Evolution of magnetic phases and orbital occupation in (SrMnO3)n/(LaMnO3)2n superlattices

The magnetic and electronic modifications induced at the interfaces in (SrMnO${}_3$)${}_n$/(LaMnO${}_3$)${}_{2n}$ superlattices have been investigated by linear and circular magnetic dichroism in the Mn L${}_{2,3}$ x-ray absorption spectra. Together with theoretical calculations, our data demonstrate that the charge redistribution across interfaces favors in-plane ferromagnetic (FM) order and $e_g(x^2-y^2)$ orbital occupation, in agreement with the average strain. Far from interfaces, inside LaMnO${}_3$, electron localization and local strain favor antiferromagnetism (AFM) and $e_g(3z^2-r^2)$ orbital occupation. For $n=1$ the high density of interfacial planes ultimately leads to dominant FM order forcing the residual AFM phase to be in-plane too, while for $n\ge 5$ the FM layers are separated by AFM regions having out-of-plane spin orientation.