The Gap Symmetry and Fluctuations in High-Tc Superconductors


Book Description

Since the discovery in 1986 of high temperature superconductors by J. G. Bednorz and K. A. Müller, a considerable progress has been made and several important scientific problems have emerged. Within this NATO Advanced Study Institute our intention was to focus mainly on the controversial topic of the symmetry of the superconducting gap and given the very short coherence length, the role of fluctuations. The Institute on ‘The Gap Symmetry and Fluctuations in High- Superconductors’ took place in the “Institut d’Etudes Scientifiques de Cargèse” in Corsica, France, between 1 - 13 September 1997. The 110 participantsfrom 18 countries (yet 30 nationalities) including 23 full time lecturers, have spent two memorable weeks in this charming Mediterranean resort. All lecturers were asked to prepare pedagogical papers to clearly present the central physical idea behind specific model or experiment. The better understanding of physics of high temperature superconductivity is certainly needed to guide the development of applications of these materials in high and weak current devices.




Angle-Resolved Photoemission Spectroscopy Study of Spin Fluctuations in the Cuprate Superconductors


Book Description

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 applied the 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.







High-Tc Superconductors and Related Materials


Book Description

A broad introduction to high Tc superconductors, their parent compounds and related novel materials, covering both fundamental questions of modern solid state physics (such as correlation effects, fluctuations, unconventional symmetry of superconducting order parameter) and applied problems related to short coherence length, grain boundaries and thin films. The information that can be derived from electron spectroscopy and optical measurements is illustrated and explained in detail. Descriptions widely employ the clear, relatively simple, phenomenological Ginzburg-Landau model of complex phenomena, such as vortex physics, vortex charge determination, plasmons in superconductors, Cooper pair mass, and wetting of surfaces. The first comprehensive reviews of several novel classes of materials are presented, including borocarbides and chain cuprates.




Advances In Theoretical And Experimental Research Of High Temperature Cuprate Superconductivity


Book Description

This book is indexed in Chemical Abstracts ServiceResearchers working at the frontier of high-Tc Superconductors have reviewed the development in this area in the past 20 years. Both experimental and theoretical aspects have been covered. New directions and possible theoretical models were suggested. The contributors of this book are from China Center of Advanced Science and Technology (CCAST); Institute of Physics Chinese Academy of Sciences (CAS); National Lab for Superconductivity, Institute of Physics, CAS; School of Physics, Peking University and Center of Advanced Study Tsinghua University.This volume will be a useful guide to those who are working in the field.




Symmetry and Pairing in Superconductors


Book Description

These Proceedings of a NATO-ARW (HTECH ARW 97 1843) held at the Oreanda Hotel, Yalta, Ukraine from April 29 till May 2 , 1998 resulted from many discussions between various workers, concerning the need for a gathering of all (if possible) who were concerned with the subject of symmetry of the order parameter and pairing states for superconductivity. We applied ourselves in particular to High critical Temperature Superconductors (HTS), but also studied other unconventional superconductors. The study of HTS is one of the most prominent research subjects in solid state sciences. The understanding of the role of symmetry and pairing conditions are also thought to be necessary before technological applications since these features may be influenced by external fields. The workshop discussions have touched upon theoretical and experimental aspects, but also on related topics. These served as initiators for a very great amount of discussions with many comments from the audience. More than thirty "long lectures" and one on going "poster session" were held. Private discussions went unrecorded but obviously took place at many locations : lecture halls, staircases, cafes, bedrooms, bars, beach,bus, plane... Arguments openly reported for the first time were often quite sharp ones, -and this is an understatement.




Spectroscopy of High-Tc Superconductors


Book Description

Despite ten years of intensive research, many questions remain unanswered concerning the nature of the electronic structure (Fermi vs non-Fermi liquid) and mechanisms of superconductivity. Spectroscopy of High-Tc Superconductors, A Theoretical View provides a current, comprehensive review of the experimental results and theoretical interpretations concerning elementary excitation spectra (electronic, phononic, charge, and spin fluctuations) in high-Tc superconductors (HTSC). It discusses accepted microscopic models that describe the electronic structure of the copper-oxide plane - the three-band model, the generalized Emery model, the one-band Hubbard model, different kinds of the t-J model, and the regular Kondo-lattice model - and compares them with ARPES experiments. Leading Russian researchers also consider experimental results obtained by Raman scattering both by phonons and electronic excitations, including magnetic excitations in antiferromagnets in the normal phase, on almost all the types of superconducting cuprates. The results are treated theoretically with the emphasis on features thought to be related to superconductivity. The book also gives an account of the properties of the microwave surface impedance and complex conductivity as functions of temperature common for high-quality single crystals: YBCO, BSCCO, TBCCO, and BKBO. The basics of the muon method and a review of experimental results for superconducting states of different HTSC-compounds are also presented. By offering a thorough examination of current research in the field, this book will appeal to advanced students and researchers working in superconductivity and theoretical condensed matter physics.




High-Tc Superconductors Based on FeAs Compounds


Book Description

Physical properties and models of electronic structure are analyzed for a new class of high-TC superconductors which belong to iron-based layered compounds. Despite their variable chemical composition and differences in the crystal structure, these compounds possess similar physical characteristics, due to electron carriers in the FeAs layers and the interaction of these carriers with fluctuations of the magnetic order. A tremendous interest towards these materials is explained by the prospects of their practical use. In this monograph, a full picture of the formation of physical properties of these materials, in the context of existing theory models and electron structure studies, is given. The book is aimed at a broad circle of readers: physicists who study electronic properties of the FeAs compounds, chemists who synthesize them and specialists in the field of electronic structure calculations in solids. It is helpful not only to researchers active in the fields of superconductivity and magnetism, but also for graduate and postgraduate students and all those who would like to get acquaintained with this vivid area of the materials science.




The Physics of Superconductors


Book Description

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).




Superconductivity Centennial


Book Description

This book covers the important contributions of the Chinese during the development of high-temperature superconductors (HTS). The study of Y-based HTS, which was the first to be reported internationally at a liquid nitrogen temperature above 90 K, has retained the world record for superconducting transition temperatures. The book covers the study of superconducting energy gap, microscopic electron non-uniformity, ARPES research, 'kinks' research, eHigh-Tᶜ. In order to provide a comprehensive introduction to the physical properties of condensed matter, this book also includes studies on the thermodynamic properties of high-temperature superconductors, low-temperature heat transport, and Raman spectroscopy. In addition, this book includes important topics in theoretical studies, including the study of the magnetic and superconductivity of iron-based materials, the non-diagonal long procedure in condensed quantum phases, and the creation of oxygen sites in the CuO₂ plane. Rotational fluctuations lead to the study of superconducting states. This book is suitable for researchers and graduate students in condensed matter physics, materials science, optics and other fields.