Ferroelectricity and spin-orbit coupling in layered Aurivillius oxides

Key challenges in developing new materials platforms for spintronics include generating spin-polarized currents, maintaining spin polarization across nanoscale dimensions, and enabling external control. The relativistic spin-orbit interaction, along with certain crystalline symmetries, produces a unidirectional spin-orbit field that protects the spin-polarized carriers from decoherence due to momentum scattering processes, and is known as a persistent spin texture (PST). The polar Aurivillius oxides, (Bi2O2)(An-1BnO3n+1), are a family of layered perovskites that are promising for use as ferroelectric nonvolatile memories due to their high Curie temperatures, but have been less well studied as hosts for PSTs. The n=1 member of the Aurivillius series (Bi2WO6) is ferroelectric and exhibits large Rashba spin-splitting, motivating the study of alternative candidates in the Aurivillius family. Here, we study the effects of dimensionality (number of perovskite layers) and anion/cation chemistry on ferroelectricity and spin texture in the Aurivillius series.