  Extraordinary electronic phases can form in artificial oxide
heterostructures, which will provide a fertile ground for new physics and also
give rise to novel device functions. Based on a systematic first-principles
density functional theory study of the magnetic and electronic properties of
the (111) superlattices (ABO3)2/(AB'O3)10 of 4d and 5d transition metal
perovskite (B = Ru, Rh, Ag, Re, Os, Ir, Au; AB'O3 = LaAlO3, SrTiO3), we
demonstrate that due to quantum confinement, bilayers (LaBO3)2 (B = Ru, Re, Os)
and (SrBO3)2 (B = Rh, Os, Ir) are ferromagnetic with ordering temperatures up
to room temperature. In particular, bilayer (LaOsO3)2 is an exotic
spin-polarized quantum anomalous Hall insulator, while the other ferromagnetic
bilayers are metallic with large Hall conductances comparable to the
conductance quantum. Furthermore, bilayers (LaRuO3)2 and (SrRhO3)2 are
half-metallic, while bilayer (SrIrO3)2 exhibits peculiar colossal magnetic
anisotropy. Our findings thus show that 4d and 5d metal perovskite (111)
bilayers are a class of quasi-two-dimensional materials for exploring exotic
quantum phases and also for advanced applications such as low-power
nanoelectronics and oxide spintronics.
