Complex structural-ferroelectric domain walls in thin films of hexagonal orthoferrites RFeO₃ (R = Lu, Er)

Hexagonal orthoferrites have recently attracted much attention as possible high-temperature ferromagnetic ferroelectrics. The ferroelectric domain structure of hexagonal RMnO₃, their antiferromagnetic structural analogies, has recently shown an atypical and complicated behavior. Hexagonal RFeO₃ are expected to exhibit similar domain structure that should coexist with weak ferromagnetic order and may represent a material with a unusual magnetoelectric interaction. In this report, we discuss microscopic ferroelectric domain structure of hexagonal orthoferrites in a thin-film state and demonstrate a distinct and unusual improper ferroelectric behavior of these oxide materials.