Evidence for Effective Weakening of Electron-Phonon Interaction in Superconducting Tantalum, Niobium, Lead and Aluminum

Zheng, X. H.; Walmsley, D.G.

doi:10.1007/s10909-013-0887-5

Cited by 6 publications

(25 citation statements)

References 29 publications

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“…5 tells us how much the potential well has to be deepened in aluminium and lead in the normal state. See [21] to appreciate how much it has to be deepened in niobium and tantalum.…”

Section: Discussionmentioning

confidence: 99%

“…Keeping this in mind we have devised an electron-pairing rule in the BCS theory that allows a consistent pseudopotential to describe the electron-phonon interaction in both the normal and superconducting states [21].…”

Section: Discussionmentioning

confidence: 99%

“…for electron relaxation time in metals that leads through the Drude formula to ρ(T ), x = ν/k B T [21] with k B being the Boltzmann constant. Eq.…”

Section: Electrical Resistivitymentioning

confidence: 99%

“…We find δV = −2.193 Ry and r 1 = 0.395a in Eq. (10) In a previous publication [21] we first applied the Gaussian potential in Eq. (10) to pilot inversion (δV = −2.414 in Fermi energy and r 1 = 0.381a) and then refined the potential on 26 nodes between r = 0 and 2.45a (radius of the 12th atomic shell), compared with the current values δV = −2.193 in Fermi energy and r 1 = 0.395a.…”

Section: Resistivity Inversionmentioning

confidence: 99%

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Comparison of Heine–Abarenkov and alternative pseudopotentials for electron–phonon interaction in aluminium, lead, lithium and calcium

Zheng

Walmsley

2017

Solid State Communications

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Applying the Heine-Abarenkov pseudopotential to aluminium and lead in both the superconducting and normal states, Carbotte and coworkers have set a challenging standard befitting the status of the classic BCS superconductor theory. Upholding the same standard and equipped with the technique of numerical inversion, we have extracted alternative pseudopotentials from experimental data with minimal prejudgement that might cloud the physics. The two potentials are broadly consistent in the superconducting state but distinctly different in the normal state. This is an urgent issue requiring confirmation or refutation in the context of the current search for high temperature conventional superconductivity.

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“…5 tells us how much the potential well has to be deepened in aluminium and lead in the normal state. See [21] to appreciate how much it has to be deepened in niobium and tantalum.…”

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

“…for electron relaxation time in metals that leads through the Drude formula to ρ(T ), x = ν/k B T [21] with k B being the Boltzmann constant. Eq.…”

Section: Electrical Resistivitymentioning

confidence: 99%

Section: Resistivity Inversionmentioning

confidence: 99%

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Comparison of Heine–Abarenkov and alternative pseudopotentials for electron–phonon interaction in aluminium, lead, lithium and calcium

Zheng

Walmsley

2017

Solid State Communications

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“…These lead to δV = −4.142 (in Fermi energy) and r 1 = 1.045 (in crystal constant) in Eq. (4) Tantalum phonons are discussed in [43], experimental resistivity is from the Bloch-Grünison formula [33] and tunnelling conductance is reported in [39]. These lead to δV = −4.542 (in Fermi energy) and r 1 = 1.058 (in crystal constant) in Eq.…”

Section: Aluminium Niobium and Tantalummentioning

confidence: 99%

BCS theory has to be overhauled: Reassurance from numerical survival rate

Zheng¹,

Walmsley²

2016

Solid State Communications

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The BCS theory has conceptual and numerical difficulties. We have previously overhauled it with a new scheme of phonon-mediated electron pairing that can be expressed analytically in terms of an empirical pairing survival rate factor, S(q) = 0 or 1/2, depending on phonon momentum, q. Now we evaluate S(q) numerically entirely from experimental data on normal state electrical resistivity and on superconducting tunnelling conductance. The empirical and numerical S(q) are reassuringly close in aluminium and lead and particularly so in two other cases, niobium and tantalum.

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Visualised predictions of gap anisotropy to test new electron pairing scheme

Zheng

Walmsley

2017

Physica C: Superconductivity and its Applications

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The rich and fertile but not yet adequately exploited ground of superconductor anisotropy is proposed as a test bed for a new empirical scheme of electron pairing. The scheme is directed to resolving a numerical and conceptual difficulty in the BCS theory. The original theoretical formulation of the anisotropy problem by Bennett is adopted and its outcomes extensively explored. Here the Bennett conclusion that in metallic superconductors phonon anisotropy is the principal source of gap anisotropy is accepted. Values of the energy gap are visualised globally in k-space with unprecedented detail and accuracy. Comparison is made between the anisotropy pattern from the new and the usual BCS pairing schemes. Differences are revealed for future experimental resolution.

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Evidence for Effective Weakening of Electron-Phonon Interaction in Superconducting Tantalum, Niobium, Lead and Aluminum

Cited by 6 publications

References 29 publications

Comparison of Heine–Abarenkov and alternative pseudopotentials for electron–phonon interaction in aluminium, lead, lithium and calcium

Comparison of Heine–Abarenkov and alternative pseudopotentials for electron–phonon interaction in aluminium, lead, lithium and calcium

BCS theory has to be overhauled: Reassurance from numerical survival rate

Visualised predictions of gap anisotropy to test new electron pairing scheme

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