Direct observation of the quantum fluctuation controlled by ultraviolet irradiation inSrTiO3

Abstract
Temperature-dependent and photoinduced x-ray absorption spectra were measured in the Ti-K edge of SrTiO3. The change in the spectra is explained by a collapse of the inversion symmetry, accompanied by a relative local vibration of the Ti atom. In particular, photoinduced x-ray absorption measurements show that the single axial vibration of the Ti atom along the Ti-O direction was excited by UV irradiation only in the quantum paraelectric phase.