Effect of Fibonacci Modulation On Superconductivity

TL;DR

This study investigates how Fibonacci sequence-based disorder affects superconductivity in one-dimensional models, revealing suppression in strong coupling and enhancement in weak coupling, with differences depending on pairing mechanisms.

Contribution

It provides a comparative analysis of disorder effects on superconductivity in two different models, highlighting the role of pairing mechanisms and finite size effects.

Findings

Superconductivity is suppressed in strong coupling due to disorder.

Pairing correlations are enhanced in weak coupling regimes.

Differences arise between models due to their distinct pairing mechanisms.

Abstract

We have studied finite-sized single band models with short range pairing interactions between electrons in presence of diagonal Fibonacci modulation in one dimension. Two models, namely the attractive Hubbard model and the Penson-Kolb model, have been investigated at half-filling at zero temperature by solving the Bogoliubov-de Gennes equations in real space within a mean field approximation. The competition between ``disorder'' and the pairing interaction leads to a suppression of superconductivity (of usual pairs with zero centre-of-mass momenta) in the strong-coupling limit while an enhancement of the pairing correlation is observed in the weak-coupling regime for both the models. However, the dissimilarity of the pairing mechanisms in these two models brings about notable difference in the results. The extent to which the bond ordered wave and the $\eta$-paired (of pairs with centre-of-mass momenta = $\pi$) phases of the Penson-Kolb model are affected by the disorder has also been studied in the present calculation. Some finite size effects are also identified.