Mechanism of intrinsic dipole moment induction in quantum paraelectric SrTiO3

Abstract

We measure the Ti Kβ resonant X-ray emission spectra of SrTiO3 in the quantum paraelectric phase. We find that charge transfer (CT) excitation is affected by temperature decrease and UV irradiation, which provides direct evidence of the fact that the induced electric dipole moment is derived from the Ti off-center displacement. The UV-assisted dipole moments are aligned parallel to the applied DC electric field, as inferred from the additional change in the CT peak. We conclude that the local polar region formed by UV irradiation evolves under DC field application at low temperature.