Persistent Charge Density Wave Memory in a Cuprate Superconductor

TL;DR

This study reveals that charge density wave domains in a cuprate superconductor exhibit persistent memory linked to structural domain patterns, even above the CDW onset temperature, highlighting complex charge-lattice interactions.

Contribution

It demonstrates direct measurement of CDW domain memory and its dependence on structural domain patterns using coherent resonant x-ray speckle correlation analysis.

Findings

CDW domain patterns are highly reproducible upon thermal cycling below 54 K.

Memory of CDW domains is lost when crossing the structural transition at 240 K.

Structural domain twinning influences CDW pinning landscape.

Abstract

Although charge density wave (CDW) correlations appear to be a ubiquitous feature of the superconducting cuprates, their disparate properties suggest a crucial role for coupling or pinning of the CDW to lattice deformations and disorder. While diffraction intensities can demonstrate the occurrence of CDW domain formation, the lack of scattering phase information has limited our understanding of this process. Here, we report coherent resonant x-ray speckle correlation analysis, which directly determines the reproducibility of CDW domain patterns in La1.875Ba0.125CuO4 (LBCO 1/8) with thermal cycling. While CDW order is only observed below 54 K, where a structural phase transition results in equivalent Cu-O bonds, we discover remarkably reproducible CDW domain memory upon repeated cycling to temperatures well above that transition. That memory is only lost on cycling across the transition at 240(3) K that restores the four-fold symmetry of the copper-oxide planes. We infer that the structural-domain twinning pattern that develops below 240 K determines the CDW pinning landscape below 54 K. These results open a new view into the complex coupling between charge and lattice degrees of freedom in superconducting cuprates.