Phonon anomaly of under-doped YBa2Cu3O6.6 studied by neutron scattering

Total Pair Correlation Function (T(r)). and phonon density of states (PDOS) were measured by neutron scattering on the powder sample of YBa2Cu3O6.6 (T-c similar to 60 K) at temperatures between 20 and 295 K. Lattice anomalies were observed in the T(r) and PDOS much above T-c as well as T-c. These results indicate that the anomaly at T-c can be related to the superconducting transition but one above T-c may be attributed to the induced lattice anomaly caused by the pseudo-spin-gap opening.