X-ray search for CDW in single crystal YBa{sub 2}CU{sub 3}O{sub 7-{delta}}

Recently, H.L. Edwards et al. observed, in STM experiments at 20K, modulations in the CuO chain layer of cold-cleaved single crystals of YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} which they interpreted as a possible charge density wave (CDW). Since X-ray scattering is an ideal tool for the study of static or dynamic lattice displacements, we performed a synchrotron X-ray study at beamline X14 at the NSLS of BNL on a high quality single crystal of YBa{sub 2}Cu{sub 3}O{sub 7- {delta}}, which was mainly single domain with a spacially well localized volume fraction of other twin orientations of roughly 10%. Appropriate scattering configurations were chosen to enable observations of longitudinal or transverse CDWs with polarization either in the chain direction, {parallel} <001> or {perpendicular} to it in <001>. The X-ray energy of 16keV allowed us to reach large momentum transfers to increase the sensitivity to lattice displacements. In none of our scans, which definitely covered the case of a 1-dimensional longitudinal CDW with propagation in the b direction as proposed by Edwards et al., did we find intensity other than the main Bragg peak(s) and the twin reflections. We therefore suspect that the STM finding may be a surface-induced phenomenon