Transition temperature of strong-coupled superconductors reanalyzed

Allen, Philip B.; Dynes, R. C.

doi:10.1103/physrevb.12.905

Cited by 3,130 publications

(2,002 citation statements)

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“…This observation is connected with the observation that coupling at low frequency, which strongly enhances λ, has only a weak effect on T c . Carbotte and collaborators [16] argued that the product λω 1 (with ω 1 being the first moment as defined by Allen and Dynes [15]) is nearly proportional to T c for 1.2≤ λ ≤ 2.4; this quantity is proportional to the area under α 2 F and corresponds to a zone integral of γ Qν /ω Qν . They were not including strong coupling corrections to T c , [15] however, which were unknown at the time of the original work.…”

Section: Analysis and Summarymentioning

confidence: 99%

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Origin of strong coupling in lithium under pressure

Kasinathan

Koepernik

Kuneš

et al. 2007

Physica C: Superconductivity and its Applications

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In an attempt to provide a clearer understanding of the impressive increase in Tc under pressure in elemental Li, linear response calculation of the phonon dispersion curves, electron-phonon matrix elements, phonon linewidths and mode λ's have been carried out on a finer mesh (24 3 in the Brillouin zone) than done previously, for the volume corresponding to 20 GPa pressure. The result illustrates the great need for a fine mesh (even finer than this) for converged results of λ and the spectral function α 2 F . Although the initial pressure-induced transverse T1 phonon instability (in harmonic approximation) near the symmetry point K has dominated attention, the current results show that the high value of Tc gets strong contributions from elsewhere in the zone, particularly from the longitudinal mode along (100).

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Section: Analysis and Summarymentioning

confidence: 99%

“…One source of difference is the value ω ≈ 325 K (scaled from the P = 0 Debye frequency which is our calculated value of ω 1 . We have obtained T c using the Allen-Dynes equation [15] T…”

Section: Spectral Functions and T Cmentioning

confidence: 99%

Origin of strong coupling in lithium under pressure

Kasinathan

Koepernik

Kuneš

et al. 2007

Physica C: Superconductivity and its Applications

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“…We used the exchange-correlation energy functional of Perdew-Burke-Ernzerhof [9] in the generalized gradient approximation and employed the Vanderbilt ultrasoft pseudopotential [10]. We calculated the superconducting Tc using of the Allen-Dynes formula [11] and utilizing the effective screened Coulomb repulsion constant μ * = 0.1. We calculated the phonon frequencies by means of density-functional perturbation theory [12,13] on an 8 × 8 × 8 q-point grid for sc, sh, bcc, and hcp, an 8 × 8 × 2 q-point grid for IV, and a 4 × 4 × 4 q-point grid for cI16 using the QE code.…”

Section: Computational Detailsmentioning

confidence: 99%

First-principles study of phosphorus under high pressure: Crystal structure, superconductivity, and anharmonicity

Nakanishi

Ishikawa

Shimizu

2017

Proc. 17th Int. Conf. On High Pressure in Semiconductor Physics &Amp; Workshop on High-Pressure Study on Superconducting

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We have performed first-principles calculations of the structural stability, superconductivity, and anharmonicity of phosphorus under high pressure. The simple hexagonal (sh) structure transforms into an experimentally observed cI16 structure via a body-centered cubic (bcc) structure. In the transition from an sh into bcc structure, the superconducting critical temperature Tc increases from 0.5 K to 12 K, which is the highest Tc in phosphorus. It decreases to 6 K in the transition into the cI16 phase. The pressure-dependence of Tc is related to that of the density of states at the Fermi level. In addition, we investigated anharmonicities in phosphorus under high pressure.

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“…Generalizing the achieved result, Fig. 3 presents the complete dependence of the critical temperature on the Coulomb pseudopotential calculated on the basis of the classical expressions of Allen-Dynes and McMillan [42], [43]. It can be clearly seen that with the increase of µ ⋆ the critical temperature, based on classical formulas, more visibly differs from the strict result based on the Eliashberg equations.…”

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confidence: 95%