Supeconductivity in the Pseudogap State in "Hot - Spots" Model: Ginzburg - Landau Expansion

TL;DR

This paper develops a microscopic Ginzburg-Landau theory for superconductivity emerging within the pseudogap state, considering both s-wave and d-wave pairing, and analyzes how short-range order fluctuations affect critical temperature and thermodynamic properties.

Contribution

It provides a detailed derivation of the Ginzburg-Landau expansion accounting for short-range order fluctuations in a hot-spot model, revealing their impact on superconducting characteristics.

Findings

Critical temperature depends on pseudogap width and fluctuation correlation length.

Superconducting transition shows reduced specific heat discontinuity in the pseudogap region.

Superconducting properties are significantly influenced by electron scattering near hot spots.

Abstract

We analyze properties of superconducting state (for both s-wave and d-wave pairing), appearing on the "background" of the pseudogap state, induced by fluctuations of "dielectric" (AFM(SDW) or CDW) short -- range order in the model of the Fermi surface with "hot spots". We present microscopic derivation of Ginzburg - Landau expansion, taking into account all Feynman diagrams of perturbation theory over electron interaction with this short - range order fluctuations, leading to strong electronic scattering in the vicinity of "hot spots". We determine the dependence of superconducting critical temperature on the effective width of the pseudogap and on correlation length of short - range order fluctuations. We also find similar dependences of the main characteristics of such superconductor close to transition temperature. It is shown particularly, that specific heat discontinuity at the transition temperature is significantly decreased in the pseudogap region of the phase diagram.