Blackburn, E.2; Chang, J.3; Hücker, M.8; Holmes, A. T.2; Christensen, N. B.1; Liang, Ruixing5; Bonn, D. A.5; Hardy, W. N.5; Rütt, U.6; Gutowski, O.6; Zimmermann, M. V.6; Forgan, E. M.2; Hayden, S. M.7
1 Department of Physics, Technical University of Denmark2 University of Birmingham3 École Polytechnique Fédérale de Lausanne4 Brookhaven National Laboratory5 University of British Columbia6 Deutsches Elektronen-Synchrotron7 University of Bristol8 Brookhaven National Laboratory
X-ray diffraction measurements show that the high-temperature superconductor YBa2Cu3O6.54, with ortho-II oxygen order, has charge-density-wave order in the absence of an applied magnetic field. The dominant wave vector of the charge density wave is qCDW=(0,0.328(2),0.5), with the in-plane component parallel to the b axis (chain direction). It has a similar incommensurability to that observed in ortho-VIII and ortho-III samples, which have different dopings and oxygen orderings. Our results for ortho-II contrast with recent high-field NMR measurements, which suggest a commensurate wave vector along the a axis. We discuss the relationship between spin and charge correlations in YBa2Cu3Oy and recent high-field quantum oscillation, NMR, and ultrasound experiments.