scholarly journals Genuine Phase Diagram of Homogeneously Doped CuO2 Plane in High-Tc Cuprate Superconductors

2008 ◽  
Vol 77 (12) ◽  
pp. 124706 ◽  
Author(s):  
Hidekazu Mukuda ◽  
Yuhei Yamaguchi ◽  
Sunao Shimizu ◽  
Yoshio Kitaoka ◽  
Parasharam Shirage ◽  
...  
Keyword(s):  
Phase Diagram ◽  
Cuprate Superconductors ◽  
Cuo2 Plane ◽  
High Tc

scholarly journals Evolution of Charge-Lattice Dynamics across the Kuramoto Synchronization Phase Diagram of Quantum Tunneling Polarons in Cuprate Superconductors

2021 ◽  
Vol 6 (4) ◽  
pp. 52
Author(s):  
Victor Velasco ◽  
Marcello B. Silva Neto ◽  
Andrea Perali ◽  
Sandro Wimberger ◽  
Alan R. Bishop ◽  
...  
Keyword(s):  
Phase Diagram ◽  
Quantum Tunneling ◽  
Lattice Dynamics ◽  
Cuprate Superconductors ◽  
High Temperature Superconductivity ◽  
Phase Locking ◽  
Dynamic Structure ◽  
Cuo2 Plane ◽  
Kuramoto Model ◽  
Site Distribution

Because of its sensitivity to the instantaneous structure factor, S(Q,t = 0), Extended X-ray Absorption Fine Structure (EXAFS) is a powerful tool for probing the dynamic structure of condensed matter systems in which the charge and lattice dynamics are coupled. When applied to hole-doped cuprate superconductors, EXAFS has revealed the presence of internal quantum tunneling polarons (IQTPs). An IQTP arises in EXAFS as a two-site distribution for certain Cu–O pairs, which is also duplicated in inelastic scattering but not observed in standard diffraction measurements. The Cu–Sr pair distribution has been found to be highly anharmonic and strongly correlated to both the IQTPs and to superconductivity, as, for example, in YSr2Cu2.75Mo0.25O7.54(Tc=84 K). In order to describe such nontrivial, anharmonic charge-lattice dynamics, we have proposed a model Hamiltonian for a prototype six-atom cluster, in which two Cu-apical-O IQTPs are charge-transfer bridged through Cu atoms by an O atom in the CuO2 plane and are anharmonically coupled via a Sr atom. By applying an exact diagonalization procedure to this cluster, we have verified that our model indeed produces an intricate interplay between charge and lattice dynamics. Then, by using the Kuramoto model for the synchronization of coupled quantum oscillators, we have found a first-order phase transition for the IQTPs into a synchronized, phase-locked phase. Most importantly, we have shown that this transition results specifically from the anharmonicity. Finally, we have provided a phase diagram showing the onset of the phase-locking of IQTPs as a function of the charge-lattice and anharmonic couplings in our model. We have found that the charge, initially confined to the apical oxygens, is partially pumped into the CuO2 plane in the synchronized phase, which suggests a possible connection between the synchronized dynamic structure and high-temperature superconductivity (HTSC) in doped cuprates.

scholarly journals Phase Diagram of the Electron-Doped Cuprate Superconductors

2002 ◽  
Vol 71 (7) ◽  
pp. 1640-1643 ◽  
Author(s):  
Akito Kobayashi ◽  
Atsushi Tsuruta ◽  
Tamifusa Matsuura ◽  
Yoshihiro Kuroda
Keyword(s):  
Phase Diagram ◽  
Cuprate Superconductors

ENERGY BAND OVERLAPPING IN HIGH-Tc SUPERCONDUCTORS

1996 ◽  
Vol 10 (30) ◽  
pp. 1483-1490 ◽  
Author(s):  
M. MORENO ◽  
R. M. MÉNDEZ-MORENO ◽  
M. A. ORTIZ ◽  
S. OROZCO
Keyword(s):  
Weak Coupling ◽  
Cuprate Superconductors ◽  
Weak Coupling Limit ◽  
Band Model ◽  
Coupling Constant ◽  
High Tc Superconductors ◽  
Energy Bands ◽  
Effective Coupling ◽  
High Tc ◽  
Two Band Model

Multi-band superconductors are analyzed and the relevance of overlapping energy bands to the high-T c of these materials is studied. Within the BCS framework, a two band model with generalized Fermi surface topologies is developed. Values of the overlapped occupancy parameters for typical cuprate superconductors are obtained as a function of the ratio R and the effective coupling constant, λ, in the weak-coupling limit. The overlap scale is of the order or lower than the cutoff (Debye) energy. The typical behavior of the isotope effect is obtained. As these superconductors have transition temperatures above the phonon barrier, the results of this approach are important to the generic understanding of the high-T c superconducting mechanism.

scholarly journals EFFECTS OF c-AXIS HOPPING IN THE INTERLAYER TUNNELING MODEL OF HIGH-Tc LAYERED CUPRATES

1999 ◽  
Vol 13 (13) ◽  
pp. 1619-1632
Author(s):  
BIPLAB CHATTOPADHYAY ◽  
A. N. DAS
Keyword(s):  
Experimental Data ◽  
Transition Temperature ◽  
Cuprate Superconductors ◽  
Interlayer Coupling ◽  
Superconducting Gap ◽  
Tunneling Model ◽  
High Tc ◽  
Optimal Doping ◽  
Pair Tunneling ◽  
Layered Cuprates

We consider the interlayer pair-tunneling model for layered cuprates, including an effective single particle hopping along the c-axis. A phenomenological suppression of the c-axis hopping matrix element, by the pseudogap in cuprate superconductors, is incorporated. At optimal doping, quantities characteristic to the superconducting state, such as the transition temperature and the superconducting gap are calculated. Results from our calculations are consistent with the experimental observations with the noteworthy point that, the superconducting gap as a function of temperature shows excellent match to the experimental data. Predictions within the model, regarding T c variation with interlayer coupling, are natural outcomes which could be tested further.

Optical studies on the high Tc cuprate superconductors

1991 ◽  
Vol 43 (3) ◽  
pp. 4075
Author(s):  
Jiro Tanaka ◽  
Masaaki Shimizu ◽  
Koji Kamiya ◽  
Satoru Miyamoto ◽  
Yukio Tanaka
Keyword(s):  
Cuprate Superconductors ◽  
Optical Studies ◽  
High Tc

scholarly journals What is strange about high-temperature superconductivity in cuprates?

2017 ◽  
Vol 31 (25) ◽  
pp. 1745005
Author(s):  
I. Božović ◽  
X. He ◽  
J. Wu ◽  
A. T. Bollinger
Keyword(s):  
Phase Diagram ◽  
Cuprate Superconductors ◽  
High Temperature Superconductivity ◽  
Einstein Condensation ◽  
Strongly Correlated ◽  
Bose Einstein Condensation ◽  
Ultimate Question ◽  
Underdoped Cuprates ◽  
Bose Einstein ◽  
Superconducting Parameters

Cuprate superconductors exhibit many features, but the ultimate question is why the critical temperature ([Formula: see text]) is so high. The fundamental dichotomy is between the weak-pairing, Bardeen–Cooper–Schrieffer (BCS) scenario, and Bose–Einstein condensation (BEC) of strongly-bound pairs. While for underdoped cuprates it is hotly debated which of these pictures is appropriate, it is commonly believed that on the overdoped side strongly-correlated fermion physics evolves smoothly into the conventional BCS behavior. Here, we test this dogma by studying the dependence of key superconducting parameters on doping, temperature, and external fields, in thousands of cuprate samples. The findings do not conform to BCS predictions anywhere in the phase diagram.

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.

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