SUPERCONDUCTIVITY AND TYPES OF GAP IN HIGH-Tc CUPRATES

2001 ◽  
Vol 15 (27) ◽  
pp. 3513-3528 ◽  
Author(s):  
FU-SUI LIU ◽  
WAN-FANG CHEN
Keyword(s):  
Phase Diagram ◽  
Long Range ◽  
Phase Coherence ◽  
Xy Model ◽  
Superconducting Gap ◽  
Band Model ◽  
High Tc ◽  
Local Spin ◽  
High Tc Cuprates

This paper extends the two-local-spin-mediated interaction from three- to four-band model, gives two T c formulas using long-range phase coherence condition in quantum and classical XY-models, phase diagram, and types of the gap in Bi 2 Sr 2 CaCu 2 O 8+δ (Bi2212). This paper argues that the superconducting gap and the pseudogap are the same gap just at different temperature regions. This paper also argues that the values of T c versus x should be determined by the long-range phase coherence conditions in the classical and quantum XY-model for underdoped and overdoped regions, respectively.

Mechanism of Pseudogap in High-Tc Cuprates

1998 ◽  
Vol 12 (29n31) ◽  
pp. 2935-2938
Author(s):  
Fu-Sui Liu
Keyword(s):  
Long Range ◽  
Cooper Pair ◽  
Phase Coherence ◽  
High Tc ◽  
Quasiparticle Excitation ◽  
High Tc Cuprates

This paper shows that the pseudogap (PG) of Y123 and B2212 is caused by two-local- Cu ++-spin-mediated interaction (TLSMI) in the CuO 2 plane and that PG is a gap of quasiparticle excitation which breaks a Cooper pair without long-range phase coherence.

Superconducting Gap and Pseudogap Behavior in High-Tc Cuprates

1999 ◽  
pp. 157-160
Author(s):  
M. Oda ◽  
H. Ishiguro ◽  
R. M. Dipasupil ◽  
N. Momono ◽  
T. Nakano ◽  
...  
Keyword(s):  
Superconducting Gap ◽  
High Tc ◽  
High Tc Cuprates

Electron-Doped Superconductivity in CuO2 Layered Compounds with Nd2CuO4− structure

1989 ◽  
Vol 156 ◽  
Author(s):  
H. Takagi ◽  
T. Ito ◽  
H. Matsubara ◽  
H. Watabe ◽  
T. Ido ◽  
...  
Keyword(s):  
Phase Diagram ◽  
Physical Properties ◽  
Transport Coefficients ◽  
Sharp Contrast ◽  
Layered Compounds ◽  
Hole Doping ◽  
High Tc ◽  
Electron Doping ◽  
High Tc Cuprates ◽  
Effect Of Doping

ABSTRACTWe have discovered 24 K-superconductivity in a family of compounds Ln2−xCexCuO4−y (Ln=Pr, Nd, Sm). Novel feature of the superconductivity in these family of compounds is that superconductivity is produced by electron-doping in sharp contrast with high-Tc cuprates discovered so far. The effect of doping on physical properties particularly the elecronic phase diagram and transport coefficients which indicate symmetry in many respects between electron- and hole- doping is described.

scholarly journals Are Superconductivity Mechanisms a Matter for Chemists?

2020 ◽  
Vol 5 (4) ◽  
pp. 67
Author(s):  
Michel Pouchard ◽  
Antoine Villesuzanne
Keyword(s):  
Fermi Level ◽  
Phonon Mode ◽  
Tight Binding ◽  
Superconducting Gap ◽  
Metallic State ◽  
Edge States ◽  
High Tc ◽  
Iron Selenide ◽  
Double Well Potential ◽  
High Tc Cuprates

From a tight-binding approach to the instability of nonbonding electronic states, along a double-well potential, we consider here how the coupling of these states with a phonon mode can open a superconducting gap at the Fermi level. The alternation of broken- and unbroken-symmetry states, along the phonon breathing distortion, induces the mixing of band-edge states on a very short timescale, according to the noncrossing rule of chemists. We show that this mixing may generate cationic and anionic disproportionation. The negative U mechanism is thus justified here, leading to the mixing of occupied and unoccupied pair states, for the opening of a 2Δ superconducting gap. The closeness of broad σ* and narrow π* bands in the vicinity of the Fermi level should favor the superconducting phase over the insulating or metallic state, in agreement with Micnas et al.’s studies. We applied this approach to several families of superconducting materials, i.e., doped strontium titanate, high-TC cuprates and iron selenide.

scholarly journals Implications of tunneling studies on high-Tc cuprates: superconducting gap and pseudogap

2001 ◽  
Vol 364-365 ◽  
pp. 475-479 ◽  
Author(s):  
N. Miyakawa ◽  
J.F. Zasadzinski ◽  
S. Oonuki ◽  
M. Asano ◽  
D. Henmi ◽  
...  
Keyword(s):  
Superconducting Gap ◽  
High Tc ◽  
High Tc Cuprates

Superconducting Gap in the Tunneling Spectra of High-Tc Cuprates

1998 ◽  
Vol 12 (29n31) ◽  
pp. 3179-3182
Author(s):  
M. Oda ◽  
K. Hoya ◽  
N. Abe ◽  
M. Yokoyama ◽  
N. Momono ◽  
...  
Keyword(s):  
Temperature Dependence ◽  
Doping Level ◽  
Mean Field ◽  
Superconducting Gap ◽  
High Tc ◽  
Spin Channel ◽  
The Mean ◽  
Carrier Doping ◽  
High Tc Cuprates ◽  
Doping Range

In Bi2212 and La214, the low-T(T ≪ T c ) superconducting gap magnitude 2Δ0 and the temperature dependence of in-plane resistivity ρ were examined over a wide carrier-doping range. In both systems, 2Δ0 increases with lowering doping level and ρ starts decreasing faster around a temperature T*, comparable to the mean-field T c or the onset temperature of a spin-channel singlet formation in the mean-field RVB thory, each of which is given by ~Δ0/2k B .

scholarly journals ON THE PHASE DIAGRAM OF HIGH TC CUPRATES

1992 ◽  
Vol 4 (2) ◽  
pp. 91-94,f2
Author(s):  
Hidetoshi FUKUYAMA
Keyword(s):  
Phase Diagram ◽  
High Tc ◽  
High Tc Cuprates
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