Resonant tunneling across a ferroelectric domain wall

Motivated by recent experimental observations, we explore electron transport properties of a ferroelectric tunnel junction (FTJ) with an embedded head-to-head ferroelectric domain wall, using first-principles density-functional theory calculations. We consider a FTJ with $\mathrm{L}{\mathrm{a}}_{0.5}\mathrm{S}{\mathrm{r}}_{0.5}\mathrm{Mn}{\mathrm{O}}_{3}$ electrodes separated by a $\mathrm{BaTi}{\mathrm{O}}_{3}$ barrier layer and show that an in-plane charged domain wall in the ferroelectric $\mathrm{BaTi}{\mathrm{O}}_{3}$ can be induced by polar interfaces. The resulting $\mathsf{V}$-shaped electrostatic potential profile across the $\mathrm{BaTi}{\mathrm{O}}_{3}$ layer creates a quantum well and leads to the formation of a two-dimensional electron gas, which stabilizes the domain wall. The confined electronic states in the barrier are responsible for resonant tunneling as is evident from our quantum-transport calculations. We find that the resonant tunneling is an orbital selective process, which leads to sharp spikes in the momentum- and energy-resolved transmission spectra. Our results indicate that domain walls embedded in FTJs can be used to control the electron transport.