemission apparatus that could provide sufficiently accurate data of the electronic excitation spectra of samples in the normal state, data which was furthermore unusually devoid of any surface contamination. The author also appliedthe Bethe-Salpeter method to his uncommonly pristine and precise normal state data, and was able to predict the approximate superconducting transition temperatures of different samples. This rare combination of experiment with sophisticated theoretical calculations leads to the conclusion that antiferromagnetic correlations are a viable candidate for the pairing interaction in the cuprate superconductors.

This book provides a thorough overview of methods and approaches to the experimental characterization of superconductors at microwave frequencies, and includes a detailed description of the two main techniques, both based on the use of coplanar waveguide resonators, that the authors employed to investigate the properties of unconventional superconductors. In the second part several case studies are described, covering a large spectrum of materials and issues. Particular emphasis is given to recent hot topics concerning iron-based superconductors, both of fundamental nature and relevant for applications. The book is intended as a learning tool for researchers in the field, and serves as a guide providing inspiring examples of the use of coplanar resonator techniques to address key topics in the field of unconventional superconductivity.

This book covers the flux pinning mechanisms and properties and the electromagnetic phenomena caused by the flux pinning common for metallic, high-Tc and MgB2 superconductors. The condensation energy interaction known for normal precipitates or grain boundaries and the kinetic energy interaction proposed for artificial Nb pins in Nb-Ti, etc., are introduced for the pinning mechanism. Summation theories to derive the critical current density are discussed in detail. Irreversible magnetization and AC loss caused by the flux pinning are also discussed. The loss originally stems from the ohmic dissipation of normal electrons in the normal core driven by the electric field induced by the flux motion.The influence of the flux pinning on the vortex phase diagram in high Tc superconductors is discussed, and the dependencies of the irreversibility field are also described on other quantities such as anisotropy of superconductor, specimen size and electric field strength. Recent developments of critical current properties in various high-Tc superconductors and MgB2 are introduced.The 3rd edition has been thoroughly updated, with a new chapter on critical state model. The mechanism of irreversible properties is discussed in detail. The author provides calculations of pinning loss by the equation of motion of flux lines in the pinning potential and hysteresis loss. The readers will learn why the resultant loss is of hysteresis type in spite of such mechanism. This book aims for graduate students and researchers studying superconductivity as well as engineers working in electric utility industry.

This book addresses new ways to optimize the fabrication process and performance of iron-based superconducting wires and tapes based on the powder-in-tube (PIT) method. Further, it systemically analyzes and enhances the current-carrying ability of wire and tape conductors with regard to chemical addition, mechanical deformation, and heat treatment. The microstructure of the superconducting cores is studied by means of the magneto-optical imaging technique, high-resolution transmission electron microscopy, and flux pinning analysis. This book will benefits all students, researchers, and technical personnel who work in superconducting materials, applied superconductivity, and the power industry.

This book presents an overview of the science of superconducting materials. It covers the fundamentals and theories of superconductivity. Subjects of special interest involving mechanisms of high temperature superconductors, tunneling, transport properties, magnetic properties, critical states, vortex dynamics, etc. are present in the book. It assists as a fundamental resource on the developed methodologies and techniques involved in the synthesis, processing, and characterization of superconducting materials. The book covers numerous classes of superconducting materials including fullerenes, borides, pnictides or iron-based chalcogen superconductors ides, alloys and cuprate oxides. Their crystal structures and properties are described. Thereafter, the book focuses on the progress of the applications of superconducting materials into superconducting magnets, fusion reactors, and accelerators and other superconducting magnets. The applications also cover recent progress in superconducting wires, power generators, powerful energy storage devices, sensitive magnetometers, RF and microwave filters, fast fault current limiters, fast digital circuits, transport vehicles, and medical applications.

This book presents the high-precision analysis of ground states and low-energy excitations in fractional quantum Hall states formed by Dirac electrons, which have attracted a great deal of attention. In particular the author focuses on the physics of fractional quantum Hall states in graphene on a hexagonal boron nitride substrate, which was recently implemented in experiments. The numerical approach employed in the book, which uses an exact numerical diagonalization of an effective model Hamiltonian on a Haldane's sphere based on pseudopotential representation of electron interaction, provides a better understanding of the recent experiments. The book reviews various aspects of quantum Hall effect: a brief history, recent experiments with graphene, and fundamental theories on integer and fractional Hall effects. It allows readers to quickly grasp the physics of quantum Hall states of Dirac fermions, and to catch up on latest research on the quantum Hall effect in graphene.

This textbook lays out the fundamentals of electronic materials and devices on a level that is accessible to undergraduate engineering students with no prior coursework in electromagnetism and modern physics. The initial chapters present the basic concepts of waves and quantum mechanics, emphasizing the underlying physical concepts behind the properties of materials and the basic principles of device operation. Subsequent chapters focus on the fundamentals of electrons in materials, covering basic physical properties and conduction mechanisms in semiconductors and their use in diodes, transistors, and integrated circuits. The book also deals with a broader range of modern topics, including magnetic, spintronic, and superconducting materials and devices, optoelectronic and photonic devices, as well as the light emitting diode, solar cells, and various types of lasers. The last chapter presents a variety of materials with specific novel applications, such as dielectric materials usedin electronics and photonics, liquid crystals, and organic conductors used in video displays, and superconducting devices for quantum computing.Clearly written with compelling illustrations and chapter-end problems, Rezende's Introduction to Electronic Materials and Devices is the ideal accompaniment to any undergraduate program in electrical and computer engineering. Adjacent students specializing in physics or materials science will also benefit from the timely and extensive discussion of the advanced devices, materials, and applications that round out this engaging and approachable textbook.

This book provides a modern introduction to the growth, characterization, and physics of iron-based superconducting thin films. Iron pnictide and iron chalcogenide compounds have become intensively studied key materials in condensed matter physics due to their potential for high temperature superconductivity. With maximum critical temperatures of around 60 K, the new superconductors rank first after the celebrated cuprates, and the latest announcements on ultrathin films promise even more. Thin film synthesis of these superconductors began in 2008 immediately after their discovery, and this growing research area has seen remarkable progress up to the present day, especially with regard to the iron chalcogenides FeSe and FeSe1-xTex, the iron pnictide BaFe2-xCoxAs2 and iron-oxyarsenides.This essential volume provides comprehensive, state-of-the-art coverage of iron-based superconducting thin films in topical chapters with detailed information on thin film synthesis and growth, analytical film characterization, interfaces, and various aspects on physics and materials properties. Current efforts towards technological applications and functional films are outlined and discussed. The development and latest results for monolayer FeSe films are also presented. This book serves as a key reference for students, lecturers, industry engineers, and academic researchers who would like to gain an overview of this complex and growing research area.

This book offers a primer on the fundamental theory of Andreev reflection, a fundamental process in the motion of a Cooper pair, which dominates low-energy electronic transport properties in superconductor junctions including differential conductance and Josephson current. The book concisely describes how Andreev reflection impacts the low-energy physics of electronic transport especially in topologically non-trivial superconductor junctions. In addition, it includes an introduction to topological superconductors, covering topological classification, chiral and helical superconductors, and topological edges. The book is based on the author's lecture notes, used in his intensive lectures and while supervising his upper undergraduate and early graduate students. To fully benefit from this concise primer, readers only need an undergraduate background in quantum mechanics and statistical mechanics. Further, by highlighting Josephson junctions of topological superconductors, thebook offers readers a glimpse into cutting-edge topics.

This book presents the basics of superconductivity and applications of superconducting magnets. It explains the phenomenon of superconductivity, describes theories of superconductivity, and discusses type II and high-temperature cuprate superconductors. The main focus of the book is the application of superconducting magnets in accelerators, fusion reactors and other advanced applications such as nuclear magnetic resonance (NMR), magnetic resonance imaging (MRI), high-gradient magnetic separation (HGMS), and superconducting magnetic energy storage (SMES). This new and significantly extended second edition covers the state of the art in the development of novel superconductors for advanced magnet applications, as well as the production of practical superconducting wires, tapes, and ultra high current cables used for high-field magnets. It includes two new chapters each devoted to MgB2 and Fe-based superconductors, and discusses the recently developed and world record-setting 45.5-Tesla magnetic field generated by a combination of conventional and high-temperature cuprate superconducting magnets. In addition, it discusses the status and outlook of all current and future nuclear fusion reactors worldwide. The chapter on accelerators includes the ongoing efforts to build high luminosity LHC (HL-LHC), the high-energy 28 TeV LHC (HE-LHC), the future circular collider (FCC) at CERN, and the just launched electro-ion collider (EIC) at Brookhaven National Laboratory. The book is based on the long-standing experience of the author in studying superconducting materials, building magnets and delivering numerous lectures to research scholars and students. The book provides comprehensive and fundamental knowledge in the field of applied superconductivity, greatly benefiting researchers and graduate students wishing to learn more about the various aspects of superconductivity and advanced magnet applications.

A strong spin-orbit interaction and Coulomb repulsion featuring strongly correlated d- and f-electron systems lead to various exotic phase transition including unconventional superconductivity and magnetic multipole order. However, their microscopic origins are long standing problem since they could not be explained based on conventional Migdal-Eliashberg theorem. The book focuses on many-body correlation effects beyond conventional theory for the d- and f-electron systems, and theoretically demonstrates the correlations to play significant roles in “mode-coupling” among multiple quantum fluctuations, which is called U-VC here. The following key findings are described in-depth: (i) spin triplet superconductivity caused by U-VC, (ii) being more important U-VC in f-electron systems due to magnetic multipole degrees of freedom induced by a spin-orbit interaction, and (iii) s-wave superconductivity stabilized cooperatively by antiferromagnetic fluctuations and electron-phonon interaction contrary to conventional understanding. The book provides meaningful step for revealing essential roles of many-body effects behind long standing problems in strongly correlated materials.

This book describes the history of and recent developments in cobaltite and the spin-crossover (SC) phenomena. It offers readers an overview of essential research conducted on cobaltite and introduces them to the fundamentals of condensed matter physics research.The book consists of two parts. The first part reviews SC phenomena, covering the fundamental physics of SC phenomena and basic material properties of cobaltite. The second part focuses on recent topics in SC cobaltite, including the optical and dynamical features of cobaltite, thin material fabrication, and thermoelectric properties. The comprehensive coverage and clearly structured topics will especially appeal to newcomers to the field of state-of-the-art research on cobaltite and SC physics.

This thesis contains three breakthrough results in condensed matter physics. Firstly, broken reflection symmetry in the hidden-order phase of the heavy-fermion material URu2Si2 is observed for the first time. This represents a significant advance in the understanding of this enigmatic material which has long intrigued the condensed matter community due to its emergent long range order exhibited at low temperatures (the so-called “hidden order”). Secondly and thirdly, a novel collective mode (the chiral spin wave) and a novel composite particle (the chiral exciton) are discovered in the three dimensional topological insulator Bi2Se3. This opens up new avenues of possibility for the use of topological insulators in photonic, optoelectronic, and spintronic devices. These discoveries are facilitated by using low-temperature polarized Raman spectroscopy as a tool for identifying optically excited collective modes in strongly correlated electron systems and three-dimensional topological insulators.

This thesis presents pioneering work in the relatively new field of focused ion beam (FIB) sculpting of single crystals to produce bespoke devices and enable the investigation of physics that cannot be studied in bulk samples. It begins with a comprehensive and didactic account of how to achieve this sculpting, revealing the ‘tricks of the trade'of state-of-the-art FIB microstructuring. In subsequent chapters, the author presents ground-breaking results obtained from microstructures of the delafossite oxide metal PdCoO2 and the heavy fermion superconductor CeIrIn5. In these elegant, forefront experiments, a new form of directional ballistic transport in the ultra-pure delafossites is described and explained. Furthermore, a new way to spatially modulate superconductivity induced by strain is demonstrated with electrical transport measurements that agree well with predictions based on thermoelastic finite element simulations.

This compact undergraduate textbook provides a concise yet thorough introduction to the fundamentals of solid-state physics, while also briefly discussing the historical context surrounding key scholars in the field. The vivid explanations and unique didactic approach adopted in the book aim to generate interest in these subjects while also serving as a motivating primer and supporting companion for studying more detailed and advanced textbooks in solid-state physics. The book is also suitable as a quick refresher for students preparing for examinations. The third edition features many extensions, including an up-to-date discussion of topological materials, a rapidly developing area at the forefront of solid-state physics. Primarily concentrating on the electric and magnetic properties of materials, the book will benefit undergraduate students in the fields of physics, materials science, and electrical engineering.

This book puts forward a modern classification theory for superconducting gap nodes, whose structures can be observed by experiments and are essential for understanding unconventional superconductivity. In the first part of the book, the classification method, based on group theory and K theory, is introduced in a step-by-step, pedagogical way. In turn, the latter part presents comprehensive classification tables, which include various nontrivial gap (node) structures, which are not predicted by the Sigrist-Ueda method, but are by the new method. The results obtained here show that crystal symmetry and/or angular momentum impose critical constraints on the superconducting gap structures. Lastly, the book lists a range of candidate superconductors for the nontrivial gap nodes. The classification methods and tables presented here offer an essential basis for further investigations into unconventional superconductivity. They indicate that previous experimental studies should bereinterpreted, while future experiments should reflect the new excitation spectrum.

This book offers an overview of polariton Bose–Einstein condensation and the emerging field of polaritonics, providing insights into the necessary theoretical basics, technological aspects and experimental studies in this fascinating field of science. Following a summary of theoretical considerations, it guides readers through the rich physics of polariton systems, shedding light on the concept of the polariton laser, polariton microcavities, and the technical realization of optoelectronic devices with polaritonic emissions, before discussing the role of external fields used for the manipulation and control of exciton–polaritons. A glossary provides simplified summaries of the most frequently discussed topics, allowing readers to quickly familiarize themselves with the content.The book pursues an uncomplicated and intuitive approach to the topics covered, while also providing a brief outlook on current and future work. Its straightforward content will make it accessible to a broad readership, ranging from research fellows, lecturers and students to interested science and engineering professionals in the interdisciplinary domains of nanotechnology, photonics, materials sciences and quantum physics.

Effects of many-body interactions and superconducting correlations have become central questions in the quantum transport community. While most previous works investigating current fluctuations in nanodevices have been restricted to the stationary regime, Seoane's thesis extends these studies to the time domain. It provides relevant information about the time onset of electronic correlations mediated by interactions and superconductivity. This knowledge is essential for the development of fast electronic devices, as well as novel applications requiring fast manipulations, such as quantum information processing. In addition, the thesis establishes contact with issues of broad current interest such as non-equilibrium quantum phase transitions.

This thesis introduces a systematic study on Second Generation (2G) High Temperature Superconductors (HTS), covering a novel design of an advanced medical imaging device using HTS, and an in-depth investigation on the losses of HTS.The text covers the design and simulation of a superconducting Lorentz Force Electrical Impedance Tomography. This is potentially a significant medical device that is more efficient and compact than an MRI, and is capable of detecting early cancer, as well as other pathologies such stroke and internal haemorrhages. It also presents the information regarding the fundamental physics of superconductivity, concentrating on the AC losses in superconducting coils and tapes.Overall, the thesis signifies an important contribution to the investigation of High Temperature Superconductors. This thesis will be beneficial to the development of advanced superconducting applications in healthcare as well as more broadly in electrical and energy systems.

This book discusses non-equilibrium quantum many-body dynamics, recently explored in an analog quantum simulator of strongly correlated ultracold atoms. The first part presents a field-theoretical analysis of the experimental observability of the Higgs amplitude mode that emerges as a relativistic collective excitation near a quantum phase transition of superfluid Bose gases in an optical lattice potential. The author presents the dynamical susceptibilities to external driving of the microscopic parameters, taking into account a leading-order perturbative correction from quantum and thermal fluctuations and shows clear signatures of the Higgs mode in these observables. This is the first result that strongly supports the stability of the Higgs mode in three-dimensional optical lattices even in the presence of a spatially inhomogeneous confinement potential and paves the way for desktop observations of the Higgs mode. In the second part, the author applies the semi-classical truncated-Wigner approximation (TWA) to far-from-equilibrium quantum dynamics. Specifically, he considers the recent experiments on quantum-quench dynamics in a Bose-Hubbard quantum simulator. A direct comparison shows remarkable agreement between the numerical results from TWA and the experimental data. This result clearly indicates the potential of such a semi-classical approach in reliably simulating many-body systems using classical computers. The book also includes several chapters providing comprehensive reviews of the recent studies on cold-atomic quantum simulation and various theoretical methods, including the Schwinger-boson approach in strongly correlated systems and the phase-space semi-classical method for far-from-equilibrium quantum dynamics. These chapters are highly recommended to students and young researchers who are interested in semi-classical approaches in non-equilibrium quantum dynamics.

This volume contains extended abstracts of the 10 plenary lectures, 27 invited symposium lectures and ap- proximately 300 contributed papers that were presented at the 25th Congress Ampère. The contributions cover the full range of magnetic resonance and radiospectroscopy and their applications in physics, chemical physics, medicine and biology. Advanced NMR and ESR techniques are treated, as are their applications to novel materials.

This is the final volume of Heisenberg's Collected Works. It contains his papers on a (nonlinear) unified theory of elementary particles, as well as his contribution to superconductivity and multiparticle production. Especially interesting is the first group of papers, which is split intotwo sections dealing with, firstly, the formulation of the famous nonlinear spinor equation and, secondly,its applications. Among others the reader willfind a thorough discussion of Heisenberg's collaboration with W. Pauli on these matters. Illuminating annotations to the various sections in this volume have been provided by H. Koppe, R. Hagedorn and the editors.

This thesis presents analytical theoretical studies on the interplay between charge density waves (CDW) and superconductivity (SC) in the actively studied transition-metal dichalcogenide 1T-TiSe2. It begins by reapproaching a years-long debate over the nature of the phase transition to the commensurate CDW (CCDW) state and the role played by the intrinsic tendency towards excitonic condensation in this system. A Ginzburg-Landau phenomenological theory was subsequently developed to understand the experimentally observed transition from commensurate to incommensurate CDW (ICDW) order with doping or pressure, and the emergence of a superconducting dome that coexists with ICDW. Finally, to characterize microscopically the effects of the interplay between CDW and SC, the spectrum of CDW fluctuations beyond mean-field was studied in detail. In the aggregate, the work reported here provides an encompassing understanding of what are possibly key microscopic underpinnings of the CDWand SC physics in TiSe2.

This book introduces the physical principles behind levitation with superconductors, and includes many examples of practical magnetic levitation demonstrations using superconducting phenomena. It features more than twenty examples of magnetic levitation in liquid nitrogen using high temperature superconductors and permanent magnets, all invented by the author. The book includes the demonstration of suspension phenomenon induced by magnetic flux pinning as well as magnetic levitation by the Meissner effect. It shows how superconducting magnetic levitation and suspension phenomena fire the imagination and provide scientific insight and inspiration. This book will be a useful experimental guide and teaching resource for those working on superconductivity, and a fascinating text for undergraduate and graduate students.

This book deals with the study of superconductivity in systems with coexisting wide and narrow bands. It has been previously suggested that superconductivity can be enhanced in systems with coexisting wide and narrow bands when the Fermi level is near the narrow band edge. In this book, the authors study two problems concerning this mechanism in order to: (a) provide a systematic understanding of the role of strong electron correlation effects, and (b) propose a realistic candidate material which meets the ideal criteria for high-Tc superconductivity. Regarding the role of strong correlation effects, the FLEX+DMFT method is adopted. Based on systematic calculations, the pairing mechanism is found to be indeed valid even when the strong correlation effect is considered within the formalism. In the second half of the book, the authors propose a feasible candidate material by introducing the concept of the “hidden ladder” electronic structure, arising from the combination of the bilayer lattice structure and the anisotropic orbitals of the electrons. As such, the book contributes a valuable theoretical guiding principle for seeking unknown high-Tc superconductors.

This book provides a comprehensive and up-to-date description of the Josephson effect, a topic of never-ending interest in both fundamental and applied physics. In this volume, world-renowned experts present the unique aspects of the physics of the Josephson effect, resulting from the use of new materials, of hybrid architectures and from the possibility of realizing nanoscale junctions. These new experimental capabilities lead to systems where novel coherent phenomena and transport processes emerge. All this is of great relevance and impact, especially when combined with the didactic approach of the book. The reader will benefit from a general and modern view of coherent phenomena in weakly-coupled superconductors on a macroscopic scale. Topics that have been only recently discussed in specialized papers and in short reviews are described here for the first time and organized in a generalframework. An important section of the book is also devoted to applications, with focus on long-term, future applications. In addition to a significant number of illustrations, the book includes numerous tables for comparative studies on technical aspects.

This thesis deals with topological orders from two different perspectives: from a condensed matter point of view, where topological orders are considered as breakthrough phases of matter; and from the emerging realm of quantum computation, where topological quantum codes are considered the most appealing platform against decoherence. The thesis reports remarkable studies from both sides. It thoroughly investigates a topological order called the double semion model, a counterpart of the Kitaev model but exhibiting richer quasiparticles as excitations. A new model for symmetry enriched topological order is constructed, which adds an onsite global symmetry to the double semion model. Using this topological phase, a new example of topological code is developed, the semion code, which is non-CSS, additive, non-Pauli and within the stabiliser formalism.Furthermore, the thesis analyses the Rashba spin-orbit coupling within topological insulators, turning the helical edge states into generic edges modes with potential application in spinstronics. New types of topological superconductors are proposed and the novel properties of the correspondingly created Majorana fermions are investigated. These Majorana fermions have inherent properties enabling braiding and the performance of logical gates as fundamental blocks for a universsal quantum computator.

A new experimental method – the'Stiffnessometer', is developed to measure elementary properties of a superconductor, including the superconducting stiffness and the critical current. This technique has many advantages over existing methods, such as: the ability to measure these properties while minimally disturbing the system; the ability to measure large penetration depths (comparable to sample size), as necessary when approaching the critical temperature; and the ability to measure critical currents without attaching contacts and heating the sample. The power of this method is demonstrated in a study of the penetration depth of LSCO, where striking evidence is found for two separate critical temperatures for the in-plane and out-of-plane directions. The results in the thesis are novel, important and currently have no theoretical explanation. The stiffnessometer in a tool with great potential to explore new grounds in condensed matter physics.

This thesis devotes three introductory chapters to outlining basic recipes for constructing the quantum Hamiltonian of an arbitrary superconducting circuit, starting from classical circuit design. Since a superconducting circuit is one of the most promising platforms for realizing a practical quantum computer, anyone who is starting out in the field will benefit greatly from this introduction. The second focus of the introduction is the ultrastrong light-matter interaction (USC), where the latest developments are described. This is followed by three main research works comprising quantum memory in USC; scaling up the 1D circuit to a 2D lattice configuration; creation of Noisy Intermediate-Scale Quantum era quantum error correction codes and polariton-mediated qubit-qubit interaction. The research work detailed in this thesis will make a major contribution to the development of quantum random access memory, a prerequisite for various quantum machine learningalgorithms and applications.​

This book explores the relationship between electronic correlations, dimensionality, inhomogeneities, and superconductivity in low-dimensional systems by studying single crystals of the quasi-one-dimensional Na2–δMo6Se6, composed of MoSe filaments weakly coupled by Na atoms and subject to intrinsic disorder (δ > 0). It shows that the Na2-δMo6Se6 displays strong electronic correlations in its normal state, whereas a superconducting ground state emerges from Anderson localized electrons. Two novel behaviors of the superconducting state are observed: first, a disorder induced enhancement of the superconducting transition temperature; second, a reentrant phase coherence with increasing temperature, magnetic field, and current. It also analyzes the intrinsic properties of Na2-δMo6Se6 are analyzed to offer a thorough understanding of these phenomena. The emergence of superconductivity in such low-dimensional systems provides a fruitful playground to explore electronic order and correlations.

This book covers basic and advanced aspects in the field of Topological Matter. The chapters are based on the lectures presented during the Topological Matter School 2017. It provides graduate level content introducing the basic concepts of the field, including an introductory session on group theory and topological classification of matter. Different topological phases such as Weyls semi-metals, Majoranas fermions and topological superconductivity are also covered. A review chapter on the major experimental achievements in the field is also provided. The book is suitable not only for master, graduate and young postdoctoral researchers, but also to senior scientists who want to acquaint themselves with the subject.

This book is a wide-ranging survey of the physics of out-of-equilibrium systems of correlated electrons, ranging from the theoretical, to the numerical, computational and experimental aspects. It starts from basic approaches to non-equilibrium physics, such as the mean-field approach, then proceeds to more advanced methods, such as dynamical mean-field theory and master equation approaches. Lastly, it offers a comprehensive overview of the latest advances in experimental investigations of complex quantum materials by means of ultrafast spectroscopy.

The book addresses several aspects of thermodynamics and correlations in the strongly-interacting regime of one-dimensional bosons, a topic at the forefront of current theoretical and experimental studies. Strongly correlated systems of one-dimensional bosons have a long history of theoretical study. Their experimental realisation in ultracold atom experiments is the subject of current research, which took off in the early 2000s. Yet these experiments raise new theoretical questions, just begging to be answered. Correlation functions are readily available for experimental measurements. In this book, they are tackled by means of sophisticated theoretical methods developed in condensed matter physics and mathematical physics, such as bosonization, the Bethe Ansatz and conformal field theory. Readers are introduced to these techniques, which are subsequently used to investigate many-body static and dynamical correlation functions.

This ​thesis reports a major breakthrough in discovering the superconducting mechanism in CeCoIn5, the “hydrogen atom” among heavy fermion compounds. By developing a novel theoretical formalism, the study described herein succeeded in extracting the crucial missing element of superconducting pairing interaction from scanning tunneling spectroscopy experiments. This breakthrough provides a theoretical explanation for a series of puzzling experimental observations, demonstrating that strong magnetic interactions provide the quantum glue for unconventional superconductivity. Additional insight into the complex properties of strongly correlated and topological materials was provided by investigating their non-equilibrium charge and spin transport properties. The findings demonstrate that the interplay of magnetism and disorder with strong correlations or topology leads to complex and novel behavior that can be exploited to create the next generation of spin electronics and quantum computing devices.

This thesis introduces the concept of'thermal pure quantum (TPQ) states', which are pure quantum states in equilibrium. The author establishes a new formulation of statistical mechanics based on the TPQ states. This formulation allows us to obtain not only mechanical variables but also thermodynamic variables such as entropy and free energy from a single TPQ state. Furthermore, the formulation provides a new physical description in which all fluctuations including thermally driven ones are uniquely identified to be quantum fluctuations.The use of TPQ formulation has practical advantages in its application to numerical computations and allows for significant reduction in computation cost in numerics. For demonstration purposes, a numerical computation based on TPQ formulation is applied to a frustrated two-dimensional quantum spin model, and the result is also included in this book.

This book studies the structural, magnetic and electronic properties of, as well as magnetic excitations in, high-temperature BaFe2-xNixAs2 superconductors using neutron diffraction and neutron spectroscopic methods. It describes the precise determination of the phase diagram of BaFe2-xNixAs2, which demonstrates strong magnetoelastic coupling and avoided quantum criticality driven by short-range incommensurate antiferromagnetic order, showing cluster spin glass behavior. It also identifies strong nematic spin correlations in the tetragonal state of uniaxial strained BaFe2-xNixAs2. The nematic correlations have similar temperature and doping dependence as resistivity anisotropy in detwinned samples, which suggests that they are intimately connected. Lastly, it investigates doping evolution of magnetic excitations in overdoped BaFe2-xNixAs2 and discusses the links with superconductivity. This book includes detailed neutron scattering results on BaFe2-xNixAs2 and an introduction to neutron scattering techniques, making it a useful guide for readers pursuing related research.

This thesis presents various characteristics of 122-type iron pnictide (FeSC) such as crystal and electronic structure, carrier-doping effect, and impurity-scattering effect, using transport, magnetization, specific heat, single-crystal X-ray diffraction, and optical spectral measurements. Most notably the measurement on the magnetic fluctuation in the material successfully explains already known unusual electronic properties, i.e., superconducting gap symmetry, anisotropy of in-plane resistivity in layered structure, and charge dynamics; and comparing them with those of normal phase, the controversial problems in FeSCs are eventually settled. The thesis provides broad coverage of the physics of FeSCs both in the normal and superconducting phase, and readers therefore benefit from the efficient up-to-date study of FeSCs in this thesis. An additional attraction is the detailed description of the experimental result critical for the controversial problems remaining since the discovery of FeSC in 2008, which helps readers follow up recent developments in superconductor research.