Download or read book Angle Resolved Photoemission Spectroscopy on Electronic Structure and Electron Phonon Coupling in Cuprate Superconductors written by and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In addition to the record high superconducting transition temperature (T{sub c}), high temperature cuprate superconductors are characterized by their unusual superconducting properties below T{sub c}, and anomalous normal state properties above T{sub c}. In the superconducting state, although it has long been realized that superconductivity still involves Cooper pairs, as in the traditional BCS theory, the experimentally determined d-wave pairing is different from the usual s-wave pairing found in conventional superconductors. The identification of the pairing mechanism in cuprate superconductors remains an outstanding issue. The normal state properties, particularly in the underdoped region, have been found to be at odd with conventional metals which is usually described by Fermi liquid theory; instead, the normal state at optimal doping fits better with the marginal Fermi liquid phenomenology. Most notable is the observation of the pseudogap state in the underdoped region above T{sub c}. As in other strongly correlated electrons systems, these unusual properties stem from the interplay between electronic, magnetic, lattice and orbital degrees of freedom. Understanding the microscopic process involved in these materials and the interaction of electrons with other entities is essential to understand the mechanism of high temperature superconductivity. Since the discovery of high-T{sub c} superconductivity in cuprates, angle-resolved photoemission spectroscopy (ARPES) has provided key experimental insights in revealing the electronic structure of high temperature superconductors. These include, among others, the earliest identification of dispersion and a large Fermi surface, an anisotropic superconducting gap suggestive of a d-wave order parameter, and an observation of the pseudogap in underdoped samples. In the mean time, this technique itself has experienced a dramatic improvement in its energy and momentum resolutions, leading to a series of new discoveries not thought possible only a decade ago. This revolution of the ARPES technique and its scientific impact result from dramatic advances in four essential components: instrumental resolution and efficiency, sample manipulation, high quality samples and well-matched scientific issues. The purpose of this treatise is to go through the prominent results obtained from ARPES on cuprate superconductors. Because there have been a number of recent reviews on the electronic structures of high-T{sub c} materials, we will mainly present the latest results not covered previously, with a special attention given on the electron-phonon interaction in cuprate superconductors. What has emerged is rich information about the anomalous electron-phonon interaction well beyond the traditional views of the subject. It exhibits strong doping, momentum and phonon symmetry dependence, and shows complex interplay with the strong electron-electron interaction in these materials. ARPES experiments have been instrumental in identifying the electronic structure, observing and detailing the electron-phonon mode coupling behavior, and mapping the doping evolution of the high-T{sub c} cuprates. The spectra evolve from the strongly coupled, polaronic spectra seen in underdoped cuprates to the Migdal-Eliashberg like spectra seen in the optimally and overdoped cuprates. In addition to the marked doping dependence, the cuprates exhibit pronounced anisotropy with direction in the Brillouin zone: sharp quasiparticles along the nodal direction that broaden significantly in the anti-nodal region of the underdoped cuprates, an anisotropic electron-phonon coupling vertex for particular modes identified in the optimal and overdoped compounds, and preferential scattering across the two parallel pieces of Fermi surface in the antinodal region for all doping levels. This also contributes to the pseudogap effect. To the extent that the Migdal-Eliashberg picture applies, the spectra of the cuprates bear resemblance to that seen in established strongly coupled electron-phonon superconductors such as Pb. On the other hand, the cuprates deviate from this conventional picture. In the underdoped regime, the carriers are best understood as small polarons in an antiferromagnetic, highly electron correlated background, while the doped compounds require an anisotropic electron-phonon vertex to detail the prominent mode coupling signatures in the superconducting state. Electronic vertex corrections to the electron-phonon coupling furthermore may enhance, and for certain phonons, determine, the anisotropy of the electron-phonon coupling. A consistent picture emerges of the cuprates, combining strong, anisotropic electron-phonon coupling, particular phonon modes that could give rise to such a coupling, and an electron-electron interaction modifying the el-ph vertex.

Download or read book Handbook of High Temperature Superconductivity written by J. Robert Schrieffer and published by Springer Science & Business Media. This book was released on 2007-03-20 with total page 627 pages. Available in PDF, EPUB and Kindle. Book excerpt: Since the 1980s, a general theme in the study of high-temperature superconductors has been to test the BCS theory and its predictions against new data. At the same time, this process has engendered new physics, new materials, and new theoretical frameworks. Remarkable advances have occurred in sample quality and in single crystals, in hole and electron doping in the development of sister compounds with lower transition temperatures, and in instruments to probe structure and dynamics. Handbook of High-Temperature Superconductvity is a comprehensive and in-depth treatment of both experimental and theoretical methodologies by the the world's top leaders in the field. The Editor, Nobel Laureate J. Robert Schrieffer, and Associate Editor James S. Brooks, have produced a unified, coherent work providing a global view of high-temperature superconductivity covering the materials, the relationships with heavy-fermion and organic systems, and the many formidable challenges that remain.

Download or read book Very High Resolution Photoelectron Spectroscopy written by Stephan Hüfner and published by Springer Science & Business Media. This book was released on 2007-02-09 with total page 411 pages. Available in PDF, EPUB and Kindle. Book excerpt: Photoemission spectroscopy is one of the most extensively used methods to study the electronic structure of atoms, molecules, and solids and their surfaces. This volume introduces and surveys the field at highest energy and momentum resolutions allowing for a new range of applications, in particular for studies of high temperature superconductors.

Download or read book Angle Resolved Photoemission Spectroscopy on High Temperature Superconductors written by Junfeng He and published by Springer. This book was released on 2016-06-21 with total page 137 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book mainly focuses on the study of the high-temperature superconductor Bi2Sr2CaCu2O8+δ (Bi2212) and single-layer FeSe film grown on SrTiO3 (STO) substrate by means of angle-resolved photoemission spectroscopy (ARPES). It provides the first electronic evidence for the origin of the anomalous high-temperature superconductivity in single-layer FeSe grown on SrTiO3 substrate. Two coexisted sharp-mode couplings have been identified in superconducting Bi2212. The first ARPES study on single-layer FeSe/STO films has provided key insights into the electronic origin of superconductivity in this system. A phase diagram and electronic indication of high Tc and insulator to superconductor crossover have been established in the single-layer FeSe/STO films. Readers will find essential information on the techniques used and interesting physical phenomena observed by ARPES.

Download or read book High Resolution Angle resolved Photoemission Study of Hightemperature Superconductors written by and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The latest development of angle-resolved photoemission spectroscopy (ARPES) technique has seen extremely high energy resolution and momentum resolution, as well as multiple angle detection. These advancements have led to new findings through efficient Fermi surface mapping, fine electronic structure resolving, and direct determination of electron self-energy. In this paper, we will highlight some recent high resolution ARPES work on high temperature superconductors. These include: (1) charge-ordering and evolution of electronic structure with doping; (2) bilayer splitting and Fermi surface topology of Bi2212; and (3) strong electron phonon coupling and electron electron interaction in high temperature superconductors.

Download or read book Photoemission Spectroscopy on High Temperature Superconductor written by Wentao Zhang and published by Springer Science & Business Media. This book was released on 2012-08-22 with total page 147 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book mainly focuses on the study of the high-temperature superconductor Bi2Sr2CaCu2O8 by vacuum, ultra-violet, laser-based, angle-resolved photoemission spectroscopy (ARPES). A new form of electron coupling has been identified in Bi2212, which occurs in the superconducting state. For the first time, the Bogoliubov quasiparticle dispersion with a clear band back-bending has been observed with two peaks in the momentum distribution curve in the superconducting state at a low temperature. Readers will find useful information about the technique of angle-resolved photoemission and the study of high-temperature superconductors using this technique. Dr. Wentao Zhang received his PhD from the Institute of Physics at the Chinese Academy of Sciences.

Download or read book Angle resolved Photoemission Spectroscopy Studies of the Mott Insulator to Superconductor Evolution in Ca2x Na subscript xCuO2Cl2 written by Kyle Michael Shen and published by Ann Arbor, Mich. : University Microfilms International. This book was released on 2005 with total page 514 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Angle Resolved Photoemission Spectroscopy Study of Spin Fluctuations in the Cuprate Superconductors written by Francisco Restrepo and published by Springer Nature. This book was released on 2022-09-13 with total page 113 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Electron phonon Interaction And Lattice Dynamics In High Tc Superconductors written by Han Zhang and published by World Scientific. This book was released on 2020-02-13 with total page 358 pages. Available in PDF, EPUB and Kindle. Book excerpt: Understanding the mechanism of the high-temperature superconductors has been a very important topic in condensed matter physics. Researchers have been trying to explain the role of electron-phonon interaction (EPI) in cuprates. Some important properties of the cuprates could not be explained by conventional BCS theory. This book contains the experimental and theoretical studies on the EPI. The experimental part covers the results of angle-resolved photoemission spectroscopy (ARPES), isotopic effect, elastic neutron scattering study of electron-phonon, lattice role and so on. The theoretical part covers the electron-phonon, polaron and bipolaron, effect of lattice, fine structure in the tunnelling spectra of electron-doped cuprates, identification of the bulk pairing symmetry in high-temperature superconductors.Students and researchers interested in high-temperature superconductors, especially the EPI in cuprates will find this title very useful.

Download or read book Low Energy Excitations in Cuprate High Temperature Superconductors written by Inna Vishik and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The mechanism of superconductivity in the cuprate high temperature superconductors is an enduring problem in condensed matter physics, and a detailed experimental phenomenology is a crucial starting point for microscopic understanding. Angle-resolved photoemission spectroscopy (ARPES) measures electronic structure in momentum-space. Low-energy excitations in the cuprates, including the superconducting gap, are known to be anisotropic in momentum space, so the momentum resolution afforded by ARPES is key to understanding the physics and uncovering the mechanism. In this dissertation, I present experiments which pursue the cuprate superconductivity problem from several angles: understanding electron-boson coupling which may be involved in mediating superconductivity (Chapters 6 and 7 and Appendix B), understanding the momentum-space structure of the normal state pseudogap (Chapter 5 and Appendix A), understanding how superconductivity coexists with the pseudogap and other phases (Chapters 3 and 4). Much of this work took advantage of a recent development in ARPES technology, using a UV laser as a light source, which allows experiments to be performed with superior energy and momentum resolution. These experiments highlight the wealth of information that is available in ARPES data, including dispersions, scattering rates, and spectral gaps, and they demonstrate the importance of exploring these variables comprehensively as a function of temperature, doping, and momentum.

Download or read book Angle resolved Photoemission Studies of Two dimensional Electron Systems written by Yang Liu and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation examines the electronic properties of 2D electron systems, including ultrathin metallic films grown on semiconductor substrates and graphite/graphene layers. Both systems are (quasi) two-dimensional and are of particular interest due to their technological importance. The major experimental tool is angle-resolved photoemission spectroscopy, which can directly measure the spectral function of the quasiparticle. The study of ultrathin metallic films focuses on the substrate effect on the electronic structure of the film. Thin metallic films can support quantum well states, which are essentially electronic standing waves. Our work on Ag films grown on Ge(111) demonstrates that the incommensurate interface potential results in strong modifications to quantum well states. The observed electronic interference structures are attributable to the mixing of electronic standing waves by the Ag-Ge interface potential. The complex Fermi surface, as a result of this interface scattering, can affect the electronic transport properties. An even stronger modification of quantum well states can be observed when the metal films are grown on stepped substrates. More specifically, our study of corrugated Ag/Pb films grown on Si(557)-Au surface reveals multiple sets of quantum well states that are centered at the Brillouin zone boundaries corresponding to the step modulation. This indicates that the valence electrons form coherent grating cavity modes which are defined by the corrugation geometry. Graphitic materials, made of sheets of carbon atomic layers, have unusual electronic structures known as Dirac cones. Our photoemission measurements of graphite/graphene layers reveal unexpected gaps at normal emission, one at ~67 meV and another much weaker one at ~150 meV. The major gap features persist up to room temperature, and diminish with increasing emission angles. We show that these gaps arise from electronic coupling to out-of-plane and in-plane vibrational modes at the point, respectively, in accordance with conservation laws and selection rules governed by quantum mechanics. Our study suggests a new approach for characterizing phonons and electron-phonon coupling in solids.

Download or read book High Temperature Cuprate Superconductors written by Nikolay Plakida and published by Springer Science & Business Media. This book was released on 2010-08-26 with total page 570 pages. Available in PDF, EPUB and Kindle. Book excerpt: High-Temperature Cuprate Superconductors provides an up-to-date and comprehensive review of the properties of these fascinating materials. The essential properties of high-temperature cuprate superconductors are reviewed on the background of their theoretical interpretation. The experimental results for structural, magnetic, thermal, electric, optical and lattice properties of various cuprate superconductors are presented with respect to relevant theoretical models. A critical comparison of various theoretical models involving strong electron correlations, antiferromagnetic spin fluctuations, phonons and excitons provides a background for understanding of the mechanism of high-temperature superconductivity. Recent achievements in their applications are also reviewed. A large number of illustrations and tables gives valuable information for specialists. A text-book level presentation with formulation of a general theory of strong-coupling superconductivity will help students and researches to consolidate their knowledge of this remarkable class of materials.

Download or read book Electron Spectroscopy Study of Bscco High temperature Superconductors written by Edward Ratner and published by . This book was released on 1996 with total page 216 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Spectroscopic Studies of Superconductors written by and published by . This book was released on 1996 with total page 380 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Angle resolved Photoemission Spectroscopy ARPES Studies of Cuprate Superconductors written by and published by . This book was released on 2010 with total page 109 pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation is comprised of three different angle-resolved photoemission spectroscopy (ARPES) studies on cuprate superconductors. The first study compares the band structure from two different single layer cuprates Tl2Ba2CuO6+[delta] (Tl2201) Tc, max ~95 K and (Bi1.35Pb0.85)(Sr1.47La0.38)CuO6+[delta] (Bi2201) Tc, max 35 K. The aim of the study was to provide some insight into the reasons why single layer cuprate's maximum transition temperatures are so different. The study found two major di erences in the band structure. First, the Fermi surface segments close to ([pi],0) are more parallel in Tl2201 than in Bi2201. Second, the shadow band usually related to crystal structure is only present in Bi2201, but absent in higher Tc Tl2201. The second study looks at the different ways of doping Bi2Sr2CaCu2O8+[delta] (Bi2212) in-situ by only changing the post bake-out vacuum conditions and temperature. The aim of the study is to systematically look into the generally overlooked experimental conditions that change the doping of a cleaved sample in ultra high vacuum (UHV) experiments. The study found two major experimental facts. First, in inadequate UHV conditions the carrier concentration of Bi2212 increases with time, due to the absorption of oxygen from CO2/CO molecules, prime contaminants present in UHV systems. Second, in a very clean UHV system at elevated temperatures (above about 200 K), the carrier concentration decreases due to the loss of oxygen atoms from the Bi-O layer. The final study probed the particle-hole symmetry of the pseudogap phase in high temperature superconducting cuprates by looking at the thermally excited bands above the Fermi level. The data showed a particle-hole symmetric pseudogap which symmetrically closes away from the nested FS before the node. The data is consistent with a charge density wave (CDW) origin of the pseudogap, similar to STM checkerboard patterns in the pseudogap state.

Download or read book Photoemission Studies of High Temperature Superconductors written by David W. Lynch and published by Cambridge University Press. This book was released on 1999-05-28 with total page 446 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book describes important topics in high-temperature superconductivity; for graduate students and researchers.

Download or read book Angle Resolved Photoelectron Spectroscopy Studies of the Many Body Effects in the Electronic Structure of High Tc Cuprates written by and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In spite of the failures to find an ultimate theory of unconventional superconductivity, after many years of research the scientific community possesses a considerable store of theoretical knowledge about the problem. Over time, the focus is gradually shifted from finding a theoretical description of an experimentally observed phenomenon to distinguishing between multiple models that offer comparably reasonable descriptions. From the point of view of an experimentalist, this means that any qualitative under-standing of an experimental observation would no longer suffice. Instead, the empha-sis in the experimental research should be shifted to accurate quantification of obser-vations, which becomes possible only if the results available from all the available ex-perimental methods are connected together by the theoretical glue. Among the meth-ods that are to be unified, ARPES plays a central role. The reason for this is that it gives access to the single-particle excitation spectrum of the material as a function of both momentum and energy with very high resolution. Other experimental techniques, such as inelastic neutron scattering (INS), Raman spectroscopy, or the newly estab-lished Fourier-transform scanning tunneling spectroscopy (FT-STS) probe more com-plicated two-particle spectra of the electrons and up to now can not achieve the mo-mentum resolution comparable with that of ARPES. Such reasoning serves as the mo-tivation for the present work, in which some steps are done towards understanding the anomalous effects observed in the single-particle excitation spectra of cuprates and relating the ARPES technique to other experimental methods. First, the electronic properties of BSCCO are considered -- the superconducting cuprate most studied by surface-sensitive methods. The recent progress in un-derstanding the electronic structure of this material is reported, focusing mainly on the many-body effects (renormalization) and their manifestation in the ARPES spectra.