Polar Charge Fluctuation and Superconductivity in Organic Conductor

TL;DR

This paper investigates how polar charge fluctuations influence superconductivity in an organic conductor, revealing the role of intra-dimer polarization and lattice geometry in pairing mechanisms.

Contribution

It introduces an extended Hubbard model analysis incorporating intra-dimer structure and Coulomb interactions to explore superconductivity near polar charge-density wave phases.

Findings

Superconductivity emerges near polar charge-density wave phases.

Extended s-wave pairing is favored in the studied system.

Lattice geometry affects the competition between different pairing mechanisms.

Abstract

Superconductivity and polar charge fluctuation are studied in an organic conductor with the dimer-molecule degree of freedom. The extended Hubbard models, where the intra-dimer electronic structure and the inter-dimer Coulomb interactions are taken into account, are analyzed by the random-phase approximation and the fluctuation-exchange approximation. Superconductivity appears in a vicinity of the charge-density wave (CDW) phase where the electronic charge distributions are polarized inside of dimers. The extended s-wave type paring is favored and its competitive relations with the superconductivity due to the spin fluctuation depends on the triangular lattice geometry. Comparison between two superconductivities realized near the polar and non-polar CDW phases are also presented.