scholarly journals First-principles estimation of the superconducting transition temperature of a metallic hydrogen liquid

2021 ◽  
Vol 104 (18) ◽  
Author(s):  
Haoran Chen ◽  
Xiao-Wei Zhang ◽  
Xin-Zheng Li ◽  
Junren Shi
Keyword(s):  
Transition Temperature ◽  
First Principles ◽  
Superconducting Transition Temperature ◽  
Superconducting Transition ◽  
Metallic Hydrogen

Use of rescreened pseudopotentials for the superconductivity of aluminum at finite pressures

1981 ◽  
Vol 59 (3) ◽  
pp. 309-314 ◽  
Author(s):  
M. D. Whitmore
Keyword(s):  
Transition Temperature ◽  
Pressure Dependence ◽  
First Principles ◽  
Superconducting Transition Temperature ◽  
Imaginary Axis ◽  
Superconducting Transition ◽  
Volume Changes ◽  
Source Of Error ◽  
Coulomb Pseudopotential ◽  
Phonon Properties

Use is made of the pseudopotential determined by Dagens, Rasolt, and Taylor to calculate from first principles all the microscopic phonon and electron–phonon properties necessary for the superconducting transition temperature of aluminum, Tc, for zero pressure and for volume changes up to −10%. After fitting the Coulomb pseudopotential parameter μ* at zero pressure, Tc is calculated both by solving the Eliashberg gap equations on the imaginary axis, and by employing the approximate formulae of McMillan and of Leavens. The resulting pressure dependence of Tc is unsatisfactory. One source of error appears to be an insufficient pressure-induced shift of the phonon frequencies, indicating a limitation on the use of these pseudopotentials that is not widely appreciated. However, this is not believed to be the only difficulty and other possibilities are briefly discussed.

Theoretical Study of High Pressure Metallic Hydrogen

1990 ◽  
Vol 193 ◽  
Author(s):  
Troy W. Barbee ◽  
Alberto García ◽  
Marvin L. Cohen
Keyword(s):  
High Pressure ◽  
Phase Transitions ◽  
Transition Temperature ◽  
First Principles ◽  
Theoretical Study ◽  
Hexagonal Phase ◽  
Temperature Phase ◽  
Superconducting Transition ◽  
Zero Temperature ◽  
Metallic Hydrogen

ABSTRACTA study of the zero temperature phase transitions in hydrogen under megabar pressures using a first-principles total-energy method is presented. An anisotropic primitive hexagonal phase is found to be particularly stable relative to other monatomic phases for pressures between 4 and 8 megabars. Calculations of the vibrational frequencies show that this phase is unstable with respect to a distortion tripling the unit cell along the c-axis. Results for this distorted hexagonal phase will be presented, including a calculation of its superconducting transition temperature Tc.

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.

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