${\left(\mathrm{LaCo}{\mathrm{O}}_3/\mathrm{LaMn}{\mathrm{O}}_3\right)}_5$ multilayers with fixed $\mathrm{LaMn}{\mathrm{O}}_3$ thickness and varying $\mathrm{LaCo}{\mathrm{O}}_3$ thickness grown on $\mathrm{SrTi}{\mathrm{O}}_3$ (001) substrates are studied by scanning transmission electron microscopy at the atomic scale. Utilizing peak pairs analysis on annular bright field images, the precise atomic positions and the degree of octahedral rotation are obtained. Our study shows that the $c$ axis of $\mathrm{LaMn}{\mathrm{O}}_3$ sandwiched by $\mathrm{LaCo}{\mathrm{O}}_3$ layers experiences a transition from the in-plane direction to the out-of-plane direction as the $\mathrm{LaCo}{\mathrm{O}}_3$ layer thickness increases, due to the oxygen octahedral coupling with $\mathrm{LaCo}{\mathrm{O}}_3$ layers. An abnormal suppression in saturation magnetization with increasing the thickness of the $\mathrm{LaCo}{\mathrm{O}}_3$ is observed and ascribed to the enhanced $\mathrm{Mn}{\mathrm{O}}_6$ octahedral rotation. Our work provides a way to tune the magnetic properties of epitaxially grown thin films via interfacial octahedral engineering.

• Received 2 February 2019
• Revised 24 May 2019

DOI:https://doi.org/10.1103/PhysRevB.100.014427