  In ferromagnetic oxide epitaxial multilayers, magnetic properties and
interlayer coupling are determined by a variety of factors. Beyond the
contribution of interlayer exchange coupling, strain and interfacial effects,
such as structural reconstructions or charge transfer, play significant roles,
resulting in complex magnetic behaviour. In this study the interlayer coupling
of ferromagnetic La0.7Sr0.3Mn0.95Ru0.05O3 (LSMRO) layers (8 nm thick) was
investigated, when separated by epitaxial spacers of paramagnetic metallic
LaNiO3 (LNO), in stacks exhibiting perpendicular magnetic anisotropy. By
varying the thickness of the spacer, it was found that the coupling between two
LSMRO layers changes from antiferromagnetic (with a 4 unit cell thick LNO
spacer) to ferromagnetic (with a 6 unit cells thick LNO spacer). For
multilayers comprising five LSMRO layers and a 4 unit cell thick LNO spacer,
the antiferromagnetic coupling was preserved. However, the effective magnetic
anisotropy changed, causing the magnetization to cant more towards the in-plane
direction. This behavior was corroborated by X-ray magnetic circular dichroism
(XMCD) investigations at the Mn and Ni L3-edges. The XMCD results indicated
that the 4 unit cells thick LNO spacer in the multilayer become magnetically
ordered, closely following the magnetization of adjacent LSMRO layers.
