Role of silver addition on mechanical and superconducting properties of high-Tc superconductors

1994 ◽  
Vol 2 (6) ◽  
pp. 401-410 ◽  
Author(s):  
J. Joo ◽  
J.P. Singh ◽  
T. Warzynski ◽  
A. Grow ◽  
R.B. Poeppel
Keyword(s):  
Superconducting Properties ◽  
High Tc Superconductors ◽  
Silver Addition ◽  
High Tc

THE VAN HOVE SINGULARITY IN HIGH Tc SUPERCONDUCTORS

1995 ◽  
Vol 09 (09) ◽  
pp. 1067-1080 ◽  
Author(s):  
M.L. HORBACH ◽  
H. KAJÜTER
Keyword(s):  
Energy Scale ◽  
Measured Temperature ◽  
Van Hove Singularity ◽  
High Tc Superconductors ◽  
Electronic Density ◽  
High Tc ◽  
Scattering Rate ◽  
Weakly Coupled ◽  
Coherence Lengths

Experimental indications for the role of the van Hove singularity (vHs) in the electronic density of states of high Tc superconductors are discussed. It is argued that (i) like the resistivity, the measured temperature and doping dependences of the normal state electronic specific heat of YBCO are consistent with the existence of a vHs and (ii) the doping dependence of Tc in the underdoped and optimally doped regimes may be accounted for mainly by a vHs. Further, we discuss the suppression of the quasiparticle scattering rate below Tc, and the coherence lengths in the hole-doped materials and NCCO. Assuming that the same mechanism for superconductivity operates in the electron-doped and the hole-doped cuprates, we argue that the bosonic mode that causes the superconductivity is strongly influenced by the doping in the overdoped regime. We further argue that this boson involves an energy scale larger than that of phonons and is only weakly coupled to the charge carriers.

APPLICATION OF ESR TO HIGH-Tc SUPERCONDUCTORS AND RELATED MATERIALS IV: ALKALI K DOPING EFFECTS ON THE SUPERCONDUCTING CHARACTERISTICS OF K3C60

1999 ◽  
Vol 13 (02) ◽  
pp. 59-69
Author(s):  
K. SUGAWARA ◽  
N. OHYA ◽  
N. ARAI ◽  
S. ICHIMURA ◽  
K. YAMAMOTO ◽  
...  
Keyword(s):  
Microwave Absorption ◽  
Calcination Temperature ◽  
Volume Fraction ◽  
Superconducting Properties ◽  
High Tc Superconductors ◽  
High Tc ◽  
Doping Effects ◽  
Superconducting Volume Fraction ◽  
Vortex Size ◽  
Quartz Tubes

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.

scholarly journals Orbital Symmetry and Orbital Excitations in High-Tc Superconductors

2019 ◽  
Vol 4 (2) ◽  
pp. 46 ◽  
Author(s):  
Andrzej M. Oleś ◽  
Krzysztof Wohlfeld ◽  
Giniyat Khaliullin
Keyword(s):  
Simplified Model ◽  
Entangled States ◽  
Cooper Pairing ◽  
Superconducting Properties ◽  
High Tc Superconductors ◽  
Orbital Symmetry ◽  
Spin Orbital ◽  
High Tc ◽  
High Energies

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.

Role of Cu in high Tc superconductors: A photoemission study

1988 ◽  
Vol 153-155 ◽  
pp. 153-154 ◽  
Author(s):  
P. Sen ◽  
B. Dauth ◽  
T. Kachel ◽  
B. Rupp ◽  
W. Gudat
Keyword(s):  
High Tc Superconductors ◽  
High Tc ◽  
Photoemission Study

Structural and Superconducting Properties of RE1 - 2xPrxCaxSr0.8Ba1.2Cu3O7 - δ (RE = Er and Gd) High Tc Superconductors

2003 ◽  
Vol 17 (13) ◽  
pp. 2609-2622 ◽  
Author(s):  
N. Charoenthai ◽  
P. Winotai ◽  
R. Suryanarayanan ◽  
I. M. Tang
Keyword(s):  
Heat Treatment ◽  
High Temperature ◽  
Transition Temperature ◽  
Size Effect ◽  
High Temperature Superconductors ◽  
Superconducting Properties ◽  
High Tc Superconductors ◽  
High Tc ◽  
Oxygen Annealing ◽  
Ion Size

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.

CHARGE CARRIER MASS IN HIGH Tc SUPERCONDUCTORS

1999 ◽  
Vol 13 (29n31) ◽  
pp. 3582-3584
Author(s):  
MARCO ZOLI
Keyword(s):  
Charge Carrier ◽  
Numerical Study ◽  
Small Polaron ◽  
Electron Mass ◽  
High Tc Superconductors ◽  
High Tc ◽  
Effective Masses ◽  
Polaron Theory ◽  
Holstein Model

The theory of polarons has experienced a surge of activity in the last years partly due to the possible role of polaronic quasiparticles in high Tc superconductors. This numerical study of the Holstein model shows that the polaronic effective masses become essentially dimension independent and of order ≃10–50 times the electron mass at sufficiently strong intermolecular coupling forces. Such values (which are much lower than those obtained by traditional small polaron theory) would erase one the serious objections against a (bi)polaronic picture for high Tc superconductors.

DESCRIPTION OF THE Tl, Pb and Bi CUPRATE HIGH-Tc SUPERCONDUCTORS AS INTERCALATION COMPOUNDS

1989 ◽  
Vol 03 (09) ◽  
pp. 723-728 ◽  
Author(s):  
R.S. MARKIEWICZ ◽  
B.C. GIESSEN
Keyword(s):  
Electron Transfer ◽  
Charge Transfer ◽  
Intercalation Compounds ◽  
Acceptor Site ◽  
High Tc Superconductors ◽  
High Tc ◽  
Stage Number ◽  
Graphite Intercalation ◽  
Superconducting Oxides

Treating the new superconducting oxides as intercalation compounds, especially, as analogues to graphite intercalation compounds (GIC), clarifies the understanding of a number of their properties; in this description, the ratio of the number of cuprate layers per intercalant unit is equivalent to the stage number in GIC’s. In particular, the role of charge transfer (presumably, electron transfer from oxygen in the [Formula: see text] sheets to an acceptor site located in the intercalant) in optimizing Tc can be well discussed in these terms, leading to the prediction that the curve of Tc versus n, the number of [Formula: see text] layers, must have a maximum at a specific value of n.

Structural and superconducting properties of Y1-2xPrxCaxBa2Cu3O7-?: high-Tc superconductors

2004 ◽  
Vol 201 (9) ◽  
pp. 2082-2088 ◽  
Author(s):  
N. Charoenthai ◽  
P. Winotai ◽  
R. Suryanarayanan
Keyword(s):  
Superconducting Properties ◽  
High Tc Superconductors ◽  
High Tc
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