Coincident onset of charge density wave order at a quantum critical point in underdoped YBCO

TL;DR

This study uses advanced x-ray scattering with high magnetic fields to investigate charge density wave order in underdoped YBCO, revealing that CDW order emerges near a quantum critical point within the superconducting phase.

Contribution

It demonstrates the onset of charge density wave order in underdoped YBCO near a quantum critical point using high-field x-ray scattering techniques.

Findings

No CDW detected below doping level p1~0.08

CDW onset occurs inside the superconducting dome

Broken translational symmetry linked to the QCP at p1

Abstract

The recently demonstrated x-ray scattering approach using a free electron laser with a high field pulsed magnet has opened new opportunities to explore the charge density wave (CDW) order in cuprate high temperature superconductors. Using this approach, we substantially degrade the superconductivity with magnetic fields up to 33 T to investigate the onset of CDW order in YBa$_2$Cu$_3$O$_x$ at low temperatures near a putative quantum critical point (QCP) at $p_1\sim $ 0.08 holes per Cu. We find no CDW can be detected in a sample with a doping concentration less than $p_1$. Our results indicate that the onset of the CDW ground state lies inside the zero-field superconducting dome, and broken translational symmetry is associated with the putative QCP at $p_1$