Superconductivity and Density Wave in the Quasi-One-Dimensional Systems: Renormalization Group Study

TL;DR

This study uses renormalization group techniques to analyze superconductivity and density waves in quasi-one-dimensional systems, revealing how interactions influence phase transitions and pairing symmetries, with implications for experimental materials.

Contribution

It provides a detailed phase diagram and shows how next-nearest neighbor interactions affect pairing states and transition temperatures in quasi-one-dimensional systems.

Findings

Temperature dependence of response functions is exponential in a wide temperature range.

Next-nearest neighbor interactions suppress d-wave singlet and promote f-wave triplet superconductivity.

Field-induced f-wave triplet pairing may occur in certain materials.

Abstract

The anisotropic superconductivity and the density wave have been investigated by applying the Kadanoff-Wilson renormalization group technique to the quasi-one-dimensional system with finite-range interactions. It is found that a temperature (T) dependence of response functions is proportional to exp(1/T) in a wide region of temperature even within the one-loop approximation. Transition temperatures are calculated to obtain the phase diagram of the quasi-one-dimensional system, which is compared with that of the pure-one-dimensional system. Next-nearest neighbor interactions (V_2) induce large charge fluctuations, which suppress the d_{x^2 -y^2}-wave singlet superconducting (dSS) state and enhance the f-wave triplet superconducting (fTS) state. From this effect, the transition temperature of fTS becomes comparable to that of dSS for large V_2, so that field-induced f-wave triplet pairing could be possible. These features are discussed to comprehend the experiments on the (TMTSF)_2PF_6 salt.