Effects of Spin Fluctuations in Quasi-One-Dimensional Organic Superconductors

TL;DR

This paper investigates the electronic states of quasi-one-dimensional organic conductors using the Hubbard model and FLEX method, revealing pseudogap formation, d-wave superconductivity, and pressure-dependent magnetic transition behaviors.

Contribution

It applies the FLEX method to study the phase diagram and physical properties of organic conductors, providing insights into pseudogap and superconductivity phenomena.

Findings

Pressure dependence of Neel temperature matches experiments

Pseudogap forms near the chemical potential

d-wave superconductivity appears adjacent to antiferromagnetic state

Abstract

We study the electronic states of quasi-one-dimensional organic conductors using the single band Hubbard model at half-filling. We treat the effects of the on-site Coulomb interaction by the fluctuation-exchange (FLEX) method, and calculate the phase diagram and physical properties. The calculated pressure dependence of the Neel temperature coincides well with the experimental one. We also show that a pseudogap is formed in the density of states near the chemical potential and that d-wave superconductivity appears next to the antiferromagnetic state. Moreover the NMR relaxation rate increases on cooling in the low-temperature region.