arXiv subjects

Soumi Roy Chowdhury

Publications and source records attributed to Soumi Roy Chowdhury.

4 recordsLinked to original sources

arXiv2018

Theoretical investigation of the feasibility of electronic mechanism for superconducting pairing in overdoped cuprates with Fermi liquid like and Marginal Fermi liquid- like descriptions for the normal phase

Cooper's formalism for fermionic pairing has been revisited considering upto 3rd neighbour hopping terms, firstly with a Fermi liquid like background on a square lattice keeping in mind the overdopped cuprates. Then the whole scheme is repeated with a Marginal Fermi liquid- like background, taking into account the self energy correction of the mobile electrons to include a more realitic density of states in the calculation. Detailed comparison of our theoretical results with those from experiments strongly supports the Marginal Fermi liquid- like character of the normal phase with exciton mediated superconducting pairing in the concerned materials, in the lightly overdoped phase.

cond-mat.supr-con↗

arXiv2016

Investigation of fermionic pairing on two- dimensional tight binding lattice under phonon and electronic mechanisms within a simple Fermi liquid like scenario and beyond- possible consequences for superconductivity in overdoped cuprates

Cooper's one pair problem is investigated for a 2D lattice in the background of both passive and active Fermi sea in a weakly correlated environment. Boson exchange mechanisms involving excitons as well as phonons are invoked for pairing in the s- wave channel. The important quantities calculated are pairing energy and coherence length as functions of bosonic energy, attracted coupling constant and band filling factor. Comparison of our theoretical results with those from experiments on overdoped cuprate superconductors and other type of theoretical calculations show electronic mechanism to be the more likely mechanism of pairing in the overdoped phase.

cond-mat.supr-con↗

arXiv2014

Investigation of fermionic pairing on tight binding lattice for low dimensional systems

Cooper's original one pair problem in continuum is revisited here corresponding to a lattice of tight binding nature, with an aim to investigate superconductivity in low dimensional systems. An electronic type of boson mediated attraction is considered for the pairing mechanism with the non trivial energy dependence of the electronic density of states taken into account in the calculation in a rigorous way. Some of the very important electronic and optical properties of a class of one dimensional organic conductors are used for the development of the formalism and calculation. The result of our calculations show that fermionic pair formation is indeed possible with some constraints. Similarities emerge in the physical properties of the electron pair formed from Cooper's treatment and ours excepting the striking difference appearing in the form of occurrence of a maximum allowed band filling for pairing and of an upper bound of the pairing energy found in our approach.

cond-mat.supr-con↗

arXiv2013

Can Excitonic Mechanism Contribute Significantly to Superconducting Pairing in Quasi 1-D Systems?

We have revisited Cooper's one pair problem of calculating the binding energy for two electrons, experiencing an attractive interaction near the Fermi surface, in case of quasi one dimensional lattice system. Though it is a generalized formalism, we have chosen two materials viz., (TMTSF)2ClO4 and (TMTSF)2AsF6 as examples. Some of their electronic and optical features are used for calculations and validity this formalism is checked too for these materials. It is generally believed that spin density fluctuation mechanism is very strong candidate for the occurrence of superconductivity in these quasi one dimensional materials. We have attempted to invoke another type of electronic mechanism viz., charge transfer Exciton mechanism to explore if some substantial contribution for attractive coupling can be generated. This mechanism may be plausible in these types of organic materials where ionicity and co-valency co-exist. Making use of the experimental results for optical absorption spectra corresponding to above materials, we extracted the relevant parameters for incorporating in the binding energy calculation. Our calculation shows that Fermionic pair formation is possible for all the three cases viz., (1) less than half filled, (2) half filled and (3) more than half filled.

cond-mat.supr-con↗