# Formation of Incommensurate Charge Density Waves in Cuprates

## TL;DR

This study reveals that charge density waves in cuprates develop in two stages, with a doping-independent precursor phase that seeds the low-temperature, doping-dependent CDW, shedding light on their complex formation mechanism.

## Contribution

It uncovers a two-stage development of CDWs in cuprates, highlighting a precursor phase and its phase mode as fundamental to understanding their electronic ground state.

## Key findings

- Precursor CDW appears at high temperature with a quasi-commensurate wavevector.
- The precursor CDW is doping-independent and originates from a phase mode coupled with a phonon.
- The low-temperature CDW is strongly doping-dependent and seeded by the precursor phase.

## Abstract

Although charge density waves (CDWs) are omnipresent in cuprate high-temperature superconductors, they occur at significantly different wavevectors, confounding efforts to understand their formation mechanism. Here, we use resonant inelastic x-ray scattering to investigate the doping- and temperature-dependent CDW evolution in La2-xBaxCuO4 (x=0.115-0.155). We discovered that the CDW develops in two stages with decreasing temperature. A precursor CDW with quasi-commensurate wavevector emerges first at high-temperature. This doping-independent precursor CDW correlation originates from the CDW phase mode coupled with a phonon and "seeds" the low-temperature CDW with strongly doping dependent wavevector. Our observation reveals the precursor CDW and its phase mode as the building blocks of the highly intertwined electronic ground state in the cuprates.