We have observed a Fermi-surface (FS) induced lattice modulation in a YBCO superconductor with a wavevector along CuO chains, {\it i.e.} q1=(0,δ,0). The value of δ∼0.21 is twice the Fermi wavevector (2kF) along {\bf b*} connecting nearly nested FS `ridges'. The q1 modulation exists only within O-vacancy-ordered islands (characterized by q0=(41,0,0)) and persists well above and below Tc. Our results are consistent with the presence of a FS-induced charge-density wave.
@article{arxiv.0805.4193,
title = {Fermi-surface induced modulation in an optimally doped YBCO superconductor},
author = {Xuerong Liu and Zahirul Islam and Sunil K. Sinha and Simon C. Moss and Robert J. McQueeney and Jonathan C. Lang and Ulrich Welp},
journal= {arXiv preprint arXiv:0805.4193},
year = {2013}
}