Relaxation process in bismuth-based high-Tc superconductors in the range 100–200° C and its influence on resistive and superconducting properties

1992 ◽  
Vol 197 (3-4) ◽  
pp. 201-208 ◽  
Author(s):  
A.I. Romanenko ◽  
V.R. Valiakhmetov
1999 ◽  
Vol 13 (02) ◽  
pp. 59-69
Author(s):  
K. SUGAWARA ◽  
N. OHYA ◽  
N. ARAI ◽  
S. ICHIMURA ◽  
K. YAMAMOTO ◽  
...  

Several samples of K 3 C 60 have been made by the calcination of C 60 powder plus K flakes in evacuated quartz tubes at temperatures between 100°C and 700°C for 24 hours. The non-resonant microwave absorption (NRMA) measurements have been done below T c for these samples. From the linewidths and intensities of the NRMA signals, the superconducting properties (T c superconducting volume fraction and vortex size) have been studied as a function of the calcination temperature.


2019 ◽  
Vol 4 (2) ◽  
pp. 46 ◽  
Author(s):  
Andrzej M. Oleś ◽  
Krzysztof Wohlfeld ◽  
Giniyat Khaliullin

We discuss a few possibilities of high- T c superconductivity with more than one orbital symmetry contributing to the pairing. First, we show that the high energies of orbital excitations in various cuprates suggest a simplified model with a single orbital of x 2 − y 2 symmetry doped by holes. Next, several routes towards involving both e g orbital symmetries for doped holes are discussed: (i) some give superconductivity in a CuO 2 monolayer on Bi2212 superconductors, Sr 2 CuO 4 − δ , Ba 2 CuO 4 − δ , while (ii) others as nickelate heterostructures or Eu 2 − x Sr x NiO 4 , could in principle realize it as well. At low electron filling of Ru ions, spin-orbital entangled states of t 2 g symmetry contribute in Sr 2 RuO 4 . Finally, electrons with both t 2 g and e g orbital symmetries contribute to the superconducting properties and nematicity of Fe-based superconductors, pnictides or FeSe. Some of them provide examples of orbital-selective Cooper pairing.


2003 ◽  
Vol 17 (13) ◽  
pp. 2609-2622 ◽  
Author(s):  
N. Charoenthai ◽  
P. Winotai ◽  
R. Suryanarayanan ◽  
I. M. Tang

We report here on the structural and superconducting properties of RE 1 - 2x Pr x Ca x Sr 0.8 Ba 1.2 Cu 3 O 7 - δ (RE = Er and Gd, 0 ≤ x ≤ 0.2) high temperature superconductors. The transition temperature (Tc) of these compounds decreases when the Pr and Ca concentrations are increased. At constant Pr and Ca concentrations, the Tc of Er 1 - 2x Pr x Ca x Sr 0.8 Ba 1.2 Cu 3 O 7 - δ superconductor system is higher than that observed for the Gd 1 - 2x Pr x Ca x Sr 0.8 Ba 1.2 Cu 3 O 7 - δ system. For the Gd 0.8 Pr 0.1 Ca 0.1 Sr 0.8 Ba 1.2 Cu 3 O 7 - δ sample, after heating in argon followed by oxygen annealing, the orthorhombicity increases accompanied by 10 K increase in Tc. These results show that though our data indicate an ion-size effect, the Tc suppression rate dTc/dx depends very much on the heat treatment adopted to prepare the samples.


2004 ◽  
Vol 201 (9) ◽  
pp. 2082-2088 ◽  
Author(s):  
N. Charoenthai ◽  
P. Winotai ◽  
R. Suryanarayanan

JETP Letters ◽  
2010 ◽  
Vol 90 (10) ◽  
pp. 690-690
Author(s):  
E. P. Khlybov ◽  
O. E. Omelyanovsky ◽  
A. Zaleski ◽  
A. V. Sadakov ◽  
D. R. Gizatulin ◽  
...  

1989 ◽  
Vol 156 ◽  
Author(s):  
J. Darriet ◽  
J. A. Alonso ◽  
P. Burlet ◽  
B. Chevalier ◽  
B. Lepine ◽  
...  

ABSTRACTThe substituted oxides Bi2Sr2−xLaxCuO6+y and Bi2Sr2Ca1−xYxCu2O8+y isostructural to the n = 1 and n = 2 members of the high Tc superconductors have been prepared. The solid solution Bi2Sr2−xLaxCuO6+y shows a superconducting transition for 0.2–0.25<x<0.5 with an onset Tc near 30K and zero resistance temperatures which depend on x and the heat treatment. For x = 1 the isostructural phases Bi2ALaCuO6.5+y with A = Ca or Ba have also been synthesized and are not superconducting. A modelfor the localization of the oxygen atoms is proposed based on neutron diffraction of Bi2Sr1.6La0.4CuO6+y and Bi2CaLaCuO6+y.The Bi2Sr2Ca1−xYxCu2O8+y solid solution exhibits a superconducting transition for 0<x <0.7. The critical temperature remains almost constant (85–90K) for 0<x <0.3 and then decreases rapidly. The oxygen content value 8.65 for Bi2Sr2YCu2O8+y agrees well with the increase of the positive charge when calcium is replaced by yttrium.


1994 ◽  
Vol 2 (6) ◽  
pp. 401-410 ◽  
Author(s):  
J. Joo ◽  
J.P. Singh ◽  
T. Warzynski ◽  
A. Grow ◽  
R.B. Poeppel

2000 ◽  
Vol 337 (1-4) ◽  
pp. 327-330 ◽  
Author(s):  
A.I Romanenko ◽  
L.P Kozeeva ◽  
C Dong ◽  
F Zhou ◽  
F Wu ◽  
...  

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