Control of valency and structural properties of [111] oriented oxide interfaces*

Oxide thin films grown on [111] oriented substrates can give rise to new properties due to a different imposed crystal symmetry enforced by the growth direction. For example, a [111] oriented LaMnO₃ bilayer is predicted to host topological states [1,2], which arises due to the combination of a buckled honeycomb lattice and spin orbit coupling [3]. We experimentally investigated these system by fabricating LaMnO₃ bilayers and thin films on different substrates by means of pulsed laser deposition and characterize them by scanning transmission electron microscopy. We show that interface effects such as interdiffusion and the polar mismatch are important for the structural and electronic properties of bilayers in the [111] direction and can also give rise to unexpected oxygen distortions in thin films. Furthermore, the tunability of these properties by means of a buffer layer or strain is illustrated.

[1] Xiao, D et al., Nature Communications, 2, 1. (2011).

[2] Doennig, D et al., Physical Review B, 93, 16 (2016).

[3] Kane, C. L., & Mele, E. J. Physical Review Letters, 95, 22 (2005).