Download or read book Scanning Tunneling Spectroscopy Studies of High temperature Cuprate Superconductors written by Ching-Tzu Chen and published by . This book was released on 2006 with total page 334 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Advances in Theoretical and Experimental Research of High Tc Superconductivity written by Han Rushan and published by World Scientific Publishing Company. This book was released on 2019 with total page 512 pages. Available in PDF, EPUB and Kindle. Book excerpt: Researchers 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.

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 Scanning Tunneling Spectroscopy of Topological Insulators and Cuprate Superconductors written by Michael Manchun Yee and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Over the past twenty-five years, condensed matter physics has been developing materials with novel electronic characteristics for a wide range of future applications. Two research directions have shown particular promise: topological insulators, and high temperature copper based superconductors (cuprates). Topological insulators are a newly discovered class of materials that can be manipulated for spintronic or quantum computing devices. However there is a poor spectroscopic understanding of the current topological insulators and emerging topological insulator candidates. In cuprate superconductors, the challenge lies in raising the superconducting transition temperature to temperatures accessible in non-laboratory settings. This effort has been hampered by a poor understanding of the superconducting mechanism and its relationship with a mysterious pseudogap phase. In this thesis, I will describe experiments conducted on topological insulators and cuprate superconductors using scanning tunneling microscopy and spectroscopy, which provide nanoscale spectroscopic information in these materials.

Download or read book Tunneling Spectroscopy Studies of Superconductors written by Basu Dev Oli and published by . This book was released on 2021 with total page 201 pages. Available in PDF, EPUB and Kindle. Book excerpt: In multiband superconductors, different bands at the Fermi surface contribute to the superconductivity with different magnitudes of superconducting gaps on different portions of the Fermi surface. Each band in a multiband superconductor has a condensate with an amplitude and phase that weakly interacts with the other bands' condensate. The coupling strength between the bands determines whether one or two superconducting transition temperatures are observed, and it is the key to many peculiar properties. In general, if there are two gaps of different magnitude, there are two different length scales associated with the suppression of these gaps in applied magnetic fields, for example. Therefore, effects of multigap superconductivity can be observed in superconducting vortices, which are twirls of supercurrents that are generated when a superconductor is placed in a magnetic field. Furthermore, the two superconducting order parameters in different bands are characterized by a magnitude and phase. In multiband superconductors, there are collective excitations corresponding to fluctuations of the relative phase of two order parameters, so-called the Leggett mode. The first material identified as multiband superconductor is Magnesium Diboride (MgB2) in 2001 with a critical temperature Tc of 39 K. MgB2 is a superconducting material with the highest transition temperature among all conventional BCS superconductors. It has two superconducting gaps \Delta_\pi ~ 2 meV and \Delta_\sigma\ ~ 7 meV and they arise from the existence of two bands \pi and \sigma bands of boron electrons. The discovery of superconductivity in MgB2 renewed interest in the field of multiband superconductivity. MgB2 has attracted many scientists' attention both for the fundamental importance of understanding the multiband superconductivity and possible applications such as magnets, power cables, bolometers, Josephson junction-based electronic devices, and radio-frequency cavities. Afterward, other materials have been identified as multiband superconductors such as NbSe2, the family of iron-based superconductors, heavy fermion superconductors, multilayer cuprates, borocarbides, etc. This dissertation uses tunneling experiments to highlight multiband superconductivity features in two systems, namely MgB2 thin films and ultrathin films of Pb. Further, we use multiple techniques to study a superconducting material, nitrogen-doped niobium, used for superconducting radio-frequency cavities. For the project on MgB2, MgB2/Native-Oxide/Ag planar junctions are fabricated and characterized down to 2.1 K and in the magnetic field parallel to the sample surface up to 6 Tesla. This work investigates how pairbreaking affects the magnitude and phase of the order parameter in a multiband superconductor. The tunneling spectra are analyzed in the framework of a two-band model developed by our theory collaborator Prof. Alex Gurevich, Old Dominion University. The model allows the extraction of the pair-breaking parameters among other quantities. The analysis shows that the order parameter in the ? band is quickly suppressed in the field, the ? band is cleaner than the ? band. The ratio of pairbreaking parameter in the ? band to the ? band rapidly increases at fields higher than ~0.1 T and then plateau at higher fields. This transition around 0.1 T magnetic field suggests a phase decoupling in the two bands of MgB2. Below the transition, the two bands are phase-locked, so mostly, the superconductivity in the ? band is affected, and after phase decoupling, both bands are affected by the applied field. These results are important for a basic understanding of multiband superconductors and the application implications of this material. This phase decoupling has a new and profound consequence on the superconducting state of a multiband superconductor that has been theoretically predicted and never observed experimentally. For the Pb project, ultrathin films of Pb in ultrahigh vacuum conditions are deposited by e-beam evaporation and characterized with low-temperature scanning tunneling microscopy and spectroscopy (STM/STS). The STM/STS allows measuring the electronic density of states with the highest spatial resolution down to atomic scale. The shape of a superconducting vortex core is determined by the superconducting gap and the Fermi velocity, and the STM allows to map anisotropies of these quantities spatially. The vortex cores of Pb film show a complex shape that evolves from triangular at short distances from the center to a six-fold symmetric star shape farther away from the center. These details are very subtle, and they can be highlighted only if one works within the clean limit (to avoid the averaging effect of the scattering) and by fabricating the heterostructure that pins the vortices spatially. The complex vortex core shape reflects the anisotropy of the two bands that contribute to superconductivity in this material. For the project on Niobium, cold and hot spots from nitrogen-doped Nb cutouts are characterized by low temperature scanning tunneling microscopy and spectroscopy (STM/STS) combined with X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). The radiofrequency (RF) measurements of the quality factor and temperature mapping on an N-doped Nb superconducting resonator cavity are carried out at Jefferson Laboratory before cutting out the samples. This work aims to identify possible sources of excess dissipation in hot spots and relate them to the surface chemical composition and superconducting properties. The temperature mapping revealed a strong effect of the cavity cooldown rate on the intensities of hot spots and their spatial distribution, which indicates a significant contribution of trapped vortices to the RF dissipation. SEM images acquired on the cold and hot spots using a secondary electron detector show absence of residual hydride scars and niobium nitrides on their surface. Angle-resolved XPS measurements on the native surface of these samples revealed higher oxidized Nb 3d states on the N-doped Nb cold spots, which is supported by XPS depth profiles done on the samples by Argon ion sputtering. Argon ion sputtering of oxidized Nb removes oxygen preferentially from Nb2O5 and diffuses to bulk, thickening the lower oxidation state layers. The proximity theory framework's tunneling spectra analysis suggests hot spots have stronger pairbreaking due to a weakly reduced pair potential, a thicker metallic suboxide layer, and a wide distribution of the contact resistance. STM imaging of vortex cores shows a triangular vortex lattice in both samples, and the coherence length is nearly the same in hot and cold spots. The experimental data analysis suggests weakly degraded superconducting properties at the surface of hot spot regions are not the primary sources of RF losses. Instead, they are the regions where vortices nucleate first and get trapped during cooling down. These experimental techniques and findings will be crucial in helping to qualify new recipes for SRF cavity production and to boost their performance.

Download or read book Studies of High Temperature Superconductors written by A. V. Narlikar and published by Nova Science Publishers. This book was released on 1990 with total page 428 pages. Available in PDF, EPUB and Kindle. Book excerpt: CONTENTS: Weak Coupling Theory of High Temperature Superconductors; Investigations of a Few Novel Series of Thallium Cuprate Superconductors Showing Possible Change in the Sign of Charge Carriers with Composition; Some Structural & Chemical Aspects of the Bi-Pb-Sr-Ca-Cu-O System; High Magnetic Field Studies of High Temperature Superconductors; Fabrication of Bi-Sr-Ca-Cu Oxide Superconductors with Controlled Numbers of Cu-0 Layers; Characterization of High Temperature Superconductors by High Excitation Spectroscopies; Mossbauer Spectroscopy of High Temperature Superconductors; RVB & Related Theories of HTSC; Fabrication of 107k Superconducting Films & Their Normal State Transport Properties; Ion Beam Analysis of High T Superconductors; Thermal Conductivity of High Temperature Superconductor; A New Theoretical Approach to Electron Pairing And Uperconductivity in High T Superconductors; High Resolution Polarized X-Ray Absorption Spectroscopy: Symmetry of the Hole States in High-T Superconductors; Phase Diagrams in the Y-Ba-Cu-O System & Crystal Growth of Ybco Superconductors; Index.

Download or read book Advances In Theoretical And Experimental Research Of High Temperature Cuprate Superconductivity written by Rushan Han and published by World Scientific. This book was released on 2020-05-22 with total page 512 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Scanning Tunneling Spectroscopy Studies of Multiband and Unconventional Superconductivity written by Igor Fridman and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Pseudogap in High Temperature Superconductors written by A. V. Narlikar and published by Nova Biomedical Books. This book was released on 1999 with total page 244 pages. Available in PDF, EPUB and Kindle. Book excerpt: The present volume is devoted to the normal state pseudogap discovered in high Tc cuprates, which is currently an area of great topical interest and still not fully understood. The articles, written by the renowned experts in the field, consolidate the experimental findings and present various theoretical models to explain the occurrence of the gap.

Download or read book Scanning Tunneling Spectroscopy of Bi Based High Temperature Superconductors written by Craig Martin Howald and published by . This book was released on 2002 with total page 122 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Principles of Electron Tunneling Spectroscopy written by E. L. Wolf and published by Oxford University Press. This book was released on 2012 with total page 617 pages. Available in PDF, EPUB and Kindle. Book excerpt: Electron tunnelling spectroscopy as a research tool has strongly advanced understanding of superconductivity. This book explains the physics and instrumentation behind the advances illustrated in beautiful images of atoms, rings of atoms and exotic states in high temperature superconductors, and summarizes the state of knowledge that has resulted.

Download or read book Spectroscopic Studies of Superconductors written by and published by . This book was released on 1996 with total page 382 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Visualising the Charge and Cooper Pair Density Waves in Cuprates written by Stephen Edkins and published by Springer. This book was released on 2017-08-31 with total page 193 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Principles of Electron Tunneling Spectroscopy written by E. L. Wolf and published by International Monographs on Ph. This book was released on 2012 with total page 618 pages. Available in PDF, EPUB and Kindle. Book excerpt: Electron tunnelling spectroscopy as a research tool has strongly advanced understanding of superconductivity. This book explains the physics and instrumentation behind the advances illustrated in beautiful images of atoms, rings of atoms and exotic states in high temperature superconductors, and summarizes the state of knowledge that has resulted.

Download or read book The Investigation of Scanning Tunneling Microscopy and Spectroscopy on High Tc Superconductors written by Yi Yin and published by . This book was released on 2009 with total page 292 pages. Available in PDF, EPUB and Kindle. Book excerpt: Other work contributing to this thesis is focused on a cuprate superconductor, Bi 2- y Pb y Si 2 CuO 6+ [delta] . With the density of states (DOS) maps at both zero and nonzero magnetic fields, a division normalization method is applied to separate two characteristic energy scales. We extract a homogeneous hidden small gap coexisting with an apparent inhomogeneous gap. Compared with a recent experiment performed by Boyer et al. , the hidden small gap is believed to be a superconducting order and the apparent inhomogeneous gap is referred to the pseudogap phase. Under the magnetic field range in our experiment, a vortex liquid state is proposed. This technique can be extended to detect the possible superconducting information in the Nernst state above Tc .

Download or read book High Temperature Superconductors written by Ajay Kumar Saxena and published by Springer Science & Business Media. This book was released on 2012-07-10 with total page 266 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents the current knowledge about superconductivity in high Tc cuprate superconductors. There is a large scientific interest and great potential for technological applications. The book discusses all the aspects related to all families of cuprate superconductors discovered so far. Beginning with the phenomenon of superconductivity, the book covers: the structure of cuprate HTSCs, critical currents, flux pinning, synthesis of HTSCs, proximity effect and SQUIDs, possible applications of high Tc superconductors and theories of superconductivity. Though a high Tc theory is still awaited, this book describes the present scenario and BCS and RVB theories. The second edition was significantly extended by including film-substrate lattice matching and buffer layer considerations in thin film HTSCs, brick-wall microstructure in the epitaxial films, electronic structure of the CuO2 layer in cuprates, s-wave and d-wave coupling in HTSCs and possible scenarios of theories of high Tc superconductivity.

Download or read book Experimental Studies of the High temperature Superconducting Cuprates Using Thermal Difference Reflectance Spectroscopy written by Catherine Leigh Perry and published by . This book was released on 1996 with total page 242 pages. Available in PDF, EPUB and Kindle. Book excerpt: