TITLE:
The Influence of Electron Transfer on Tc in Superconductors
AUTHORS:
Joachim Sonntag
KEYWORDS:
High-Tc Superconductor, Electron Transfer, Electron Density, Hole Density, Cooper Pairs, Cermets, Granular Metals, Metal-Metal Sandwiches
JOURNAL NAME:
World Journal of Condensed Matter Physics,
Vol.14 No.4,
November
28,
2024
ABSTRACT: Increase of Tc in Al1−x(SiO2)x cermets with increasing x is caused by electron transfer from the Al grains to the SiO2 phase occupying surface states, expressed by
T
c
/
T
c,max
=1−γ⋅
n
2
(*), where n is the electron density in the Al phase and
γ
a characteristic parameter. Decrease of Tc in Pb-Cu-sandwiches is attributed to the electron transfer from the Cu film to the Pb film.
γ
and
T
c,max
in equation (*) stands for the influence of the electron-phonon interaction and
n
2
for the influence of the electron-electron Coulomb repulsion on Tc. The result that equation (*) holds for both hole-doped cuprate high-temperature superconductivity (HTSC) and Al1−x(SiO2)x cermets is an important indication that common mechanisms underlie HTSC and classical superconductors. The difference between the two is that in HTSC, electron transfer occurs between different electronic bands, but in Al1−x(SiO2)x cermets between different phases.