dc.contributor.advisor |
Vidhyadhiraja, N.S. |
en_US |
dc.contributor.author |
Kamar, Naushad Ahmad |
|
dc.date.accessioned |
2014-09-22T03:52:22Z |
|
dc.date.available |
2014-09-22T03:52:22Z |
|
dc.date.issued |
2014-09-22 |
|
dc.date.issued |
2013 |
en_US |
dc.identifier.citation |
Kamar, Naushad Ahmad. 2013, Disorder and proximity driven phenomena in s-wave superconductors, MS thesis, Jawaharlal Nehru Centre for Advanced Scientific Research, Bengaluru |
en_US |
dc.identifier.uri |
https://libjncir.jncasr.ac.in/xmlui/handle/10572/1404 |
|
dc.description.abstract |
In this thesis, we have investigated two important issues in s-wave superconductors, namely effects of disorder and the proximity to normal metal on the superconducting state. The present thesis
employs the framework of dynamical mean field theory (DMFT). We have developed extensions to
the well-benchmarked impurity solver - iterated perturbation theory for superconductivity (IPTSC),
and have used it within DMFT to study the above mentioned phenomena. The thesis has been divided
into three chapters. Chapters two and three deal with effects of disorder on s-wave superconductors
and chapter four deals with proximity of s-wave superconductor to normal metal. The three chapters
are summarized below.
In Chapter 2, the disordered attractive Hubbard model is studied by combining dynamical mean
field theory (DMFT), coherent potential approximation (CPA) and iterated perturbation for superconductivity (IPTSC) as an impurity solver. The disorder is modeled by taking random values of
site-energies. We find that the superconducting order parameter (Φ) decreases with increasing disorder strength (x) and beyond a critical value of x = xc, it completely vanishes, and system becomes
non-superconducting. The spectral gap (Eg) shows non-monotonic behaviour. For weak x, Eg decreases with increasing x, and after a certain value of x, it increases with increasing x. Even after
the destruction of superconductivity (Φ = 0), the spectral gap persists, thus the system goes being
a superconductor to an insulator with increasing disorder. We have calculated the phase diagram
in interaction-disorder plane. It is found that xc initially increases with increasing interaction (U),
reaches a maximum and then decreases with increasing U. Thus superconductivity becomes less
robust in presence of disorder |
|
dc.language.iso |
English |
en_US |
dc.publisher |
Jawaharlal Nehru Centre for Advanced Scientific Research |
en_US |
dc.rights |
© 2013 JNCASR |
en_US |
dc.subject |
Proximity |
en_US |
dc.subject |
Superconductors |
|
dc.subject |
Waves |
|
dc.title |
Disorder and proximity driven phenomena in s-wave superconductors |
en_US |
dc.type |
Thesis |
en_US |
dc.type.qualificationlevel |
Master |
en_US |
dc.type.qualificationname |
MS Engg |
en_US |
dc.publisher.department |
Theoretical Sciences Unit (TSU) |
en_US |