S. Blanco-Canosa, A. Frano, T. Loew, Y. Lu, J. Porras, G. Ghiringhelli, M. Minola, C. Mazzoli, L. Braicovich, E. Schierle, E. Weschke, M. Le Tacon, B. Keimer
To gain insight into the influence of disorder on the electronic phase behavior of underdoped high-temperature superconductors, we have used resonant x-ray scattering to determine the momentum dependent charge correlations in YBa$_2$Cu$_3$O$_{6.5}$ samples with highly ordered chain arrays of oxygen acceptors (ortho-II structure). The results reveal nearly critical, biaxial, incommensurate charge density wave (CDW) correlations akin to those recently observed at higher doping levels, but with reduced amplitude and strong uniaxial anisotropy. The CDW amplitude and correlation length are enhanced as superconductivity is weakened by an external magnetic field. Analogous experiments were carried on YBa$_2$Cu$_3$O$_{6.6}$ crystals with a dilute concentration of spinless (Zn) impurities, which had earlier been shown to nucleate incommensurate magnetic order. Compared to pristine crystals with the same doping level, the CDW correlation length was found to be strongly reduced. These results indicate a three-phase competition between spin-modulated, charge-modulated, and superconducting states.
View original:
http://arxiv.org/abs/1212.5580
No comments:
Post a Comment