Anomalies in the TA-Phonon Branches of SrTiO3 in the Quantum Paraelectric Regime

Brillouin and neutron-scattering measurements of TA-phonon branches are reported for SrTiO3 at small wave vectors and at temperatures well below the 105 K structural transition. Anomalous softening in the former measurements, and dispersion in the latter, are found in the quantum paraelectric regime. Furthermore, an unexpected loss of scattered intensity is observed on the TA[100]-phonon branch at temperatures centred around 30 to 40 K.