Temperature-dependent modulation amplitude of the ${\mathrm{CuO}}_2$ superconducting lattice in ${\mathrm{La}}_2$${\mathrm{CuO}}_{4.1}$

The temperature-dependent amplitude of the Cu-O(planar) bond modulation in the ${\mathrm{La}}_2$${\mathrm{CuO}}_{4.1}$ superconducting crystal has been measured by in-plane-polarized Cu K-edge extended x-ray-absorption fine structure. Minority domains characterized by a long Cu-O(planar) bond length are found at T<150 K. The separation between the two Cu-O(planar) distances provides a measure of the amplitude of the ${\mathrm{CuO}}_2$ lattice modulation assigned to a charge-density wave that coexists with the superconducting phase, providing evidence for a broken symmetry.