scholarly journals The Phenomenology of Iron Pnictides Superconductors Explained in the Framework of -Wave Three-Band Eliashberg Theory

2010 ◽  
Vol 2010 ◽  
pp. 1-6 ◽  
Author(s):  
G. A. Ummarino
Keyword(s):  
Critical Temperature ◽  
Order Parameter ◽  
Dominant Role ◽  
Coupling Constants ◽  
Iron Pnictides ◽  
Critical Temperatures ◽  
Sign Reversal ◽  
Eliashberg Theory ◽  
Wave Symmetry ◽  
Boson Coupling

Thes-wave three-band Eliashberg theory can simultaneously reproduce the experimental critical temperatures and the gap values of the superconducting materials , and as exponent of the more important families of iron pnictides. In this model the dominant role is played by interband interactions and the order parameter undergoes a sign reversal between hole and electron bands (-wave symmetry). The values of all the gaps (with the exact experimental critical temperature) can be obtained by using high values of the electron-boson coupling constants and small typical boson energies (in agreement with experiments).

scholarly journals Holographic superconductor with nonlinear Born–Infeld-type electrodynamics

2019 ◽  
Vol 34 (03n04) ◽  
pp. 1950019 ◽  
Author(s):  
S. I. Kruglov
Keyword(s):  
Critical Temperature ◽  
Order Parameter ◽  
Model Parameters ◽  
De Sitter ◽  
S Wave ◽  
Matching Method ◽  
Holographic Superconductor ◽  
Critical Temperatures ◽  
Sturm Liouville ◽  
Analytical Expressions

Holographic s-wave superconductors in the framework of nonlinear Born–Infeld-type electrodynamics are investigated in the background of Schwarzschild anti-de Sitter black holes. As particular cases, at some model parameters, we obtain results for Born–Infeld and exponential electrodynamics. We explore the analytical Sturm–Liouville eigenvalue problem in the probe limit where the scalar and electromagnetic fields do not affect the background metric. The critical temperatures of phase transitions and the order parameter are calculated which depend on the model parameters. We show that the critical exponent near the critical temperature is 1/2. Making use of the matching method, we derive analytical expressions for the condensation values and the critical temperature. The conductivity by the analytical method is calculated.

scholarly journals TEMPERATURE CHARACTERISTICS FOR PULSATION FREQUENCY IN GONIONEMUS

1928 ◽  
Vol 11 (5) ◽  
pp. 547-562 ◽  
Author(s):  
Ernst Wolf
Keyword(s):  
Critical Temperature ◽  
Functional Unit ◽  
Temperature Characteristic ◽  
Nerve Ring ◽  
Pulsation Frequency ◽  
Sense Organs ◽  
Critical Temperatures ◽  
Temperature Characteristics ◽  
System A ◽  
Definite Temperature

The frequency of contraction of the bell of Gonionemus was studied in relation to temperature, with intact animals and also where different operations were made on the nervous system. A number of values of µ are found for intact animals namely 8,100±, 10,500±, 32,000± and 22,500±, with critical temperatures at 9.6°, 12.3°, and 14.0°. Four different classes of operations were used: (1) Animals where the nerve ring was cut on two opposite sides of the bell; the µ values found are 10,500± and 21,300±, with a critical temperature at 13.4°. (2) Animals with four cuts through the nerve ring gave µ = 10,600 ± and µ = 21,000, with a critical temperature at 13.1°. (3) In animals where the bell was cut in half the temperature characteristic was found to be 16,900. And finally (4) in the animals where the nerve ring was totally removed µ values of 8,100, 16,000±, and 29,000 were found, with critical temperatures at 15.0° and 9.4°. These results are discussed from the standpoint of the theory which supposes that definite "temperature characteristics" may be associated with the functional activity of particular elements in a complex functional unit, and that these elements may be separately studied and identified by suitable experimental procedures involving the magnitudes of the respective temperature characteristics and the locations of associated critical temperatures. The swimming bell of medusæ with its marginal sense organs permits a fairly direct approach to such questions. It is found that even slight injuries to the marginal nerve ring, for example, produce specific modifications in the temperature relations which are different from those appearing when the organism is cut in half.

Crystalline-To-Amorphous Transformation of Intermetallic Compounds in the Zr-Fe-M System Induced by Irradiation

1994 ◽  
Vol 373 ◽  
Author(s):  
Arthur T. Motta ◽  
Lawrence M. Howe ◽  
Paul R. Okamoto
Keyword(s):  
Critical Temperature ◽  
Low Temperature ◽  
Dose Rate ◽  
Intermetallic Compounds ◽  
Electron Energy ◽  
Energy Dependence ◽  
Electron Irradiation ◽  
Critical Temperatures ◽  
Lower Critical Temperature ◽  
Ternary Intermetallic Compounds

AbstractThe binary and ternary intermetallic compounds Zr3Fe, Zr2 Fe, (Zr0.5,Nb0.5)3Fe, Zr3(Fe0.9,Ni0.1) and Zr3(Fe0.5,Ni0.5) were subjected to 900 keV electron irradiation until amorphous to study the change in the dose-to-amorphization with temperature. The critical temperatures were observed to vary with dose rate, and with the type of compound. Hexagonal (Zr0.5,Nb0.5)3Fe had an appreciably lower critical temperature and higher dose to amorphization at low temperature than orthorombic Zr3Fe, whereas other orthorombic Zr3(Fex,NiI-x) compounds were essentially identical in behavior to Zr3Fe. The electron energy dependence of the dose-to-amorphization was studied in Zr3Fe between 250 and 900 keV. The analysis of the results gives displacement energies of EZrd = 26 eV, EFed = 18 eV in the Zr3Fe compound.

CRITICAL ACTIVATION PARAMETERS FOR LaFeAsO-BASED SUPERCONDUCTORS

2011 ◽  
Vol 25 (30) ◽  
pp. 2299-2306
Author(s):  
ZOTIN KWANG-HUA CHU
Keyword(s):  
High Temperature ◽  
Transition Rate ◽  
High Temperature Superconductors ◽  
Activation Parameters ◽  
Iron Pnictides ◽  
Critical Temperatures ◽  
Superconducting Cuprates ◽  
Temperature Environment ◽  
Supersolid Helium ◽  
Very Low Temperature

The occurrence of high-Tc superconductivity in the iron pnictides shares a similar amorphous characteristic with that of high-Tc superconducting cuprates. Here we show that nearly frictionless (electric-field-driven) transport of condensed electrons in amorphous superconductors could happen after using the Eyring's transition-rate approach which has been successfully adopted to study the critical transport of other superconductors as well as supersolid helium in very low temperature environment. The critical temperatures related to the nearly frictionless transport of electrons were found to be directly relevant to the superconducting temperature of high-temperature superconductors (like La [ O 1-x F x] FeAs (x = 0.11-0.12)) after selecting specific activation energies and activation volumes.

scholarly journals The Intramolecular Pressure and the Extension of the Critical Point’s Influence Zone on the Order Parameter

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Jose Luis Rivera ◽  
Homero Nicanor-Guzman ◽  
Roberto Guerra-Gonzalez
Keyword(s):  
Transition Temperature ◽  
Critical Temperature ◽  
Liquid Phase ◽  
Order Parameter ◽  
Bulk Liquid ◽  
Influence Zone ◽  
Molecular Potential ◽  
Liquid Phases ◽  
Dynamics Simulations ◽  
Wide Zone

The critical point affects the coexistence behavior of the vapor-liquid equilibrium densities. The length of the critical influence zone is under debate because for some properties, like shear viscosity, the extension is only a few degrees, while for others, such as the density order parameter, the critical influence zone covers up to hundreds of degrees below the critical temperature. Here we show that, for ethane, the experimental critical influence zone covers a wide zone of tens of degrees (below the critical temperature) down to a transition temperature, at which the apparent critical influence zone vanishes, and the transition temperature can be predicted through a pressure analysis of the coexisting bulk liquid phase, using a simple molecular potential. The liquid phases within the apparent critical influence zone show low densities, making them behave internally like their corresponding vapor phases. Therefore, Molecular Dynamics simulations reveal that the experimentally observed wide extension of the critical influence zone is the result of a vapor-like effect due to low bulk liquid phase densities.

scholarly journals Strong correlation between electronic bonding network and critical temperature in hydrogen-based superconductors

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Francesco Belli ◽  
Trinidad Novoa ◽  
J. Contreras-García ◽  
Ion Errea
Keyword(s):  
Critical Temperature ◽  
Physical Properties ◽  
Fermi Level ◽  
Electronic Properties ◽  
Density Of States ◽  
Strong Correlation ◽  
Critical Temperatures ◽  
Structural And Electronic Properties ◽  
Superconducting Compounds ◽  
Better Than

AbstractBy analyzing structural and electronic properties of more than a hundred predicted hydrogen-based superconductors, we determine that the capacity of creating an electronic bonding network between localized units is key to enhance the critical temperature in hydrogen-based superconductors. We define a magnitude named as the networking value, which correlates with the predicted critical temperature better than any other descriptor analyzed thus far. By classifying the studied compounds according to their bonding nature, we observe that such correlation is bonding-type independent, showing a broad scope and generality. Furthermore, combining the networking value with the hydrogen fraction in the system and the hydrogen contribution to the density of states at the Fermi level, we can predict the critical temperature of hydrogen-based compounds with an accuracy of about 60 K. Such correlation is useful to screen new superconducting compounds and offers a deeper understating of the chemical and physical properties of hydrogen-based superconductors, while setting clear paths for chemically engineering their critical temperatures.

Thermodynamic of the charged AdS black holes in Rastall gravity: P − V critical and Joule–Thomson expansion

2020 ◽  
Vol 35 (14) ◽  
pp. 2050113
Author(s):  
Sen Guo ◽  
Yan Han ◽  
Guo Ping Li
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Critical Temperature ◽  
Critical Exponents ◽  
State Equation ◽  
The State ◽  
Thermodynamic Quantities ◽  
Critical Temperatures ◽  
Ads Black Holes ◽  
And Inversion

In this paper, we study the thermodynamic of the charged AdS black holes in Rastall gravity. Firstly, the thermodynamic quantities of the charged AdS black holes in Rastall gravity are reviewed and the state equation of this black hole is obtained. Then, we investigate the [Formula: see text] critical and the Joule–Thomson expansion of the charged AdS black holes in Rastall gravity in which the critical temperature and the critical exponents are obtained. In addition, we get the inversion temperature and plot the isenthalpic and inversion curves in the [Formula: see text] plane, and also determine the cooling-heating regions of this black hole through the Joule–Thomson expansion. Finally, we investigate the ratio between the minimum inversion and critical temperatures, and find that the Rastall constant [Formula: see text] does not affect of this ratio.

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