The amplitudes and the structure of the charge density wave in YBCO

TL;DR

This paper identifies unknown s- and d-wave amplitudes of the charge density wave in underdoped cuprates through combined experimental data analysis, revealing amplitude variations with magnetic field and temperature, and constraining possible CDW mechanisms.

Contribution

It provides the first detailed analysis of the amplitudes and structure of the CDW in YBCO, including ruling out checkerboard patterns and certain mechanisms.

Findings

Doping modulation amplitude is 3.5×10^{-3} at 60K and low magnetic field.

Amplitude increases to 6.5×10^{-3} at 1.3K and 30T.

Data exclude checkerboard pattern and mechanisms without phonons.

Abstract

We find unknown $s$- and $d$-wave amplitudes of the recently discovered charge density wave (CDW) in underdoped cuprates. To do so we perform a combined analysis of experimental data for ortho-II YBa$_2$Cu$_3$O$_{y}$. The analysis includes data on nuclear magnetic resonance, resonant inelastic X-ray scattering, and hard X-ray diffraction. The amplitude of doping modulation found in our analysis is $3.5\cdot 10^{-3}$ in a low magnetic field and $T=60$K, the amplitude is $6.5\cdot 10^{-3}$ in a magnetic field of 30T and $T=1.3$K. The values are in units of elementary charge per unit cell of a CuO$_2$ plane. We show that the data rule out a checkerboard pattern, and we also show that the data might rule out mechanisms of the CDW which do not include phonons.