  Manipulation of octahedral distortion at atomic length scale is an effective
means to tune the physical ground states of functional oxides. Previous work
demonstrates that epitaxial strain and film thickness are variable parameters
to modify the octahedral rotation and tilt. However, selective control of
bonding geometry by structural propagation from adjacent layers is rarely
studied. Here we propose a new route to tune the ferromagnetic response in
SrRuO3 (SRO) ultrathin layers by oxygen coordination of adjacent SrCuO2 (SCO)
layers. The infinite-layered CuO2 in SCO exhibits a structural transformation
from "planar-type" to "chain-type" as reducing film thickness. These two
orientations dramatically modify the polyhedral connectivity at the interface,
thus altering the octahedral distortion of SRO. The local structural variation
changes the spin state of Ru and hybridization strength between Ru 4d and O 2p
orbitals, leading to a significant change in the magnetoresistance and
anomalous Hall resistivity of SRO layers. These findings could launch further
investigations into adaptive control of magnetoelectric properties in quantum
oxide heterostructures using oxygen coordination.
