Stripe Symmetry of Short-range Charge Density Waves in Cuprate Superconductors

TL;DR

This study uses advanced x-ray scattering to determine that short-range charge density waves in bismuth-based cuprate superconductors have a stripe symmetry, revealing unidirectional charge stripes across various doping levels and temperatures.

Contribution

It provides direct experimental evidence that short-range CDWs in Bi-based cuprates exhibit stripe symmetry, resolving a longstanding debate in the field.

Findings

Anisotropic elliptical CDW peaks indicate unidirectional charge stripes.

Charge stripes are hosted by mutually 90°-rotated anisotropic domains.

Results suggest a unified microscopic understanding of CDW order in cuprates.

Abstract

The omnipresence of charge density waves (CDWs) across almost all cuprate families underpins a common organizing principle. However, a longstanding debate of whether its spatial symmetry is stripe or checkerboard remains unresolved. While CDWs in lanthanum- and yttrium-based cuprates possess a stripe symmetry, distinguishing these two scenarios has been challenging for the short-range CDW in bismuth-based cuprates. Here, we employed high-resolution resonant inelastic x-ray scattering to uncover the spatial symmetry of the CDW in Bi$_2$Sr$_{2-x}$La$_{x}$CuO$_{6+\delta}$. Across a wide range of doping and temperature, anisotropic CDW peaks with elliptical shapes were found in reciprocal space. Based on Fourier transform analysis of real-space models, we interpret the results as evidence of unidirectional charge stripes, hosted by mutually 90$^\circ$-rotated anisotropic domains. Our work paves the way for a unified symmetry and microscopic description of CDW order in cuprates.