Total energy calculations for magnetic La$_{2/3}$S$_{1/3}$rMnO$_{3}$/SrRuO$_{3}$ bilayers

. Recently positive exchange bias was reported for ferromagnetic La$_{2/3}$Sr$_{1/3}$MnO$_{3}$/SrRuO$_{3}$ (LSMO/SRO) bilayers which indicated anti-ferromagnetic exchange interaction across the interface [1]. To address the physical origin of this anti-ferromagnetic exchange interaction, we have performed first principles calculations with both ferro, and anti-ferromagnetic interface structures. We have found that the anti-ferromagnetic interface is preferred to ferromagnetic case energetically. The calculations indicate the interfacial O 2p orbitals and their interaction with Mn, Ru spin polarized 3d orbitals are critical for this anti-ferromagnetic interface preference. In this talk, we will discuss the total energy calculations with various magnetic structures near the interface. [1] X. Ke \textit{et al}. Appl. Phys. Lett. \textbf{84}, 5458 (2004)