The Theory of Superconductivity and Some Electron Pairing Mechanis
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Date
1988-06
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Addis Ababa University
Abstract
The recent discovery of high··temperature superconductivity brought
about the necessity of clal'ifying a set of questions. One of these is regarding
the electron pairing mechanism. Upto now, we have a well-developed
microscopic theory of the conventional supel'conductivity, the so-called BCS
theory. lIs we know, the pairing of electrons in this theory is realiz!!d
through the exchange of virtual phonons. This mechanism leads to the existence
of energy gap in the spectrum of elementary excitations of low-temperature
superconductivity. And, in the absence of magnetic field, it is known
that the normal-superconducting transition is second-order phase transition.
ThllS, the BCS theory gives the recipe for calculating all physical quantities
of cOllventional superconductors.
The situation with the high-temperature superconductivity ;s much more
complex. The mechaIYism of high - Tc superconductivity is still unkonwn. This
is the reason we decided to give in this pape!' the revie~1 of conventional
phenomenological t,heories of superconductivity and give new formulation of
BCS theory ;,/hich is b,lsed on retarded thermal Green's function method. We
a 1 so attempted to analyze the ava i1 ab 1 e eXperimenta 1 data on hi gh - T c and
some of the pairing mechanisms discussed in the literature. We finally
Pt'oposed a mode 1 ~/hich can execute hi gil-temperature superconduct; vity where
.' '?
electrons are paired by the exchange of virtual plasmons which can be OOset'ved
in some specially prepal'ed thin films
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Keywords
The Theory of superconductivity