CRITICAL TEMPERATURE, ISOTOPE EFFECT AND SUPERCONDUCTING GAP IN THE MxLa2−xCuO4 AND M2RCu3O7−δ-TYPE SUPERCONDUCTORS

1988 ◽  
Vol 02 (06) ◽  
pp. 1415-1429 ◽  
Author(s):  
F. H. LIU ◽  
MARIAN APOSTOL
Keyword(s):  
Experimental Data ◽  
High Temperature ◽  
Critical Temperature ◽  
Isotope Effect ◽  
Fair Agreement ◽  
Superconducting Gap ◽  
Mechanism Of Superconductivity

The effect of the oxygen-displacive modes in the M x La 2−x CuO 4 and M 2 RCu 3 O 7−δ-type superconductors is discussed with regard to its possible relevance for a high-temperature mechanism of superconductivity. Critical temperature, isotope effect and superconducting gap are estimated in fair agreement with the experimental data.

The Isotope Effect Coefficient with Pseudogap and One-Band Superconductor

2016 ◽  
Vol 675-676 ◽  
pp. 23-26
Author(s):  
Thaipanya Chanpoom
Keyword(s):  
High Temperature ◽  
Critical Temperature ◽  
Isotope Effect ◽  
Temperature Region ◽  
High Temperature Superconductors ◽  
Superconducting Gap ◽  
Crossover Temperature ◽  
Critical Temperature Tc

This research studied the isotope effect coefficient of high temperature superconductors. The model used one-band superconductor which considered the competition of superconducting gap and pseudogap in the below crossover temperature region. The isotope effect coefficient is derived and approximation in simplify form. We find that the isotope effect coefficient is decreased as the critical temperature Tc and the crossover temperature T* ratio Tc/T* increased.

Effect of pseudogap and van Hove singularity density of state on the isotope effect coefficient of superconductor

2018 ◽  
Vol 32 (11) ◽  
pp. 1850130 ◽  
Author(s):  
Thaipanya Chanpoom
Keyword(s):  
Experimental Data ◽  
High Temperature ◽  
Critical Temperature ◽  
Isotope Effect ◽  
High Temperature Superconductors ◽  
Numerical Results ◽  
Density Of State ◽  
Van Hove Singularity

This research was to study the isotope effect coefficient of high temperature superconductors taking into account the pseudogap. We used the BCS-like model including the effect of the vHs density of state and pseudogap. The isotope effect coefficient was derived to the analytical and the approximation form. For the effect of vHs density of state, we found that the isotope effect coefficient increased as the critical temperature increased. For the pseudogap effect, as the critical temperature increased, the isotope effect coefficient decreased to the BCS value, 0.5. For the effect of the vHs density of state and pseudogap, we found that when the critical temperature increased, the isotope effect coefficient decreased. Finally, we showed our numerical results that can fit well with the experimental data of YBa[Formula: see text]La[Formula: see text]Cu3O[Formula: see text] and Y[Formula: see text]Pr[Formula: see text]Ba2Cu3O[Formula: see text] superconductors.

scholarly journals Standard Behaviour of Bi2Sr2CaCu2O8+δ Overdoped

2021 ◽  
Vol 6 (2) ◽  
pp. 13
Author(s):  
Giovanni Alberto Ummarino
Keyword(s):  
Experimental Data ◽  
Critical Temperature ◽  
Excellent Agreement ◽  
Free Parameter ◽  
Theoretical Calculations ◽  
Spin Fluctuations ◽  
Superconducting Gap ◽  
Eliashberg Theory ◽  
Antiferromagnetic Spin ◽  
D Wave

I calculated the critical temperature and superconducting gap in the framework of one band d wave Eliashberg theory with only one free parameter in order to reproduce the experimental data relative to Bi2Sr2CaCu2O8+δ(BSCCO) in the overdoped regime. The theoretical calculations are in excellent agreement with the experimental data and indicate that cuprates in the overdoped regime are well described by standard d-wave Eliashberg theory with coupling provided by antiferromagnetic spin fluctuations.

scholarly journals High-temperature superconductivity using a model of hydrogen bonds

2018 ◽  
Vol 115 (22) ◽  
pp. 5709-5713 ◽  
Author(s):  
Daniel Kaplan ◽  
Yoseph Imry
Keyword(s):  
High Temperature ◽  
Matrix Element ◽  
Simple Model ◽  
Hydrogen Bonds ◽  
Isotope Effect ◽  
High Temperature Superconductivity ◽  
High Temperature Superconductors ◽  
Superconducting Gap ◽  
Gap Equation ◽  
The Matrix

Recently, there has been much interest in high-temperature superconductors and more recently in hydrogen-based superconductors. This work offers a simple model that explains the behavior of the superconducting gap based on naive BCS (Bardeen–Cooper–Schrieffer) theory and reproduces most effects seen in experiments, including the isotope effect and Tc enhancement as a function of pressure. We show that this is due to a combination of the factors appearing in the gap equation: the matrix element between the proton states and the level splitting of the proton.

The investigation on anomalous isotope effect coefficient of LaSrCuO superconductor

2019 ◽  
Vol 33 (31) ◽  
pp. 1950379
Author(s):  
P. Mycharoen ◽  
P. Udomsamuthirun
Keyword(s):  
Experimental Data ◽  
Critical Temperature ◽  
Temperature Dependence ◽  
Isotope Effect ◽  
Weak Coupling ◽  
Numerical Results ◽  
Coupling Method ◽  
Density Of State ◽  
Van Hove Singularity ◽  
Weak Coupling Method

In this research, the anomalous isotope effect coefficient of LaSrCuO superconductor was investigated in the weak-coupling method. The constant and van Hove singularity density of state, pseudogap, and the form of pseudogap temperature dependence on critical temperature are included in our calculation. Finally, the numerical results are shown in comparison with the experimental data of LaSrCuO superconductor. We found that the van Hove singularity density of state and the inversely relation of pseudogap temperature and critical temperature can fit well with the anomalous isotope effect coefficient data of LaSrCuO superconductor.

PROPERTIES OF THE SUPERCONDUCTING GAP RATIO IN THE VAN HOVE SCENARIO OF HIGH-Tc OXIDES

2010 ◽  
Vol 24 (23) ◽  
pp. 2395-2401 ◽  
Author(s):  
A. BECHLAGHEM ◽  
D. BOURBIE
Keyword(s):  
Experimental Data ◽  
High Temperature ◽  
Low Temperature ◽  
Fermi Level ◽  
Qualitative Agreement ◽  
Superconducting Gap ◽  
Van Hove Singularity ◽  
High Tc ◽  
Gap Ratio ◽  
Van Hove Scenario

The superconducting gap ratio R = 2Δ(0)/kBTc has been studied in the context when the Fermi level is close to the van Hove singularity. In this approach, we consider the interaction is related to the phonons at low temperature but at high temperature, it is relevant to the magnetic excitations. Our results show that the superconducting gap ratio R takes large values in qualitative agreement with experimental data.

INFLUENCE OF THE ANTIFERROMAGNETIC CORRELATIONS ON THE CRITICAL TEMPERATURE OF THE HIGH TEMPERATURE SUPERCONDUCTORS

1991 ◽  
Vol 05 (17) ◽  
pp. 1161-1165 ◽  
Author(s):  
T. VERES ◽  
M. CRISAN
Keyword(s):  
Experimental Data ◽  
Nuclear Magnetic Resonance ◽  
High Temperature ◽  
Critical Temperature ◽  
High Temperature Superconductor ◽  
High Temperature Superconductors ◽  
Dynamic Susceptibility ◽  
Resonance Neutron ◽  
Antiferromagnetic Correlations ◽  
Good Agreement

The decreasing of the critical temperature of a high temperature superconductor due to the antiferromagnetic correlations and impurities has been calculated using a phenomenological model for the dynamic susceptibility considered in the explanations of the nuclear magnetic resonance, neutron scattering, tunneling experiments and the photoemission spectra. A good agreement with the experimental data has been obtained taking realistic values for the fit parameters.

ALLEGHENY STAINLESS TYPE 405

Alloy Digest ◽  
1985 ◽  
Vol 34 (7) ◽  
Keyword(s):  
Fracture Toughness ◽  
Corrosion Resistance ◽  
High Temperature ◽  
Critical Temperature ◽  
Physical Properties ◽  
Tensile Properties ◽  
Heat Treating ◽  
Ductile Material ◽  
Air Cooling ◽  
Temperature Performance

Abstract ALLEGHENY STAINLESS Type 405, unlike most other 12% chromium steels, is not subject to appreciable hardening through air cooling from high temperatures. This is an advantageous characteristic in those applications where a soft, ductile material is required after rapid cooling from above the critical temperature. The nonhardening tendency of Type 405 also retards the formation of hardening cracks where welding is employed. Its uses include annealing boxes and baffles where hardening during cooling would be undesirable. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties as well as fracture toughness. It also includes information on high temperature performance and corrosion resistance as well as heat treating and machining. Filing Code: SS-461. Producer or source: Allegheny Ludlum Corporation.

scholarly journals Evaluation on the Bond Capacity of the Fire-Protected FRP Bonded to Concrete Under High Temperature

2021 ◽  
Vol 15 (1) ◽  
Author(s):  
Soo-yeon Seo ◽  
Jong-wook Lim ◽  
Su-hyun Jeong
Keyword(s):  
High Temperature ◽  
Critical Temperature ◽  
Temperature Variation ◽  
Fire Resistance ◽  
Fire Protection ◽  
Element Analysis ◽  
External Temperature ◽  
Near Surface ◽  
Board Type ◽  
The Face

AbstractTo figure out the change in the reinforcing effect of FRP system used for the retrofit of RC beam when it is exposed to high temperature, it is required to evaluate not only the behavior of the entire beam, but also the bond performance at anchorage zone through a bond test according to the increase of external temperature. Moreover, the study to find various fire-protection methods is necessary to prevent the epoxy from reaching the critical temperature during an exposure to high temperature. In this manner, the fire-resistance performances of externally bonded (EB) FRP and near-surface-mounted (NSM) FRP to concrete block were evaluated by high-temperature exposure tests after performing a fire-protection on the surface in this paper. Board-type insulation with mortar was considered for the fire-protection of FRP system. After the fire-protection of the FRPs bonded to concrete blocks, an increasing exposure temperature was applied to the specimens with keeping a constant shear bond stress between concrete and the FRP. Based on the result, the temperature when the bond strength of the FRP disappears was evaluated. In addition, a finite element analysis was performed to find a proper method for predicting the temperature variation of the epoxy which is fire-protected with board-type insulation during the increase of external temperature. As a result of the test, despite the same fire-protection, NSM specimens were able to resist 1.54–2.08 times higher temperature than EB specimens. In the design of fire-protection of FRP system with the board-type insulation, it is necessary to consider the transfer from sides as well as the face with FRP. If there is no insulation of FP boards on the sides, the epoxy easily reaches its critical temperature by the heat penetrated to the sides, and increasing the thickness of the FP board alone for the face with FRP does not increase the fire-resistance capacity. As a result of the FE analysis, the temperature variation at epoxy can be predicted using the analytical approach with the proper thermal properties of FP mortar and board.

scholarly journals Cooper Pair-Like Systems at High Temperature and their Role on Fluctuations Near the Critical Temperature

1998 ◽  
Vol 12 (29n31) ◽  
pp. 3216-3219 ◽  
Author(s):  
M. Ausloos ◽  
S. Dorbolo
Keyword(s):  
Phase Transition ◽  
Electrical Resistivity ◽  
High Temperature ◽  
Critical Temperature ◽  
Oxygen Diffusion ◽  
Cooper Pair ◽  
Anomalous Behavior ◽  
Anomalous Effect ◽  
Linear Temperature ◽  
Ybco Sample

A logarithmic behavior is hidden in the linear temperature regime of the electrical resistivity R(T) of some YBCO sample below 2T c where "pairs" break apart, fluctuations occur and "a gap is opening". An anomalous effect also occurs near 200 K in the normal state Hall coefficient. In a simulation of oxygen diffusion in planar 123 YBCO, an anomalous behavior is found in the oxygen-vacancy motion near such a temperature. We claim that the behavior of the specific heat above and near the critical temperature should be reexamined in order to show the influence and implications of fluctuations and dimensionality on the nature of the phase transition and on the true onset temperature.

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