Elastic behavior, pressure-induced doping and superconducting transition temperature of GdBa2Cu3O7-x

2021 ◽  
Author(s):  
Jared Omari Agora ◽  
Calford Otieno ◽  
P W O Nyawere ◽  
George S. Manyali
Keyword(s):  
Transition Temperature ◽  
Superconducting Transition Temperature ◽  
Density Functional ◽  
Local Density ◽  
Elastic Behavior ◽  
Bcs Theory ◽  
Hole Doping ◽  
Superconducting Transition ◽  
Generalized Gradient ◽  
Optimal Doping

Abstract Doping superconductors are known to vary the superconducting transition temperature TC depending on the degree of holes or electrons introduced in a system. In this study, we report how pressure-induced hole doping influences the TC of GdBa2Cu3O7-x superconducting perovskite. The study was carried out in the framework of density functional theory (DFT) using the Quantum espresso code. Ultrasoft pseudopotential with generalized gradient approximation (GGA) and local density approximation (LDA) functional was used to calculate the ground state energy using the plane waves (PW). The stability criterion was satisfied from the calculated elastic constants. The BCS theory and the Mc Millan’s equation was used to calculate the TC of the material at different conditions of pressure. The underdoped regime where the holes were less than those at optimal doping was found to be below 20 GPa of doping pressure. Optimal doping where the material achieved the highest TC (max) ~ 20 GPa of the doping pressure. Beyond the pressure of ~20 GPa was the over doping regime where a decrease in TC was recorded. The highest calculated TC (max) was ~141.16 K. The results suggest that pressure of ~20 GPa gave rise to the highest TC in the study.

Kinetic Energy Driven Charge Pairing and Superconductivity in the t–J Model

2003 ◽  
Vol 17 (22) ◽  
pp. 1151-1159
Author(s):  
Shiping Feng
Keyword(s):  
Transition Temperature ◽  
Kinetic Energy ◽  
Ground State ◽  
Qualitative Agreement ◽  
Superconducting Transition Temperature ◽  
Doping Concentration ◽  
Attractive Force ◽  
Hole Doping ◽  
Cooper Pairs ◽  
Superconducting Transition

The superconducting mechanism of doped cuprates is studied within the t–J model. It is shown that dressed holons interact directly through the kinetic energy by exchanging dressed spinon excitations. This interaction leads to a net attractive force between dressed holons, and the electron Cooper pairs originating from the dressed holon pairing state are due to the charge-spin recombination, and their condensation reveals the superconducting ground state. The superconducting transition temperature is determined by the dressed holon pair transition temperature, and is proportional to the hole doping concentration in the underdoped regime, in qualitative agreement with experiments.

Simulation of Structural Parameters and Superconducting Transition Temperature of MgB2 under Pressure

2005 ◽  
Vol 475-479 ◽  
pp. 3319-3322
Author(s):  
Yang Shao ◽  
X. Zhang ◽  
Fu Ling Tang
Keyword(s):  
Experimental Data ◽  
High Pressure ◽  
Transition Temperature ◽  
Superconducting Transition Temperature ◽  
Pressure Effect ◽  
Structural Parameters ◽  
Experimental Results ◽  
Bcs Theory ◽  
Superconducting Transition ◽  
Potential Parameters

We successfully developed the potential parameters for simulation of MgB2. With these potential parameters, we calculate the lattice parameters and volume variations with pressure up to 240GPa. All these results agree well with experimental data under 40GPa and provide reasonable tendencies from 40GPa to 240GPa. By employing the McMillan expression, it is found that the lattice stiffening dominants the behavior of Tc under pressure in the scope of BCS theory. Using our calculated Grüneisen parameter G g , the simulated pressure effect on Tc accords well with experimental results. Our result shows that the Tc of MgB2 can be destroyed by high pressure.

High Pressure Properties of Superconducting Material Palladium

2013 ◽  
Vol 813 ◽  
pp. 327-331
Author(s):  
Wei Min Peng ◽  
Zhong Li Liu ◽  
Hong Zhi Fu
Keyword(s):  
High Pressure ◽  
Perturbation Theory ◽  
Transition Temperature ◽  
Superconducting Transition Temperature ◽  
Density Functional ◽  
High Pressures ◽  
Ambient Pressure ◽  
Superconducting Transition ◽  
Superconducting Properties ◽  
Density Functional Perturbation Theory

The electronic and the superconducting properties of Pd were studied in the framework of density functional perturbation theory. We explored the superconducting transition temperature for bulk Pd and predicted possible superconductivity at ambient and high pressures. It is found that of Pd is 0.0356 K at ambient pressure and it decreases with pressure.

ELASTIC PROPERTIES OF La-BASED AND Y-BASED OXIDE SUPERCONDUCTIVE MATERIALS

1994 ◽  
Vol 08 (03) ◽  
pp. 275-307 ◽  
Author(s):  
WU TING ◽  
K. FOSSHEIM
Keyword(s):  
Phase Transitions ◽  
Transition Temperature ◽  
Elastic Properties ◽  
Superconducting Transition Temperature ◽  
Elastic Behavior ◽  
Superconducting Transition ◽  
Temperature Range ◽  
Elastic Anomalies ◽  
Structural Instabilities

Elastic measurements on La-based and Y-based bulk oxide superconductive materials in the temperature range 4.2–350 K are reviewed. Emphasis is placed on the elastic behavior near the superconducting transition temperature Tc and at higher temperatures where phase transitions or structural instabilities may occur. Possible mechanisms responsible for the observed elastic anomalies are discussed.

scholarly journals Reinforcing Increase of ΔTc in MgB2 Smart Meta-Superconductors by Adjusting the Concentration of Inhomogeneous Phases

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3066
Author(s):  
Yongbo Li ◽  
Guangyu Han ◽  
Hongyan Zou ◽  
Li Tang ◽  
Honggang Chen ◽  
...  
Keyword(s):  
Particle Size ◽  
Transition Temperature ◽  
Superconducting Transition Temperature ◽  
Doping Concentration ◽  
Raw Materials ◽  
Particle Sizes ◽  
Superconducting Transition ◽  
New Approach ◽  
Optimal Doping ◽  
Optimal Doping Concentration

Incorporating with inhomogeneous phases with high electroluminescence (EL) intensity to prepare smart meta-superconductors (SMSCs) is an effective method for increasing the superconducting transition temperature (Tc) and has been confirmed in both MgB2 and Bi(Pb)SrCaCuO systems. However, the increase of ΔTc (ΔTc = Tc ‒ Tcpure) has been quite small because of the low optimal concentrations of inhomogeneous phases. In this work, three kinds of MgB2 raw materials, namely, aMgB2, bMgB2, and cMgB2, were prepared with particle sizes decreasing in order. Inhomogeneous phases, Y2O3:Eu3+ and Y2O3:Eu3+/Ag, were also prepared and doped into MgB2 to study the influence of doping concentration on the ΔTc of MgB2 with different particle sizes. Results show that reducing the MgB2 particle size increases the optimal doping concentration of inhomogeneous phases, thereby increasing ΔTc. The optimal doping concentrations for aMgB2, bMgB2, and cMgB2 are 0.5%, 0.8%, and 1.2%, respectively. The corresponding ΔTc values are 0.4, 0.9, and 1.2 K, respectively. This work open a new approach to reinforcing increase of ΔTc in MgB2 SMSCs.

scholarly journals Asymmetric doping dependence of superconductivity between hole- and electron-doped triangular-lattice superconductors

2018 ◽  
Vol 32 (10) ◽  
pp. 1850122
Author(s):  
Yu Lan ◽  
Xixiao Ma ◽  
Ling Qin ◽  
Yongjun Wang ◽  
Shiping Feng
Keyword(s):  
Transition Temperature ◽  
Kinetic Energy ◽  
Triangular Lattice ◽  
Superconducting Transition Temperature ◽  
Narrow Range ◽  
Superconducting Transition ◽  
Optimal Doping ◽  
Doping Dependence ◽  
Wide Range ◽  
Doped Mott Insulator

Within the framework of kinetic-energy-driven superconductivity, the asymmetric doping dependence of superconductivity between the hole- and electron-doped triangular-lattice superconductors has been studied. It is shown that although the superconducting transition temperature has a dome-shaped doping dependence for both the hole- and electron-doped triangular-lattice superconductors, superconductivity appears over a wide range of doping in the hole-doped case, while it only exists in a narrow range of doping in the electron-doped case. Moreover, the maximum superconducting transition temperature around optimal doping in the electron-doped triangular-lattice superconductors is lower than that of the hole-doped counterparts. The theory also shows that the asymmetric doping dependence of superconductivity between the hole- and electron-doped cases may be a common feature for a doped Mott insulator.

scholarly journals Enhancing Superconductivity of the Nonmagnetic Quasiskutterudites by Atomic Disorder

Materials ◽  
2020 ◽  
Vol 13 (24) ◽  
pp. 5830
Author(s):  
Andrzej Ślebarski ◽  
Maciej M. Maśka
Keyword(s):  
High Temperature ◽  
Transition Temperature ◽  
Superconducting Transition Temperature ◽  
High Temperature Superconductors ◽  
Superconducting Phase ◽  
Length Scale ◽  
Superconducting Transition ◽  
Atomic Disorder ◽  
Strong Inhomogeneity ◽  
Related Compounds

We investigated the effect of enhancement of superconducting transition temperature Tc by nonmagnetic atom disorder in the series of filled skutterudite-related compounds (La3M4Sn13, Ca3Rh4Sn13, Y5Rh6Sn18, Lu5Rh6Sn18; M= Co, Ru, Rh), where the atomic disorder is generated by various defects or doping. We have shown that the disorder on the coherence length scale ξ in these nonmagnetic quasiskutterudite superconductors additionally generates a non-homogeneous, high-temperature superconducting phase with Tc⋆>Tc (dilute disorder scenario), while the strong fluctuations of stoichiometry due to increasing doping can rapidly increase the superconducting transition temperature of the sample even to the value of Tc⋆∼2Tc (dense disorder leading to strong inhomogeneity). This phenomenon seems to be characteristic of high-temperature superconductors and superconducting heavy fermions, and recently have received renewed attention. We experimentally documented the stronger lattice stiffening of the inhomogeneous superconducting phase Tc⋆ in respect to the bulk Tc one and proposed a model that explains the Tc⋆>Tc behavior in the series of nonmagnetic skutterudite-related compounds.

First principles calculations of structural, electronic and optical properties of InN compound

2015 ◽  
Vol 29 (05) ◽  
pp. 1550028 ◽  
Author(s):  
R. Graine ◽  
R. Chemam ◽  
F. Z. Gasmi ◽  
R. Nouri ◽  
H. Meradji ◽  
...  
Keyword(s):  
Optical Properties ◽  
Band Structure ◽  
Density Functional ◽  
Local Density ◽  
Indium Nitride ◽  
Alternative Form ◽  
Full Potential ◽  
Generalized Gradient ◽  
Pressure Derivative ◽  
Electronic And Optical Properties

We carried out ab initio calculations of structural, electronic and optical properties of Indium nitride ( InN ) compound in both zinc blende and wurtzite phases, using the full-potential linearized augmented plane wave method (FP-LAPW), within the framework of density functional theory (DFT). For the exchange and correlation potential, local density approximation (LDA) and generalized gradient approximation (GGA) were used. Moreover, the alternative form of GGA proposed by Engel and Vosko (EV-GGA) and modified Becke–Johnson schemes (mBJ) were also applied for band structure calculations. Ground state properties such as lattice parameter, bulk modulus and its pressure derivative are calculated. Results obtained for band structure of these compounds have been compared with experimental results as well as other first principle computations. Our results show good agreement with the available data. The calculated band structure shows a direct band gap Γ → Γ. In the optical properties section, several optical quantities are investigated; in particular we have deduced the interband transitions from the imaginary part of the dielectric function.

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