Granular Aspects of High Tc Superconductivity

1990 ◽  
Vol 195 ◽  
Author(s):  
Guy Deutscher
Keyword(s):  
High Temperature ◽  
High Temperature Superconductivity ◽  
Original Publication ◽  
High Tc ◽  
High Tc Superconductivity ◽  
Bulk Ceramic ◽  
Ceramic Samples ◽  
Granular Superconductors

ABSTRACTAs Bednorz and Muller noted in their original publication reporting on the discovery of high temperature superconductivity, their oxides present many of the features of granular superconductors. This behavior was first primarily ascribed to poor connectivity of the grains in the bulk ceramic samples. but later studies have pointed out to more fundamental reasons for these similarities. We will discuss them after first reviewing the well established properties of low Tc granular superconductors.

scholarly journals Review on origin of the unusual high-Tc superconductivity in Ca1−xRExFe2As2 (RE = La, Ce, Pr, Nd)

2015 ◽  
Vol 1 (1) ◽  
Author(s):  
W. Zhou ◽  
Z. X. Shi
Keyword(s):  
High Temperature ◽  
Transition Temperature ◽  
Crystal Structures ◽  
High Temperature Superconductivity ◽  
Iron Pnictides ◽  
Iron Based Superconductors ◽  
High Tc ◽  
High Tc Superconductivity ◽  
Iron Based

AbstractSince the discovery of high temperature superconductivity in iron pnictides in 2008, many iron-based superconductors (IBSs) with various crystal structures have been exploited.Among them, superconductivity with the onset transition temperature T

HIGH Tc SUPERCONDUCTIVITY OF Sr-La-Cu-O AND Ba-Y-Cu-O THIN FILMS

1987 ◽  
Vol 01 (04) ◽  
pp. 177-180 ◽  
Author(s):  
B.R. ZHAO ◽  
L. LI ◽  
Y. LU ◽  
H.S. WANG ◽  
Y.H. SHI ◽  
...  
Keyword(s):  
Thin Films ◽  
High Temperature ◽  
Liquid Nitrogen ◽  
High Temperature Superconductivity ◽  
Oxide System ◽  
High Tc ◽  
High Tc Superconductivity ◽  
Short Time ◽  
Perovskite Type

In a very short time after it was reported1 that perovskite-type Ba-La-Cu oxide system could have high temperature superconductivity, many new results were reported.2,3 Later, Y was substituted for La to form Ba-Y-Cu oxides and the Tc rose to the liquid nitrogen region.4 In this report we describe the results obtained with the Sr-La-Cu-O and Ba-Y-Cu-O thin films.

Electron-Doped High Tc Superconductors

MRS Bulletin ◽  
1990 ◽  
Vol 15 (6) ◽  
pp. 60-67 ◽  
Author(s):  
M. Brian Maple
Keyword(s):  
High Temperature ◽  
High Temperature Superconductivity ◽  
High Temperature Superconductors ◽  
Building Blocks ◽  
The United States ◽  
Charge Carriers ◽  
Critical Temperatures ◽  
High Tc ◽  
Prevailing View ◽  
Identical Crystal

Since the discovery of high temperature superconductivity in layered copper-oxide compounds in the latter part of 1986, an enormous amount of research has been carried out on these remarkable materials. Prior to 1989, the prevailing view was that the charge carriers responsible for superconductivity in these materials were holes that move through conducting CuO2 planes. The CuO2 planes are the basic building blocks of the crystal structures of all the presently known oxides with superconducting critical temperatures Tc greater than ~30 K. Recently, new superconducting materials have been discovered in Japan and the United States in which the charge carriers involved in the superconductivity appear to be electrons, rather than holes, that reside within the conducting CuO2 planes. These findings could have important implications regarding viable theories of high temperature superconductivity as well as strategies for finding new high temperature superconductors.The new electron-doped materials have the chemical formula Ln2-xMxCuO4-y and exhibit superconductivity with superconducting critical temperatures Tc as high as ~25 K for x ≍ 0.15 and y ≍ 0.02. Superconductivity has been discovered for M = Ce and Ln = Pr, Nd, Sm, and Eu, and for M = Th and Ln = Pr, Nd, and Sm. A related compound with the identical crystal structure, Nd2CuO4-x-y Fx, has also been found to display superconductivity withTc ≍ 25 K. Recently, it has been observed that superconductivity with Tc ≍ 25 K can even be induced in nonsuperconducting Nd2-xCexCuO4-y compounds by substituting Ga or In for Cu. Thus, it appears that the CuO2 planes can be doped with electrons, rendering the Ln2CuO4-y parent compounds metallic and superconducting, by substituting electron donor elements at sites within, as well as outside, the CuO2 planes; i.e., by substituting (1) Ce4+ or Th4+ ions for Ln3+ ions; (2) F1- ions for O2- ions; and (3) Ga3+ or In3+ ions for Cu2+ ions.

HIGH Tc SUPERCONDUCTIVITY: A MODEL BASED ON ANTIFERROMAGNETIC FLUCTUATIONS

1987 ◽  
Vol 01 (03n04) ◽  
pp. 1089-1096
Author(s):  
D. Schmeltzer
Keyword(s):  
Free Energy ◽  
High Temperature ◽  
Low Temperature ◽  
Fermi Liquid ◽  
Antiferromagnetic Interaction ◽  
Two Dimensional ◽  
Fractional Statistics ◽  
Bose Statistic ◽  
High Tc ◽  
High Tc Superconductivity

The system X–La–Cu–O is described as a Fermi liquid with antiferromagnetic interaction. This interaction gives rise to two types of fluctuations, magnetic and superconducting. As a result, we find a free energy which contains two order parameters which at high temperature give rise to superconductivity and at low temperature to reentry-like paramagnetism. For two-dimensional systems, topological effects give rise to fractional statistics and as a result superconductivity appears when the topological angle θ gives rise to a Bose statistic.

Spinodal Decomposition and High-TC Superconductivity

1987 ◽  
Vol 99 ◽  
Author(s):  
Robert S. Markiewicz
Keyword(s):  
High Temperature ◽  
Spinodal Decomposition ◽  
Density Of States ◽  
Significant Contribution ◽  
Correlation Energy ◽  
High Temperature Superconductivity ◽  
Electron Exchange ◽  
Band Theory ◽  
High Tc ◽  
Lifshitz Point

ABSTRACTThe singularity in the density of states near a Lifshitz point makes a significant contribution to electron exchange and correlation energy, which does not show up in conventional band theory calculations. This paper discusses several consequences of this fact for high temperature superconductivity.

HIGH Tc STUDIES IN SVERDLOVSK

1988 ◽  
Vol 02 (06) ◽  
pp. 1331-1379 ◽  
Author(s):  
B. N. GOSHCHITSKII ◽  
V. L. KOZHEVNIKOV ◽  
M. V. SADOVSKII
Keyword(s):  
High Temperature ◽  
High Temperature Superconductivity ◽  
High Temperature Superconductors ◽  
Structural Phase ◽  
Nmr Relaxation ◽  
Structural Phase Transitions ◽  
High Tc ◽  
Review Reports ◽  
Academy Of Sciences

This review reports the main experimental results on superconducting lattice and electron properties of high-temperature superconductors of the type La 2−x Sr x CuO 4 and YBa 2 Cu 3 O 7 obtained at three institutes of the Ural Branch of the USSR Academy of Sciences in Sverdlovsk. Special attention is paid to investigations of structural phase transitions, heat capacity, optic and magnetic properties, NMR relaxation and the role of radiation disordering under the influence of fast neutron irradiation. In conclusion, a brief review of possible theories to explain high-temperature superconductivity in metal oxides is given.

Mesoscopic Structures and Their Effects on High-Tc Superconductivity

2017 ◽  
Author(s):  
H. Zhang
Keyword(s):  
High Temperature ◽  
Rock Salt ◽  
High Temperature Superconductors ◽  
Structural Features ◽  
X Ray Diffraction ◽  
Model Calculations ◽  
High Tc ◽  
High Tc Superconductivity ◽  
Electron Phonon Coupling ◽  
Structural Blocks

This article presents the results of model calculations carried out to determine the mesoscopic structural features of high-temperature superconducting (HTS) crystal structures, and especially their characteristic high critical temperature (Tc) and anisotropy. The crystal structure of high-temperature superconductors (HTSc) is unique in having some mesoscopic features. For example, the structures of a majority of cuprite superconductors are comprised of two structural blocks, perovskite and rock salt, stacked along the c-direction. This article calculates the interaction between the perovskite and rock salt blocks in the form of combinative energy in order to elucidate the effects of mesoscopic structures on high-Tc superconductivity. Both X-ray diffraction and Raman spectroscopy show that a ‘fixed triangle’ exists in the samples under investigation. The article also examines the importance of electron–phonon coupling in high-Tc superconductors.

THE ELECTRONIC STRUCTURE AND SUPERCONDUCTIVITY OF THE HIGH Tc COPPER OXIDES

1988 ◽  
Vol 02 (02) ◽  
pp. 167-180 ◽  
Author(s):  
M. SCHLUTER
Keyword(s):  
Electronic Structure ◽  
High Temperature ◽  
High Temperature Superconductivity ◽  
Copper Oxides ◽  
High Tc ◽  
Localized Orbital

The electronic structure and possible superconductivity mechanisms of the new high Tc copper oxides are discussed. The conventional band picture is contrasted with the localized orbital Mott-Hubbard picture for the electronic groundstate. The nature of quasiparticles introduced by doping of the insulating parent compounds depends on assumptions made for the underlying groundstate. Possible pairing mechanisms of these particles that have been proposed to lead to high temperature superconductivity are analyzed.

LA1BA2CU3O9-γ: Structural Analysis as Determined by Neutron Diffraction

1987 ◽  
Vol 99 ◽  
Author(s):  
J. P. Golben ◽  
YI Song ◽  
S. Chittipeddi ◽  
S. I. Lee ◽  
R. D. Mcmichael ◽  
...  
Keyword(s):  
High Temperature ◽  
Structural Analysis ◽  
Neutron Diffraction ◽  
Special Interest ◽  
Superconducting Phase ◽  
High Tc ◽  
High Tc Superconductivity ◽  
High Temperature Superconducting ◽  
Zero Resistance ◽  
Rule Out

The La-Ba-Cu-O system contains several phases of special interest in the field of high Tc superconductivity. Specifically intriguing is the La3−xBa3+xCu6O4+y (“3–3–6”) phase [1,2], the La1·8 5Ba·1 5CuO4 (‘K2NiF4’) phase with a zero resistance temperature (Tc) of about 20 K [3,4], and the La1Ba2CU3O9–6 (“1–2–3”) phase with Tc's reported up to 75 K [5–7]. It has been suggested that the “3–3–6” phase may also be superconducting, especially in a Ba-doped version such that the stoichiometry is 2–4–6 [8–10]. In addition to defining a new high temperature superconducting phase, this latter suggestion would also rule out the possibility of Cu-0 “chains” being important to 90 K superconductivity since these chains are absent in the proposed configuration [1,2] of this phase.

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