X-ray absorption study of the local dipole moment in SrTiO3 under uniaxial pressure

X-ray absorption spectra under uniaxial pressure were measured at the Ti K -edge of a SrTiO 3 single crystal in order to obtain direct evidence for the ferroelectric transition that is expected on the basis of second harmonic generation studies. A uniaxial pressure was applied perpendicular to the ab -plane. The pre-edge peak, which corresponds to Ti 3 d e g -O 2 pσ bonding, shows little change across the transition temperature of 40 K at 1 GPa. This indicates that a local electric dipole moment is not induced under uniaxial pressure, as opposed to the macroscopic ferroelectric moments that are predicted to be induced along the ab -plane.