Effect of Polarization on the Band Structure at a Charged Domain Wall in Ferroelectric Materials

The interplay between electron charge, spin, and ferroelectric polarization is under-explored for conducting ferroelectric domain walls (DWs). DWs are interfaces that separate regions (domains) within a material that have different orientations of spontaneous polarization. We investigated the electronic band structure of t2g electrons, confined to 90° charged do main walls (CDWs) in barium titanate (BaTiO3), a prototypical perovskite ferroelectric. A key novel aspect of our study is the explicit inclusion of both orbital and spin degrees of freedom in the Hamiltonian. This leads to an Ising-type spin-orbit coupling (SOC). We constructed a tight-binding (TB) model for t2g electrons that is constrained by symmetries of the DW, including time-reversal, mirror, and rotational symmetries. First-principles density functional theory (DFT) calculations were performed to extract the TB parame ters. Our findings offer new insights into spin-orbit interactions at ferroelectric domain walls and open avenues for their potential use in next-generation electronic and spintronic devices