Electron pairing and evidence of a BCS–BEC crossover in d-wave superconductors

Abstract

We have demonstrated that it is possible to access a crossover scenario starting with a weak coupling (BCS) d-wave superconductor to a strongly coupled Bose-Einstein condensate (BEC) phase as the exchange interaction is tuned in a two dimensional system described by a t-J-U model via numerically solving the Bogoliubov-de Gennes (BdG) equations. While in the extreme dilute limit, the electronic pairing phenomena is independent of the Coulomb repulsion, U , the superconductivity depends on U , and so does the crossover. Further, the effect of variation in the carrier density on the BCS-BEC crossover has also been investigated. The crossover picture is illustrated by computing the chemical potential, which when falls below the noninteracting band minimum, signals the onset of a phase with tightly bound, shorter pairs. As an evidence of the above feature, the Cooper pair radius is calculated which shows a significant shortening at the emergence of a BEC-like phase. Besides, in contrast to the previous work where a crossover was claimed only in the dilute limit, we have demonstrated it at large densities near half filling.

Reusable, Free‐Standing MoS2/rGO/Cu2O Ternary Composite Films for Fast and Highly Efficient Sunlight Driven Photocatalytic Degradation

“…[34] This binary component structure without any conductive network suffers from longer duration of degradation and low rate of kinetics compared to other reported ternary composites. In addition to the abovementioned materials, the various reported photocatalysts like TiO 2 nanobelts coated with MoS 2 nanosheets, [31] MoS 2 nanoflower/TiO 2 (B) nanobelts, [35] Cu 2 O/rGO, [19] etc. also had limitation of longer degradation time.…”

“…[18] A recent study by Kumar et al on Cu 2 O grown on rGO for its photocatalytic degradation reveals the advantages of visible light utilization and good photocatalytic activity. [19] However, these above-mentioned photocatalysts are utilized in powder form to degrade the organic dye solutions which require particular quantity of the active material for complete degradation. Also, the recovery of photocatalyst from the dye solution after photocatalysis is difficult which involves centrifugation and filtration.…”