Universal Stripe Symmetry of Short-Range Charge Density Waves in Cuprate Superconductors

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 is challenging for the short-range CDW in bismuth-based cuprates. Here, high-resolution resonant inelastic x-ray scattering is employed to uncover the spatial symmetry of the CDW in Bi2Sr2 - xLaxCuO6 + delta. Across a wide range of doping and temperature, anisotropic CDW peaks with elliptical shapes are found in reciprocal space. Based on Fourier transform analysis of real-space models, the results are interpreted as evidence of unidirectional charge stripes, hosted by mutually 90 degrees-rotated anisotropic domains. This work paves the way for a unified symmetry and microscopic description of CDW order in cuprates. The symmetry of charge-density-wave (CDW) in copper-oxide superconductors is an important clue for the longstanding conundrum of high-temperature superconductivity. This novel RIXS mapping study corroborates unidirectional stripe as a fundamental symmetry of CDWs across cuprate materials. This remarkable universality provides a new perspective on the unified organizing principle of CDW and its role in the phase diagram of copper-oxide superconductors.image