Excitation spectrum of d-wave Fermi surface deformation

TL;DR

This paper investigates the excitation spectrum of d-wave Fermi surface deformation in high-Tc cuprates, revealing a low-energy peak in the normal state and a high-energy overdamped mode in the pairing state, highlighting the competition between these instabilities.

Contribution

It provides a detailed analysis of the dFSD excitation spectrum using the random phase approximation, showing how critical fluctuations are suppressed by d-wave pairing.

Findings

Low energy peak in normal state excitation spectrum

High energy overdamped collective mode in pairing state

Competition suppresses critical fluctuations of dFSD

Abstract

Several instabilities competing with the d-wave singlet pairing were proposed for high-Tc cuprates. One of them is the d-wave Fermi surface deformation (dFSD), which is generated by forward scattering. In this paper, correlation functions of the dFSD are calculated within the random phase approximation. In the normal state, the excitation spectrum shows a low energy peak, which smoothly connects to critical fluctuations of the dFSD at lower temperature. The competition with the d-wave pairing, however, blocks the critical fluctuations. The whole spectral weight is transferred to high energy and a pronounced peak appears there in the d-wave pairing state. This peak is an overdamped collective mode of the dFSD and can grow to be a resonance mode at moderate finite wavevectors.