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Strain engineering with different substrate facets is promising for tuning functional properties of thin film perovskite oxides. By choice of facet, different surface symmetries and chemical bond directions for epitaxial interfaces can be tailored. Here, preparation of well-defined pseudo-cubic (111)-oriented orthorhombic substrates of DyScO3 , GdScO3 , and NdGaO3 is reported. The choice of orthorhombic facet, (011)o or (101)o , both corresponding to pseudo-cubic (111)pc , gives vicinal surfaces with single or double (111pc layer terrace step heights, respectively, impacting subsequent thin film growth. Orthorhombic LaFeO3 epitaxy on the (101)o facet reveals a distinction between alternating (111)pc layers, both during and after growth. The observed differences are explained based on the oxygen octahedral tilt pattern relative to the two orthorhombic (111)pc surfaces. This robust structural detail in the orthorhombic perovskite oxides enables utilisation of different (111)pc facets for property engineering, through polyhedral connectivity control and cation coordination at epitaxial interfaces.

© 2018 IOP Publishing Ltd. Using strain, i.e. subtle changes in lattice constant in a thin film induced by the underlying substrate, opens up intriguing new ways to control material properties. We present a study of the effects of strain on structural and ferromagnetic properties of (1 1 1)pc-oriented La0.7Sr0.3MnO3epitaxial thin films grown on NdGaO3, SrTiO3, and DyScO3substrates. (The subscript pc denotes the pseudo-cubic symmetry.) The results show that La0.7Sr0.3MnO3assumes a monoclinic unit cell on NdGaO3and DyScO3and a rhombohedral unit cell on SrTiO3. For La0.7Sr0.3MnO3on NdGaO3and DyScO3a uniaxial magnetic anisotropy is found, while La0.7Sr0.3MnO3on SrTiO3is magnetically isotropic. The Néel model is used to explain the anisotropy of the thin films on NdGaO3and SrTiO3, however, for La0.7Sr0.3MnO3on DyScO3the effect of octahedral rotations needs to be included through the single ion model. Through examination of the Curie temperature of the strained films we suggest that (1 1 1)-strain has a different effect on the Jahn-Teller splitting of egand t2gelectron levels than what is seen in (0 0 1)pc-oriented La0.7Sr0.3MnO3thin films.

We observe an induced switchable magnetic moment of 1.6±0.40μB/Fe for the nominally antiferromagnetic LaFeO3 extending two to four interface layers into the non-charge transfer system La0.7Sr0.3MnO3/LaFeO3/SrTiO3(111). Simultaneously a mismatch of oxygen octahedra rotations at the interface implies an atomic reconstruction of reduced symmetry at the interface, reaching two to five layers into LaFeO3. Density functional theory of a structure with atomic reconstruction and different correlation strength shows a ferrimagnetic state with a net Fe moment at the interface. Together these results suggest that engineered oxygen octahedra rotations, affecting the local symmetry, affect electron correlations and can be used to promote magnetic properties.