Superconducting systems of low dimensionality
Author(s)
Advisor
Çıracı, SalimDate
1992Publisher
Bilkent University
Language
English
Type
ThesisItem Usage Stats
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Abstract
It is possible to call the last five years as the golden age of superconductivity.
The two most important developments in the field are the discovery of copper
oxide and fullerene superconductors. In this work, some possible pairing
mechanisms for these materials ai’e examined by giving emphasis on the reduced
dimensionality. First, an older problem, spatially separated electron-hole system,
is investigated to identify the possible phases in coupled double quantum well
structures in electric field. Secondly, the superconducting transition temperature
and response to external magnetic fields of layered systems with varying number
of layers are studied by means of a microscopic model and its GinzburgLandau
version. It is also shown that an interlayer pairing mechanism, phonon
assisted tunneling, can induce superconductivity. Finally, effects of the spherical
structure of fullerenes are examined by solving a two fermion problem on
an isolated molecule where the particles interact via a short range attractive
potential. As a possible mechanism of superconductivity in alkali metal doped
fullerenes, coupling between electrons and the radial vibrations of the molecule
is investigated.
Keywords
SuperconductivityCoupled double quantum wells
Spatially separated electron-hole system
Kosterlitz-Thouless transition
Wigner crystal
Exciton condensation
Layered superconductors
Superconductor-insulator superlattices
Superconducting thin films
High temperature superconductors
Phonon assisted tunneling
Electron-phonon interaction
Fullerenes
Bound-state formation
Polaron
Negative U Hubbard model