d_{x^2-y^2}-Wave Pairing Fluctuations and Pseudo Spin Gap in Two-Dimensional Electron Systems

TL;DR

This paper investigates the pseudogap phenomena in high-T_c cuprates by analyzing AFM and d-wave superconducting fluctuations, revealing a mechanism where d-wave short-range order dominates and influences pseudogap formation.

Contribution

It introduces a theoretical framework using auxiliary fields and SCR to explain pseudogap formation as a result of d-wave SRO over AFM-SRO in 2D electron systems.

Findings

Pseudogap arises from dominant d-wave short-range order.

Damping dependence on dSC correlation length explains underdoped pseudogap.

Pseudogap region varies with doping, shrinking in overdoped cuprates.

Abstract

Pseudogap phenomena of high-T_c cuprates are examined. In terms of AFM (antiferromagnetic) and dSC (d_{x^2-y^2}-wave superconducting) auxiliary fields introduced to integrate out the fermions, the effective action for 2D electron systems with AFM and dSC fluctuations is considered. By the self-consistent renormalization (SCR), the NMR relaxation rate T_1^{-1}, the spin correlation length \xi_\sigma and the pairing correlation length \xi_d are calculated. From this calculation, a mechanism of the pseudogap formation emerges as the region of dominant d-wave short-range order (SRO) over AFM-SRO. When damping for the AFM fluctuation strongly depends on the dSC correlation length through the formation of precursor singlets around (\pi,0) and (0,\pi) points in the momentum space, the pseudogap appears in a region of the normal state characterized by decreasing 1/T_1T and increasing AFM correlation length with decrease in temperature. This reproduces a characteristic feature of the pseudogap phenomena in many underdoped cuprates. When the damping becomes insensitive to the dSC correlation length, the pseudogap region shrinks as in the overdoped cuprates.