1212.3836 (E. Blackburn et al.)

Direct observation of charge density wave order at zero magnetic field
in ortho-II YBa$_2$Cu$_3$O$_{6.54}$    [PDF]

E. Blackburn, J. Chang, M. Hucker, A. T. Holmes, N. B. Christensen, Ruixing Liang, D. A. Bonn, W. N. Hardy, M. v. Zimmermann, E. M. Forgan, S. M. Hayden

X-ray diffraction measurements show that the high-temperature superconductor YBa$_2$Cu$_3$O$_{6.54}$, with ortho-II oxygen order, has charge density wave order (CDW) in the absence of an applied magnetic field. The CDW has a 1-q structure with the in-plane component of the wavevector parallel to the $\mathbf{b}$-axis (chain direction), with 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 wavevector along the $\mathbf{a}$-axis. We discuss the relationship between spin and charge correlations in YBa$_2$Cu$_3$O$_{y}$, and recent high-field quantum oscillation, NMR and ultrasound experiments.

View original: http://arxiv.org/abs/1212.3836