First-principles study of topologically protected vortices and ferroelectric domain walls in hexagonal YGaO3

Abstract

Ferroelectric behavior on the meso- and macroscopic scale depends on the formation and dynamics of domains and controlling the domain patterns is imperative to device performance. While density functional theory (DFT) calculations have successfully described the basic properties of ferroelectric domain walls, the necessarily small cell sizes used for the calculations hampers DFT studies of complex domain patterns. Here, we simulate large-scale complex ferroelectric domain patterns in ferroelectric YGaO3 using multisite local orbitals as implemented in the DFT code conquest. The multisite local orbital basis set gives similar bulk structural and electronic properties, and atomic domain wall structures and energetics as those obtained with conventional plane-wave DFT. With this basis set model, 3600-atom cells are used to simulate topologically protected vortices. The local atomic structure at the vortex cores is subtly different from the domain walls, with a lower electronic band gap suggesting enhanced local conductance at these cores.