Tuning charge density wave order and structure via uniaxial stress in a stripe-ordered cuprate superconductor

Unidirectional spin and charge density wave order in the cuprates is known to compete with superconductivity. In the stripe order (La,M)$_2$CuO$_4$ family of cuprates, spin and charge order occur as unidirectional order that can be stabilized by symmetry breaking structural distortions, such as the low temperature tetragonal (LTT) phase. Here we examine the interplay between structure and the formation of charge density wave (CDW) order in the LTT phase of La$_{1.475}$Nd$_{0.4}$Sr$_{0.125}$CuO$_4$ by applying uniaxial stress to distort the structure and influence the formation of CDW order. Using resonant soft x-ray scattering to measure both the CDW order and (0 0 1) structural-nematic Bragg peaks, we find that the application of uniaxial stress along the Cu-O bond direction suppresses the (0 0 1) peak and has the net effect of reducing CDW order, but does so only for CDW order propagating parallel to the applied stress. We connect these observations to previous work showing an enhanced superconducting transition temperature under uniaxial stress; providing insight into how CDW, superconductivity, nematicity, and structure are related and can be tuned relative to one another in cuprates.