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This book provides expert coverage of modern and novel aspects of the study of vortex matter, dynamics, and pinning in nanostructured and multi-component superconductors. Vortex matter in superconducting materials is a field of enormous beauty and intellectual challenge, which began with the theoretical prediction of vortices by A. Abrikosov (Nobel Laureate). Vortices, vortex dynamics, and pinning are key features in many of today’s human endeavors: from the huge superconducting accelerating magnets and detectors at the Large Hadron Collider at CERN, which opened new windows of knowledge on the universe, to the tiny superconducting transceivers using Rapid Single Flux Quanta, which have opened a revolutionary means of communication. In recent years, two new features have added to the intrinsic beauty and complexity of the subject: nanostructured/nanoengineered superconductors, and the discovery of a range of new materials showing multi-component (multi-gap) superconductivity. In this book, leading researchers survey the most exciting and important recent developments in the field. Topics covered include: the use of scanning Hall probe microscopy to visualize interactions of a single vortex with pinning centers; Magneto-Optical Imaging for investigating what vortex avalanches are, why they appear, and how they can be controlled; and the vortex interactions responsible for the second magnetization peak. Other chapters discuss nanoengineered pinning centers of vortices for improved current-carrying capabilities, current anisotropy in cryomagnetic devices in relation to the pinning landscape, and the new physics associated with the discovery of new superconducting materials with multi-component superconductivity. The book offers something for almost everybody interested in the field: from experimental techniques to visualize vortices and study their dynamics, to a state-of-the-art theoretical microscopic approach to multicomponent superconductivity. Focuses on some of the hottest topics in superconductivity research Covers theory, experiment, and applications Features chapters from world-renowned experts who have made major advances in the field Suitable for advanced undergraduate and graduate students through experienced academic and industry researchers.
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This is the first book that provides a detailed summary of one of the most successful new condensed matter theories - dynamical mean-field theory (DMFT) - in both static and dynamical cases of systems of different sizes. DMFT is one of the most successful approaches to describe the physical properties of systems with strong electron-electron correlations such as bulk materials, multi-layers, surfaces, 2D materials and nanostructures in both metallic and insulating phases. Strongly correlated materials usually include partially-filled localized d- or f-orbitals, and DMFT takes into account crucial for these systems time-resolved interaction between electrons when they "meet" on one atom and occupy one of these orbitals. The First Part of the book covers the general formalism of DMFT as a many-body theory, followed by generalizations of the approach on the cases of finite systems and out-of-equilibrium regime. In the last Chapter of the First Part we discuss generalizations of the approach on the case when the non-local interactions are taken into account. The Second Part of the book covers methodologies of merging DMFT with ab initio static Density Functional Theory (DFT) and Time-Dependent DFT (TDDFT) approaches. Such combined DFT+DMFT and DMFT+TDDFT computational techniques allow one to include the effects of strong electron-electron correlations at the accurate ab initio level. These tools can be applied to complex multi-atom multi-orbital systems currently not accessible to DMFT. The book helps broad audiences of students and researchers from the theoretical and computational communities of condensed matter physics, material science, and chemistry to become familiar with this state-of-art approach and to use it for reaching a deeper understanding of the properties of strongly correlated systems and for synthesis of new technologically-important materials. .
Thermal properties of solids --- Physicochemistry --- supergeleiding --- fysicochemie
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For emerging energy saving technologies superconducting materials with superior performance are needed. Such materials can be developed by manipulating the "elementary building blocks" through nanostructuring. For superconductivity the "elementary blocks" are Cooper pair and fluxon (vortex). This book presents new ways how to modify superconductivity and vortex matter through nanostructuring and the use of nanoscale magnetic templates. The basic nano-effects, vortex and vortex-antivortex patterns, vortex dynamics, Josephson phenomena, critical currents, and interplay between superconductivity and ferromagnetism at the nanoscale are discussed. Potential applications of nanostructured superconductors are also presented in the book.
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This thesis sheds important new light on the puzzling properties of Strontium Ruthenate. Using a sophisticated weak-coupling approach, exact within certain limits, it shows that proper treatment of spin-orbit and multi-band effects is crucial to the physics. Based on the results of these calculations, it resolves a crucial, long-standing puzzle in the field: It demonstrates why the experimentally observed time-reversal breaking is not incompatible with the observed lack of measurable edge currents. Lastly, the thesis makes predictions for the properties of the material under uniaxial strain, which are in good agreement with recent experiments —resolving the mystery of the so-called 3K phase, and suggesting the intriguing possibility that under strain the superconductor may become conventional.
Mathematical physics --- Thermal properties of solids --- supergeleiding --- thermodynamica --- theoretische fysica
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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.
Thermal properties of solids --- Materials sciences --- supergeleiding --- materiaalkennis
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This thesis presents an exact theoretical study of dynamical correlation functions in different phases of a two-dimensional quantum spin liquid. By calculating the dynamical spin structure factor and the Raman scattering cross section, this thesis shows that there are salient signatures—qualitative and quantitative—of the Majorana fermions and the gauge fluxes emerging as effective degrees of freedom in the exactly solvable Kitaev honeycomb lattice model. The model is a representative of a class of spin liquids with Majorana fermions coupled to Z2 gauge fields. The qualitative features of the response functions should therefore be characteristic for this broad class of topological states.
Quantum mechanics. Quantumfield theory --- Electromagnetism. Ferromagnetism --- Thermal properties of solids --- Physics --- supergeleiding --- thermodynamica --- fysica --- magnetisme
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This thesis explores thermal transport in selected rare-earth-based intermetallic compounds to answer questions of great current interest. It also sheds light on the interplay of Kondo physics and Fermi surface changes. By performing thermal conductivity and electrical resistivity measurements at temperatures as low as 25mK, the author demonstrates that the Wiedemann–Franz law, a cornerstone of metal physics, is violated at precisely the magnetic-field-induced quantum critical point of the heavy-fermion metal YbRh2Si2. This first-ever observation of a violation has dramatic consequences, as it implies a breakdown of the quasiparticle picture. Utilizing an innovative technique to measure low-temperature thermal transport isothermally as a function of the magnetic field, the thesis interprets specific, partly newly discovered, high-field transitions in CeRu2Si2 and YbRh2Si2 as Lifshitz transitions related to a change in the Fermi surface. Lastly, by applying this new technique to thermal conductivity measurements of the skutterudite superconductor LaPt4Ge12, the thesis proves that the system is a conventional superconductor with a single energy gap. Thus, it refutes the widespread speculations about unconventional Cooper pairing in this material. .
Thermal properties of solids --- Physics --- Metals and their compounds --- Metallurgy --- supergeleiding --- thermodynamica --- fysica --- metalen
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This book explores critical phenomena in highly correlated quantum matter. Specifically, quantum antiferromagnets, magnon Bose condensates, and systems exhibiting deconfined quantum criticality are considered. The book’s main achievement is the incorporation of both quantum and statistical fluctuations into a quantum field theoretic treatment of critical phenomena. This yields significant new insights into an abundance of problems, positions them in a much more general context, and offers an unprecedented power to analyze experimental and numerical data and predict new effects. Further, a major result and overarching theme is the exploration of the scale-dependent coupling constant – an effect known in quantum chromodynamics as “asymptotic freedom.” The book provides the first analysis to reveal asymptotic freedom in the quantum magnetism context, and discusses many other manifestations. Another significant result concerns the development of a consistent theoretical framework that resolves a long-standing inconsistency in the theory of Bose condensation. Using the approach developed here, two new universality classes are subsequently identified. A final major result addresses the exotic scenario of deconfined quantum criticality. Within this framework, the book predicts the Bose condensation of particles with half-integer spin – the first- ever made in this regard. In closing, a smoking gun criterion to test for this exotic condensate is established. .
Quantum mechanics. Quantumfield theory --- Thermal properties of solids --- supergeleiding --- thermodynamica --- quantumfysica --- quantumtheorie --- fysica
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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.
Mathematical physics --- Quantum mechanics. Quantumfield theory --- Thermal properties of solids --- supergeleiding --- thermodynamica --- wiskunde --- fysica
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This thesis reports on the use of scanning tunnelling microscopy to elucidate the atomic-scale electronic structure of a charge density wave, revealing that it has a d-symmetry form factor, hitherto unobserved in nature. It then details the development of an entirely new class of scanned probe: the scanning Josephson tunnelling microscope. This scans the Josephson junction formed between a cuprate superconducting microscope tip and the surface of a cuprate sample, thereby imaging the superfluid density of the sample with nanometer resolution. This novel method is used to establish the existence of a spatially modulated superconducting condensate, something postulated theoretically over half a century ago but never previously observed.
Optics. Quantum optics --- Thermal properties of solids --- Theoretical spectroscopy. Spectroscopic techniques --- supergeleiding --- thermodynamica --- spectroscopie --- microscopie
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