Features of the Holographic Superconductors

Pal, Suchetana (2022) Features of the Holographic Superconductors. PhD thesis, Indian Institute of Science Education and Research Kolkata.

Text (PhD thessi of Suchetana Pal (15RS004)) 15RS004.pdf - Submitted Version Restricted to Repository staff only Download (1MB)

Abstract

In this thesis, we investigate different features of holographic superconductors. The properties of an s-wave holographic superconductor near critical temperature are analyzed using the matching method. The critical temperature - charge density relationship is established, including the effects of backreaction on spacetime. These findings indicate that the condensation gets harder to form as we include backreaction. Then, we analyze a p-wave holographic superconductor model in the framework of Einstein-Yang-Mills theory. The frequency-dependent expression of conductivity and the band gap energy is derived for this model analytically. We also use the self-consistent approach to obtain the expressions of conductivity for different frequency ranges. We then compare the imaginary part of conductivity in the low-frequency region. The band gap energy obtained from these two methods seems to agree very well. These results are then numerically verified. Next, we proceed to investigate the effect of an external magnetic field on the s-wave holographic superconductor in the presence of backreaction. The expression of the upper critical magnetic field Bc is obtained above which the superconducting phase vanishes. The results show a decrease in the critical magnetic field Bc with an increasing backreaction parameter. Lastly, we analyze a holographic superconductor in the framework of power Maxwell electrodynamics taking into account the effects of spacetime noncommutativity. The critical temperature - charge density relationship and the value of the condensation operator are obtained. The Meissner-like effect is also studied. The results indicates that larger values of the noncommutative parameter and the parameter q appearing in the power Maxwell theory makes the condensate difficult to form. The ratio Bc/T²c at T = 0, however increases with increase in the noncommutative parameter θ.

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