Download or read book Local Structure and Superconductivity in La sub 2 x Ba subscript X CuO4 for X written by and published by . This book was released on 1993 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt: This paper reviews our recent work on characterising the structural and electronic transitions in La{sub 2-x}Ba(subscript x)CuO4. This is a high-temperature superconductor which shows interesting an interesting interrelationship between structure and atomic properties. We have used x-ray and neutron diffraction to characterize the structure and show tat the current understanding of the structural phase transitions, and their relationship to the superconductivity, is incomplete.

Download or read book Superconductivity and Structure in La sub 2 x M subscript X CuO4 M written by and published by . This book was released on 2000 with total page 23 pages. Available in PDF, EPUB and Kindle. Book excerpt: The identification of charge stripes in La{sub 2-x-y}Nd{sub y}Sr(subscript x)CuO4 (Nd-214) has reenergized research on the original high transition temperature {Tc} superconductor, La{sub 2-x}Ba(subscript x)CuO4 (Ba-214), and related compounds. Early in the study of Ba-214, a low temperature phase transition was associated with changes in electrical properties. An apparent suppression of {Tc} near Ba x=0.125, was initially associated with a first order low temperature phase transformation. However, it was later shown that only very near Ba x=0.125 was {Tc} reduced markedly, and that the relationship between crystal structure and {Tc} is more complicated. This review well describe the low temperature crystal structures and microstructures, as well as the superconducting properties as determined from low field (1-100G) dc magnetometer measurements for Ba-214, Nd-214, and La{sub 2-x}Sr(subscript x)CuO4 (Sr-214). The authors will also describe some work in the related La{sub 2-x}Ca(subscript x)CuO4 (Ca-214). A basic knowledge of the interactions among superconductivity and low temperature phases will allow one to better understand the significance of the underlying charge stripe phases.

Download or read book Charge Stripes and Local Structural Inhomogeneities in La2 subscript X Sr Ba subscript X CuO4 High Temperature Superconductors written by Emil S. Bozin and published by . This book was released on 2003 with total page 536 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Suppression of Superconductivity in Orthorhombic La sub 2 x M subscript X CuO4 M written by and published by . This book was released on 1994 with total page 3 pages. Available in PDF, EPUB and Kindle. Book excerpt: We have extended the calcium solid-solubility limit in La{sub 2-x} Ca(subscript x)CuO4 to x = 0.2 using synthesis at high oxygen pressure. The superconducting transition temperature increases with doping to 34 K at x = 0.15 and is suppressed for x> 0.15, similar to the Sr-substituted material. At a fixed doping level, the optimum superconducting properties (the highest {Tc}) are found for flat and square CuO2planes.

Download or read book Superconductivity and Structure in La sub 2 x MxCuO4 M written by and published by . This book was released on 2000 with total page 23 pages. Available in PDF, EPUB and Kindle. Book excerpt: The identification of charge stripes in La{sub 2-x-y}Nd{sub y}SrxCuO4 (Nd-214) has reenergized research on the original high transition temperature {Tc} superconductor, La{sub 2-x}BaxCuO4 (Ba-214), and related compounds. Early in the study of Ba-214, a low temperature phase transition was associated with changes in electrical properties. An apparent suppression of {Tc} near Ba x=0.125, was initially associated with a first order low temperature phase transformation. However, it was later shown that only very near Ba x=0.125 was {Tc} reduced markedly, and that the relationship between crystal structure and {Tc} is more complicated. This review well describe the low temperature crystal structures and microstructures, as well as the superconducting properties as determined from low field (1-100G) dc magnetometer measurements for Ba-214, Nd-214, and La{sub 2-x}SrxCuO4 (Sr-214). The authors will also describe some work in the related La{sub 2-x}CaxCuO4 (Ca-214). A basic knowledge of the interactions among superconductivity and low temperature phases will allow one to better understand the significance of the underlying charge stripe phases.

Download or read book Crystal Growth And Characterization of the Model High Temperature Superconductor HgBa2CuO sub 4 delta written by and published by . This book was released on 2007 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: Since the discovery of high-transition-temperature (T{sub c}) superconductivity in La{sub 2-x}Ba(subscript x)CuO4 in 1986, the study of the lamellar copper oxides has remained at the forefront of condensed matter physics. Apart from their unusually high values of T{sub c}, these materials also exhibit a variety of complex phenomena and phases. This rich behavior is a consequence of the lamellar crystal structures, formed of copper-oxygen sheets separated by charge reservoir layers, and of the strong electron-electron correlations in the copper-oxygen sheets. After two decades of intensive research, which has stimulated many valuable new insights into correlated electron systems in general, there remains a lack of consensus regarding the correct theory for high-T{sub c} superconductivity. The ultimate technological goal of room-temperature superconductivity might only be attained after the development of a deeper understanding of the mercury-based compounds HgBa2Ca{sub n-1}Cu{sub n}OI{sub 2n+2+{delta}}, which currently exhibit the highest T{sub c}values. One very important issue in this regard is the role of electronic versus chemical and structural inhomogeneities in these materials, and the associated need to separate material-specific properties from those that are essential to superconductivity. Unfortunately, there has been remarkably little scientific work on the mercury-based compounds because sizable crystals have not been available; quantitative measurements of any kind would be invaluable benchmarks for testing the theories of high-T{sub c} superconductivity. The compounds HgBa2Ca{sub n-1}Cu{sub n}OI{sub 2n+2+{delta}} can be viewed as model systems not only because of their record high-T{sub c} values, but also because of their high-symmetry crystal structures. Of particular interest is the simplest member of this materials family, HgBa2CuO{sub 4+{delta}} (Hg1201), which possesses only one copper-oxygen sheet per unit cell (n = 1), as shown schematically in Figure 1a. The largest crystals obtained by previous growth methods do not exceed 1 mm3, and hence are insufficient in size for detailed studies by many experimental techniques. Here we report a novel recipe for the growth of Hg1201 crystals as well as detailed sample characterization results, including initial inelastic magnetic neutron scattering data. We note that samples grown by the method described here have already enabled recent optical conductivity, inelastic X-ray scattering, and angle-resolved photoemission studies.

Download or read book SUPERCONDUCTIVITY AND STRUCTURE IN LA 2 X M X CUO 4 M written by and published by . This book was released on 2000 with total page 23 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Synthesis Structure and Superconductivity of La sub 2 x K sub X CuO sub 4 written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Structural and superconducting properties of La[sub 2-x]K[sub x]CuO[sub 4] were studied by neutron and x-ray powder diffraction, ac magnetic susceptibility, and dc electrical resistivity. Superconductivity is observed in both orthorhombic and tetragonal phases with x[ge]0.06 and is absent for x[le]0.04. At room temperature, the system undergoes an orthorhombic-to-tetragonal phase transition at x[similar-to]0.07. Diffraction studies show no evidence of a low temperature tetragonal phase at 50 K. Comparison of these structural and superconducting properties with earlier data indicate that K contents have previously been highly overestimated.

Download or read book Linear Electron hole electron Pair Model of High temperature Superconductivity in La Sub 2 x M Sub X CuO Sub 4 and YBa Sub 2 Cu Sub 3 O Sub 7 y written by and published by . This book was released on 1989 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt: On the basis of the linear electron-hole-electron (e-h-e) pair model, we discuss how the number of holes (i.e., formal Cu{sup 3+} sites), and an applied pressure, affect the superconducting transition temperatures {Tc} of La{sub 2-x}M(subscript x)CuO4 and LBa2Cu3O{sub 7-y}(L = Y, Sm, Eu, Gd, Dy, Ho, Yb). We also examine the origin of the plateaus in the {Tc} vs oxygen content pilot of YBa2Cu3O{sub 7-y} within the framework of the linear e-h-e pair model. 17 refs.

Download or read book Theory of Copper Oxide Superconductors written by Hiroshi Kamimura and published by Springer. This book was released on 2010-10-14 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This is an advanced textbook for graduate students and researchers wishing to learn about high temperature superconductivity in copper oxides, in particular the Kamimura-Suwa (K-S) model. Because a number of models have been proposed since the discovery of high temperature superconductivity by Bednorz and Müller in 1986, the book first explains briefly the historical development that led to the K-S model. It then focuses on the physical background necessary to understand the K-S model and on the basic principles behind various physical phenomena such as electronic structures, electrical, thermal and optical properties, and the mechanism of high temperature superconductivity.

Download or read book Compilation of NRL Publications on High Temperature Superconductivity written by Donald U. Gubser and published by . This book was released on 1987 with total page 250 pages. Available in PDF, EPUB and Kindle. Book excerpt: Partial contents: Superconducting Phase Transitions in the La-M-Cu-O Layered Perovskite System, M = La, Ba Sr, and Pb; Temperature Dependent X-Ray Studies of the High T sub c Superconductor La(1.9)Ba(0.1)CuO4; X-Ray Identification of the Superconducting High T sub c Phase in the Y-Ba-Cu-O System; Processing and Properties of the High T sub c Superconducting Oxide Ceramic YBasub2Cu3O7; Phonon Density of States and Structure of the Superconductor YBasub2Cu3O7; Magnetic Field Studies of the La(2-x)MxCuO4 and Ba2Y1Cu3O7 High T sub c Superconductors; Preparation, Structure, and Magnetic Field Studies of High T sub c Superconductors; Electronic Structure, Bonding and Electron-Phonon Interaction in La-Ba-Cu-O Superconductors; Band Theory Analysis Of Anisotropic Transport in La2CuO4-Based Superconductors; Prediction of Anisotrophic Thermopower of La(2-x)MxCuO4; Character of States Near the Fermi Level in YBa2Cu3O7; Complex Hamiltonians: Common Features of Mechanisms of High-T sub c and Slow Relaxation; Plasma Sprayed Superconducting Oxide Coatings; Resonant Photoemission Study of Superconducting Y-Ba-Cu-O; Observed Trends in the X-Ray Photoelectron and Auger Spectra of High Temperature Superconductors; and Impact of High-Temperature Superconductors on High Power, Millimeter Wave Source Technology.

Download or read book The Relationship of Structure to Superconductivity in the Pr Ba Cu O System written by and published by . This book was released on 1994 with total page 75 pages. Available in PDF, EPUB and Kindle. Book excerpt: The relation of structure to lack of superconductivity in Pr-Ba-Cu-O was systematically investigated. First, the phase equilibria of this system was studied to find the processing parameters which maximize the cation-site ordering between Pr and Ba ions. Second, a comparative study between superconducting Nd-Ba-Cu-0 and non- superconducting Pr-Ba-Cu-0 was performed by forming solid-solution Nd- Pr-Ba-Cu-0. The relation between structure and superconductivity in Nd{sub 1-x}Pr(subscript x)Ba2Cu3O{sub 7-{delta}} is investigated. {Tc} decreases monotonically with increasing x and superconductivity disappears at around x=0.3-0.4. {Tc} is enhanced by 10K when the sample is processed at an oxygen partial pressure (PO2) of 0.01 atm, followed by oxygenation at 450C. Depression of {Tc} as a function of x and PO 2 is explained in terms of a charge-transfer model. It is suggested that destruction of superconductivity in the RE{sub 1-x}Pr(subscript x)Ba2CU3O{sub 7-{delta}} (RE=rare-earth) system can be viewed as disruption of four-fold planar coordinated Cu ions in the chain-site due to permanent occupation of extra Pr ions on Ba sites.

Download or read book Specific Heat of La Sub 2 x Sr Sub X CuO Sub 4 written by and published by . This book was released on 1990 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: Specific heat measurements on La{sub 1.85}Sr{sub 0.15}CuO4 show a linear correlation of the zero-field low-temperature linear term with the discontinuity at {Tc}, each of which provides a measure of the superconducting volume fraction. The correlation leads to an estimate of the normal-state density of electronic states which, together with the band structure calculated value, gives an electron-phonon interaction parameter that is too small to account for the superconductivity. For a sample with x=0.30 magnetic field insensitive anomaly in specific heat near 45K was observed which may be related to a structural phase transition. 10 refs., 3 figs., 1 tab.

Download or read book Phase Instability at the Maximum Tc in Oxide Superconductors written by and published by . This book was released on 1990 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: Observation of similar behavior in three different superconducting oxides suggests that the maximum {Tc} is limited by phase instability. These conclusions are based on previously published neutron powder diffraction data for La2CuO{sub 4+x} and Nd{sub 2-x}Ce(subscript x)CuO4 and new data for La{sub 2-x}Sr(subscript x)CuO4 which show a phase separated region for compositions adjacent to that which produces the highest {Tc}. 13 refs., 7 figs.

Download or read book Frontiers in Superconducting Materials written by Anant V. Narlikar and published by Springer Science & Business Media. This book was released on 2005-12-06 with total page 1122 pages. Available in PDF, EPUB and Kindle. Book excerpt: Frontiers in Superconducting Materials gives a state-of-the-art report of the most important topics of the current research in superconductive materials and related phenomena. It comprises 30 chapters written by renowned international experts in the field. It is of central interest to researchers and specialists in Physics and Materials Science, both in academic and industrial research, as well as advanced students. It also addresses electronic and electrical engineers. Even non-specialists interested in superconductivity might find some useful answers.

Download or read book Physics of Manganites written by T.A. Kaplan and published by Springer Science & Business Media. This book was released on 1999-05-31 with total page 299 pages. Available in PDF, EPUB and Kindle. Book excerpt: This series of books, which is published at the rate of about one per year, addresses fundamental problems in materials science. The contents cover a broad range of topics from small clusters of atoms to engineering materials and involves chemistry, physics, materials science and engineering, with length scales ranging from Ångstroms up to millimeters. The emphasis is on basic science rather than on applications. Each book focuses on a single area of current interest and brings together leading experts to give an up to date discussion of their work and the work of others. Each article contains enough references that the interested reader can access the relevant literature. Thanks are given to the Center for Fundamental Materials Research at Michigan State University for supporting this series. M. F. Thorpe, Series Editor E mail: thorpe@pa. msu. edu V PREFACE This book records invited lectures given at the workshop on Physics of Manganites, held at Michigan State University, July 26 29, 1998. Doped manganites are an interesting class of compounds that show both metal insulator and ferromagnetic to paramagnetic transitions at the same temperature. This was discovered in the early 1950s by Jonker and van Santen and basic theoretical ideas were developed by Zener (1951), Anderson and Hasegawa (1955), and deGennes (1960) to explain these transitions and related interesting observations.

Download or read book Introduction to Frustrated Magnetism written by Claudine Lacroix and published by Springer Science & Business Media. This book was released on 2011-01-12 with total page 682 pages. Available in PDF, EPUB and Kindle. Book excerpt: The field of highly frustrated magnetism has developed considerably and expanded over the last 15 years. Issuing from canonical geometric frustration of interactions, it now extends over other aspects with many degrees of freedom such as magneto-elastic couplings, orbital degrees of freedom, dilution effects, and electron doping. Its is thus shown here that the concept of frustration impacts on many other fields in physics than magnetism. This book represents a state-of-the-art review aimed at a broad audience with tutorial chapters and more topical ones, encompassing solid-state chemistry, experimental and theoretical physics.