Determining the effect of defects pinning on the nematic response to uniaxial pressure of 2D charge density waves in YBa2Cu3O6+x

Our pioneering x-ray scattering work using uniaxial pressure has shown that 2D charge density waves (CDW) are enhanced in the direction perpendicular to that of applied compressive strain in YBa2Cu3O6+x (YBCO) crystals. Our results can be explained in terms of strong nematic response on top of pre-existing domains pinned by defects. During our previous beamtime, we carried out Cu-L3 resonant inelastic x-ray scattering on YBCO under uniaxial pressure and investigated the defect-pinned 2D-CDW scenario. We cooled the crystals after having applied uniaxial strain at high temperature and we compared intensities and correlation of the a- and b-CDW peaks at Tc: the CDW perpendicular to strain was enhanced whereas the parallel CDW is reduced, differently from previous experiments without strain cooling. We propose to continue this investigation in order to draw a clear picture of the effect of uniaxial strain on YBCO and the pinned nature of the 2D CDW state.