Anisotropic lattice strain induced by the enhanced electronic hybridization in SrTiO3

Abstract

We introduce enhanced hybridization of Ti 3d-O 2p electronic states by applying an inhomogeneous electric field to a perovskite oxide, SrTiO3, which leads to lattice deformation through electrostriction and the converse flexoelectric effect. However, unlike most studies revealing lattice responses to dipolar polarization, the enhanced electronic hybridization introduced in SrTiO3 is not strong enough to compensate local repulsions and gives rise to the off-centered Ti displacement. This is consistent with the fact that SrTiO3 has a small vibronic coupling constant compared to other ferroelectric materials. In situ time-dependent X-ray diffraction studies reveal lattice relaxation. Band structures and electronic hybridization play important roles in lattice relaxation, which is different from the relaxation of metals where the carrier concentration may be dominant. Our results provide insight into the coupling behaviors between the lattice and electronic hybridization, considering both static and dynamic aspects.