The electron-phonon coupling and phonon spectra in lead-thallium alloys studied by electron tunnelling

Claeson, T.; Grimvall, Göran

doi:10.1016/0022-3697(68)90084-x

Cited by 18 publications

(2 citation statements)

References 33 publications

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“…We have just mentioned that in a single crystal one has to take into account the directional dependence of the interaction. Even in a certain direction there can be more than one gap due to electrons appears, as expected, if disorder is introduced, for example as the film is made thin or at alloying (it remains, though, to surprisingly high impurity contents [106,1071). A dirty superconductor is more ideal, more isotropic, than a pure one.…”

Section: 23mentioning

confidence: 59%

The Microscopic Theory of Superconductivity–Verifications and Extensions

Claeson¹,

Lundqvist²

1974

Phys. Scr.

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The microscopic theory of superconductivity was formulated in 1957 by Bardeen, Cooper, and Schrieffer. In the BCS model, the ground state of super electrons is built up by pairs kept together by an attractive interaction. An exchange of phonons can give such an attraction. The electrons in the superconducting condensate are correlated within a macroscopic distance. To excite electrons, or break pairs, a certain gap energy is needed. A number of experimental confirmations were discussed already in the original paper. The BCS theory initiated many experiments. Some of them provided a stimulus to logical extensions of the theory. These have mainly been concerned with a more realistic, energy-and momentum-dependent interaction than the original approximation. Lifetime aspects are also of importance. In this short survey we describe the results of a few experiments that test the concepts of pairing, energy gap and phonon-mediated attraction. The main emphases are on the powerful tunneling method and the variation of the superconducting transition temperature with different physical and chemical parameters.

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Section: 23mentioning

confidence: 59%

The Microscopic Theory of Superconductivity–Verifications and Extensions

Claeson¹,

Lundqvist²

1974

Phys. Scr.

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“…The tunneling spectroscopy in superconductors is a sensitive tool traditionally used to measure the energy gap and the energy spectrum of bosons coupled to electrons, be it internal [1][2][3][4] or external [5]. Its modification to tunneling, through ultrasmall metallic grains, made it possible to observe size and even-odd effects predicted by non-BCS treatments [6][7][8][9] of the Richardson model.…”

Section: Introductionmentioning

confidence: 99%

Tunneling spectroscopy of superconducting nanospheres

Hopjan

Lipavský

2014

Phys. Rev. B

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Superconductivity for ternary F.C.C. BiPbTl Alloys

Claeson

Munkby

Wingbro

1970

Physica Status Solidi (b)

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The superconducting transition temperature has been measured for several f.c.c. ternary Bi-Pb-T1 alloys. The transition temperature is essentially determined by the number of valence electrons per atom. A phase transition to a h.c.p. phase extends from BiTI, into the ternary system giving rise to broad transitions t o the superconducting state. The T, of a hypothetical f.c.c. T1 phase was extrapolated to 1.75 OK. The electron-phonon coupling strength could be estimated from T, and the Debye temperature using a theory by McMillan.The variation of the coupling strength with concentration of TI in P b shows a greater similarity with expectations regarding the density of electron states a t the Fermi level than with an empirical curve by McMillan based upon the phonon distribution.Die Supraleitungs-ifbergangstemperatur wurde fur verschiedene ternare k. f. z. Legierungen aus Wismut, Blei und Thallium gemessen. Die Ubergangstemperatur ist im wesentlichen von der Anzahl der Valenzelektronen pro Atom abhangig. Eine Phasenumwandlung in eine Phase hexagonal-dichtester Packung erstreckt sich von BiTl, in das ternare System und gibt Veranlassung zu breiten Ubergangen zum supraleitenden Zustand. Fur eine hypothetische k.f.z. Thallium-Phase wurde T, zu 1,75 OK extrapoliert. Es ist moglich, die Starke der Elektron-Phonon-Wechselwirkung aus Werten von TC und der Debye-Temperatur abzuschatzen. Die auf diese Weise berechnete StLrke der Wechselwirkung ist vom Thalliumanteil des Blei abhangig. Die Abhangigkeit befindet sich in besserer Ubereinstimmung mit Erwartungen, die von der Elektronendichte beim Bermi-Niveau ausgehen, als mit einer empirischen Kurve nach McMillan, die auf dem Phononenspektrum beruht. IntroductionA great number of investigations regarding the superconducting transition temperature, T,, in binary alloys have been performed [l, 21. Fewer determinations utilizing ternary alloys exist. Measurements on the Pb-T1 [3] and Bi-T1 [3,4] systems indicated that features in T, could be traced to the electronic structure of these alloys. As T1 (with 3 valence electrons per atom) and Bi (e/a = 5 ) are neighbours to P b (e/a = 4) in the periodic table, we felt that the ternary Bi-Pb-T1 system would be well suited for an investigation. The masses of the constituents are almost the same giving small effects of mass disorder. As a factor m / M (where m is the electron mass and M the ion mass)

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The electron-phonon coupling and phonon spectra in lead-thallium alloys studied by electron tunnelling

Cited by 18 publications

References 33 publications

The Microscopic Theory of Superconductivity–Verifications and Extensions

The Microscopic Theory of Superconductivity–Verifications and Extensions

Tunneling spectroscopy of superconducting nanospheres

Superconductivity for ternary F.C.C. BiPbTl Alloys

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