Incommensurate One-Dimensional Fluctuations inYBa2Cu3O6.93

A novel neutron scattering technique has been utilized to discover one-dimensional fluctuations with a very sharply defined modulation period of $16.65Å$ along the $\mathbf{b}\left(\mathbf{a}\right)$ direction in ${\mathrm{YBa}}_2{\mathrm{Cu}}_3{\mathrm{O}}_{6.93}$. The fluctuations are found to be absent in the reduced oxygen compound ${\mathrm{YBa}}_2{\mathrm{Cu}}_3{\mathrm{O}}_{6.15}$. The wave vector of the fluctuations is consistent with accepted values of ${2k}_F$ for the Cu-O chains.