Competing interactions at the interface between ferromagnetic oxides revealed by spin-polarized neutron reflectometry

Abstract

We have investigated the magnetization profiles in superlattices composed of the two ferromagnets La${}_{0.7}$Sr${}_{0.3}$MnO${}_{3}$ and SrRuO${}_{3}$ using spin-polarized neutron reflectometry. In combination with magnetometry, the neutron data indicate a noncollinear spin configuration where orientation of the Ru moments changes from in plane at the interface to out of plane deep inside the SrRuO${}_{3}$ layers. The spin structure originates in a competition between antiferromagnetic exchange interactions of Mn and Ru moments across the interface, and the magnetocrystalline anisotropy of the Ru moments, and it is closely related to the ``exchange spring'' structures previously observed in multilayers composed of ferromagnetic elements and alloys.