Quasiparticle interference and the interplay between superconductivity and density wave order in the cuprates

TL;DR

This paper presents a theoretical analysis of the Z-map in scanning tunneling spectroscopy, demonstrating how it reveals quasiparticle interference and distinguishes between different density wave orders in cuprate superconductors.

Contribution

It introduces a comprehensive theoretical framework for interpreting Z-map features, accounting for impurity scattering and particle-hole asymmetry in cuprates.

Findings

Z-map peaks vary with impurity types and bandstructure asymmetry

Fourier transform Z-map can detect density wave orders

Method distinguishes between different density wave states

Abstract

Scanning tunneling spectroscopy (STS) is a useful probe for studying the cuprates in the superconducting and pseudogap states. Here we present a theoretical study of the Z-map, defined as the ratio of the local density of states at positive and negative bias energies, which frequently is used to analyze STS data. We show how the evolution of the quasiparticle interference peaks in the Fourier transform Z-map can be understood by considering different types of impurity scatterers, as well as particle-hole asymmetry in the underlying bandstructure. We also explore the effects of density wave orders, and show that the Fourier transform Z-map may be used to both detect and distinguish between them.