Anisotropic pinned/biased magnetization in SrRuO3/SrMnO3 superlattices

The exchange coupling at the interfaces of magnetic superlattices consisting of ferromagnetic SrRuO3 and antiferromagnetic SrMnO3 grown on ( 001) oriented SrTiO3 is studied with in-plane and out-of-plane orientations of the cooling magnetic field, with respect to the substrate plane. The magnetization of the in-plane, field cooled hysteresis loop is lower than the corresponding in-plane zero-field-cooled hysteresis loop. The out-of-plane field cooled hysteresis loop is shifted, from the origin, along the graphical magnetization axis. We attribute this irreversible rotation of the moment to the pinning/biasing of spin in the SrRuO3 layer in the vicinity of interfaces by the antiferromagnetic SrMnO3 layer.