Unified Description of Charge Density Waves in Electron- and Hole-doped Cuprate Superconductors

TL;DR

This study investigates the relationship between charge density waves and superconductivity in electron-doped cuprates, revealing a weakened CDW order within the superconducting phase and proposing a unified phenomenological framework for cuprates.

Contribution

It provides the first detailed analysis of CDW in electron-doped cuprates and introduces the CDW correlation length as a key parameter for understanding their interplay with superconductivity.

Findings

Short-range CDW order exists across a wide doping range.

CDW order weakens inside the superconducting phase near optimal doping.

A unified phenomenological picture for CDW and SC in cuprates is proposed.

Abstract

High-temperature cuprates superconductors are characterised by the complex interplay between superconductivity (SC) and charge density wave (CDW) in the context of intertwined competing orders. In contrast to abundant studies for hole-doped cuprates, the exact nature of CDW and its relationship to SC was much less explored in electron-doped counterparts. Here, we performed resonant inelastic x-ray scattering (RIXS) experiments to investigate the relationship between CDW and SC in electron-doped La$_{2-x}$Ce$_x$CuO$_4$. The short-range CDW order with a correlation length $\sim35$~\AA~was found in a wide range of temperature and doping concentration. Near the optimal doping, the CDW order is weakened inside the SC phase, implying an intimate relationship between the two orders. This interplay has been commonly reported in hole-doped La-based cuprates near the optimal doping. We reconciled the diverging behaviour of CDW across the superconducting phase in various cuprate materials by introducing the CDW correlation length as a key parameter. Our study paves the way for establishing a unified picture to describe the phenomenology of CDW and its relationship with SC in the cuprate family.