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.

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.

Structural phase transition in YBa2Cu3O7−δ: the role of dimensionality for high temperature superconductivity

1987 ◽  
Vol 63 (5) ◽  
pp. 385-388 ◽  
Author(s):  
Ivan K. Schuller ◽  
D.G. Hinks ◽  
M.A. Beno ◽  
D.W. Capone ◽  
L. Soderholm ◽  
...  
Keyword(s):  
Phase Transition ◽  
High Temperature ◽  
Structural Phase Transition ◽  
High Temperature Superconductivity ◽  
Structural Phase

scholarly journals Isotope Effect in the Translation-Invariant Bipolaron Theory of High-Temperature Superconductivity

2020 ◽  
Vol 5 (4) ◽  
pp. 80
Author(s):  
Victor D. Lakhno
Keyword(s):  
High Temperature ◽  
Isotope Effect ◽  
High Temperature Superconductivity ◽  
High Temperature Superconductors ◽  
Superconducting Transition ◽  
Strong Electron ◽  
Translation Invariant ◽  
Electron Phonon Interaction ◽  
Theory Of Superconductivity

It is shown that the translation-invariant bipolaron theory of superconductivity can explain the dependence of the isotope coefficient in high-temperature superconductors on the critical temperature of a superconducting transition: in the case of strong electron–phonon interaction, the isotope coefficient is low when doping is optimal and high when it is weak. It is demonstrated that in the case of London penetration depth, the absolute value of the isotope coefficient behaves in the opposite way. A conclusion of the great role of non-adiabaticity in the case of weak doping is made. The criteria for d-wave phonon input into the isotope effect is established.

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.

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